Distant Horizons shader support (#1553)

dependencies.gradle

@@ -136,6 +136,9 @@ dependencies {
     // Better Crashes
     compileOnly("com.github.GTNewHorizons:BetterCrashes:1.4.1-GTNH:dev")
 
+    // Distant Horizons
+    compileOnly("maven.modrinth:DistantHorizonsApi:5.1.0")
+
     afterEvaluate {
         dependencies {
             testImplementation(platform('org.junit:junit-bom:5.14.1'))

src/main/java/com/gtnewhorizons/angelica/iris/IrisGLSMBridge.java

@@ -14,6 +14,7 @@ import net.coderbot.iris.pipeline.DeferredWorldRenderingPipeline;
 import net.coderbot.iris.pipeline.WorldRenderingPipeline;
 import net.coderbot.iris.samplers.IrisSamplers;
 import net.coderbot.iris.texture.pbr.PBRTextureManager;
+import net.coderbot.iris.vertices.ImmediateState;
 
 public class IrisGLSMBridge {
 
@@ -114,7 +115,7 @@ public class IrisGLSMBridge {
             if (!drp.shouldOverrideShaders()) return;
             if (drp.getActivePassProgramId() == -1) return;
 
-            if (DepthColorStorage.isOwnedProgram(event.newProgram)) {
+            if (!ImmediateState.isRenderingLevel || DepthColorStorage.isOwnedProgram(event.newProgram)) {
                 DepthColorStorage.unlockDepthColor();
             } else {
                 drp.onModProgramOverride();

src/main/java/net/coderbot/iris/Iris.java

@@ -7,6 +7,7 @@ import com.gtnewhorizons.angelica.AngelicaMod;
 import com.gtnewhorizons.angelica.Tags;
 import com.gtnewhorizons.angelica.config.AngelicaConfig;
 import cpw.mods.fml.client.registry.ClientRegistry;
+import cpw.mods.fml.common.Loader;
 import cpw.mods.fml.common.eventhandler.SubscribeEvent;
 import cpw.mods.fml.common.gameevent.InputEvent;
 import it.unimi.dsi.fastutil.ints.Int2IntMap;
@@ -17,6 +18,7 @@ import net.coderbot.iris.block_rendering.BlockRenderingSettings;
 import com.gtnewhorizons.angelica.config.AngelicaConfig;
 import net.coderbot.iris.celeritas.IrisCeleritasShaderProvider;
 import com.gtnewhorizons.angelica.rendering.celeritas.api.IrisShaderProviderHolder;
+import net.coderbot.iris.compat.dh.DHCompat;
 import net.coderbot.iris.config.IrisConfig;
 import net.coderbot.iris.gl.shader.StandardMacros;
 import net.coderbot.iris.gui.screen.ShaderPackScreen;
@@ -113,11 +115,31 @@ public class Iris {
     // Used in favor of queueDefaultShaderPackOptionValues() for resetting as the
     // behavior is more concrete and therefore is more likely to repair a user's issues
     private static boolean resetShaderPackOptions = false;
+    private static boolean loadShaderPackWhenPossible = false;
 
     private static String IRIS_VERSION;
     @Getter
     private static boolean fallback;
 
+    public static boolean loadedIncompatiblePack() {
+        return DHCompat.lastPackIncompatible();
+    }
+
+    public static void loadShaderpackWhenPossible() {
+        loadShaderPackWhenPossible = true;
+    }
+
+    public static void tryLoadShaderpackWhenPossible() {
+        if (loadShaderPackWhenPossible) {
+            loadShaderPackWhenPossible = false;
+            try {
+                reload();
+            } catch (IOException e) {
+                logger.error("Error during deferred shader reload", e);
+            }
+        }
+    }
+
     /**
      * Lazy executor for parallelizing shader transformations during shader pack loading.
      * Creates threads on demand and shuts down after a period of inactivity.
@@ -350,6 +372,7 @@ public class Iris {
      * <p>This is called right before options are loaded, so we can add key bindings here.</p>
      */
     public void onEarlyInitialize() {
+        DHCompat.run();
         try {
             if (!Files.exists(getShaderpacksDirectory())) {
                 Files.createDirectories(getShaderpacksDirectory());
@@ -395,8 +418,19 @@ public class Iris {
 
         PBRTextureManager.INSTANCE.init();
 
-        // Only load the shader pack when we can access OpenGL
-        loadShaderpack();
+        boolean isDHLoaded;
+        try {
+            Class.forName("com.seibel.distanthorizons.DistantHorizonsTweaker");
+            isDHLoaded = true;
+        }
+        catch (Exception e) {
+            isDHLoaded = false;
+        }
+
+        // When DH is present, defer shaderpack loading until its init callback has run.
+        if (!isDHLoaded) {
+            loadShaderpack();
+        }
     }
 
     /**
@@ -721,6 +755,12 @@ public class Iris {
 
             BlockRenderingSettings.INSTANCE.reloadRendererIfRequired();
         }
+
+        if (loadedIncompatiblePack() && Minecraft.getMinecraft().thePlayer != null) {
+            Iris.logger.warn("Incompatible pack for DH!");
+            Minecraft.getMinecraft().thePlayer.addChatMessage(new ChatComponentText(EnumChatFormatting.BOLD.toString() + EnumChatFormatting.RED + "This pack doesn't have DH support."));
+            Minecraft.getMinecraft().thePlayer.addChatMessage(new ChatComponentText(EnumChatFormatting.RED + "Distant Horizons (DH) chunks won't show up. This isn't a bug, get another shader."));
+        }
     }
 
     /**

src/main/java/net/coderbot/iris/compat/dh/DHCompat.java

@@ -1,14 +1,129 @@
 package net.coderbot.iris.compat.dh;
 
-/**
- * Stub implementation of Distant Horizons compatibility.
- */
-public class DHCompat {
-	public int getDepthTex() {
-		return 0;
-	}
+import com.gtnewhorizons.angelica.rendering.RenderingState;
+import net.coderbot.iris.Iris;
+import net.coderbot.iris.pipeline.DeferredWorldRenderingPipeline;
+import net.minecraft.client.Minecraft;
+import org.joml.Matrix4f;
+import org.joml.Matrix4fc;
 
-	public int getDepthTexNoTranslucent() {
-		return 0;
-	}
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+import java.lang.reflect.InvocationTargetException;
+
+public class DHCompat {
+    private static boolean dhPresent;
+    private static boolean lastIncompatible;
+    private DHCompatInternal compatInternalInstance;
+    private final static Matrix4f tempProj = new Matrix4f();
+
+    public DHCompat(DeferredWorldRenderingPipeline pipeline, boolean renderDHShadow) {
+        if (pipeline == null) {
+            return;
+        }
+        try {
+            if (dhPresent) {
+                compatInternalInstance = new DHCompatInternal(pipeline, renderDHShadow);
+                lastIncompatible = compatInternalInstance.incompatiblePack();
+            }
+        } catch (Throwable e) {
+            lastIncompatible = false;
+            if (e instanceof InvocationTargetException ite) {
+                throw new RuntimeException("Unknown error loading Distant Horizons compatibility.", ite.getCause());
+            } else {
+                throw new RuntimeException("Unknown error loading Distant Horizons compatibility.", e);
+            }
+        }
+
+    }
+
+    public static Matrix4fc getProjection() {
+        Matrix4f projection = RenderingState.INSTANCE.getProjectionMatrix();
+        if (!dhPresent) {
+            return projection;
+        }
+
+        return tempProj.setPerspective(projection.perspectiveFov(), projection.m11() / projection.m00(), DHCompat.getNearPlane(), DHCompat.getFarPlane());
+    }
+
+    public static void run() {
+        try {
+            Class.forName("com.seibel.distanthorizons.DistantHorizonsTweaker");
+            dhPresent = true;
+        }
+        catch (Exception e) {
+            dhPresent = false;
+        }
+        try {
+            if (dhPresent) {
+                LodRendererEvents.setupEventHandlers();
+            }
+        } catch (Throwable e) {
+            dhPresent = false;
+            if (e instanceof ExceptionInInitializerError eiie) {
+                throw new RuntimeException("Failure loading DH compat.", eiie.getCause());
+            } else {
+                throw new RuntimeException("DH found, but one or more API methods are missing. Iris requires DH [2.0.4] or DH API version [1.1.0] or newer. Please make sure you are on the latest version of DH and Iris.", e);
+            }
+        }
+    }
+
+    public static boolean lastPackIncompatible() {
+        return dhPresent && hasRenderingEnabled() && lastIncompatible;
+    }
+
+    public static float getFarPlane() {
+        if (!dhPresent) return 0.01f;
+        return DHCompatInternal.getFarPlane();
+    }
+
+    public static float getNearPlane() {
+        if (!dhPresent) return 0.01f;
+        return DHCompatInternal.getNearPlane();
+    }
+
+    public static int getRenderDistance() {
+        if (!dhPresent) return Minecraft.getMinecraft().gameSettings.renderDistanceChunks * 16;
+
+        return DHCompatInternal.getRenderDistance();
+    }
+
+    public static boolean checkFrame() {
+        if (!dhPresent) {
+            return false;
+        }
+
+        return DHCompatInternal.checkFrame();
+    }
+
+    public static boolean hasRenderingEnabled() {
+        if (!dhPresent) {
+            return false;
+        }
+
+        return checkFrame();
+    }
+
+    public void clearPipeline() {
+        if (compatInternalInstance == null) return;
+
+        compatInternalInstance.clear();
+    }
+
+    public int getDepthTex() {
+        if (compatInternalInstance == null) return -1;
+
+        return compatInternalInstance.getStoredDepthTex();
+    }
+
+    public int getDepthTexNoTranslucent() {
+        if (compatInternalInstance == null) return -1;
+
+        return compatInternalInstance.getDepthTexNoTranslucent();
+    }
+
+    public DHCompatInternal getInstance() {
+        return compatInternalInstance;
+    }
 }

src/main/java/net/coderbot/iris/compat/dh/DHCompatInternal.java

@@ -0,0 +1,291 @@
+package net.coderbot.iris.compat.dh;
+
+import com.gtnewhorizons.angelica.glsm.GLStateManager;
+import com.seibel.distanthorizons.api.DhApi;
+import com.seibel.distanthorizons.api.interfaces.override.rendering.IDhApiFramebuffer;
+import com.seibel.distanthorizons.api.interfaces.override.rendering.IDhApiGenericObjectShaderProgram;
+import com.seibel.distanthorizons.api.objects.math.DhApiVec3f;
+import com.seibel.distanthorizons.coreapi.DependencyInjection.OverrideInjector;
+import net.coderbot.iris.Iris;
+import net.coderbot.iris.gl.framebuffer.GlFramebuffer;
+import net.coderbot.iris.gl.texture.DepthBufferFormat;
+import net.coderbot.iris.gl.texture.DepthCopyStrategy;
+import net.coderbot.iris.pipeline.DeferredWorldRenderingPipeline;
+import net.coderbot.iris.rendertarget.DepthTexture;
+import net.coderbot.iris.rendertarget.IRenderTargetExt;
+import net.coderbot.iris.shaderpack.CloudSetting;
+import net.coderbot.iris.shaderpack.ProgramSource;
+import net.coderbot.iris.uniforms.CapturedRenderingState;
+import net.irisshaders.iris.api.v0.IrisApi;
+import net.minecraft.client.Minecraft;
+import org.lwjgl.opengl.GL11;
+
+import java.io.IOException;
+
+public class DHCompatInternal {
+    public static final DHCompatInternal SHADERLESS = new DHCompatInternal(null, false);
+    static boolean dhEnabled;
+    private static int guiScale = -1;
+    private final DeferredWorldRenderingPipeline pipeline;
+    public boolean shouldOverrideShadow;
+    public boolean shouldOverride;
+    private GlFramebuffer dhGenericFramebuffer;
+    private IrisLodRenderProgram solidProgram;
+    private IrisGenericRenderProgram genericShader;
+    private IrisLodRenderProgram translucentProgram;
+    private IrisLodRenderProgram shadowProgram;
+    private GlFramebuffer dhTerrainFramebuffer;
+    private DhFrameBufferWrapper dhTerrainFramebufferWrapper;
+    private GlFramebuffer dhWaterFramebuffer;
+    private GlFramebuffer dhShadowFramebuffer;
+    private DhFrameBufferWrapper dhShadowFramebufferWrapper;
+    private DepthTexture depthTexNoTranslucent;
+    private boolean translucentDepthDirty;
+    private int storedDepthTex = -1;
+    private boolean incompatible = false;
+    private int cachedVersion;
+
+    public DHCompatInternal(DeferredWorldRenderingPipeline pipeline, boolean dhShadowEnabled) {
+        this.pipeline = pipeline;
+
+        if (pipeline == null || !DhApi.Delayed.configs.graphics().renderingEnabled().getValue()) {
+            return;
+        }
+
+        if (pipeline.getDHTerrainShader().isEmpty() && pipeline.getDHWaterShader().isEmpty()) {
+            Iris.logger.warn("No DH shader found in this pack.");
+            incompatible = true;
+            return;
+        }
+
+        cachedVersion = ((IRenderTargetExt) Minecraft.getMinecraft().getFramebuffer()).iris$getDepthBufferVersion();
+
+        createDepthTex(Minecraft.getMinecraft().getFramebuffer().framebufferWidth, Minecraft.getMinecraft().getFramebuffer().framebufferHeight);
+        translucentDepthDirty = true;
+
+        ProgramSource terrain = pipeline.getDHTerrainShader().get();
+        solidProgram = IrisLodRenderProgram.createProgram(terrain.getName(), false, false, terrain, pipeline.getCustomUniforms(), pipeline);
+
+        ProgramSource generic = pipeline.getDHGenericShader().get();
+        genericShader = IrisGenericRenderProgram.createProgram(generic.getName() + "_g", false, false, generic, pipeline.getCustomUniforms(), pipeline);
+        dhGenericFramebuffer = pipeline.createDHFramebuffer(generic, false);
+
+        if (pipeline.getDHWaterShader().isPresent()) {
+            ProgramSource water = pipeline.getDHWaterShader().get();
+            translucentProgram = IrisLodRenderProgram.createProgram(water.getName(), false, true, water, pipeline.getCustomUniforms(), pipeline);
+            dhWaterFramebuffer = pipeline.createDHFramebuffer(water, true);
+        }
+
+        if (pipeline.getDHShadowShader().isPresent() && dhShadowEnabled) {
+            ProgramSource shadow = pipeline.getDHShadowShader().get();
+            shadowProgram = IrisLodRenderProgram.createProgram(shadow.getName(), true, false, shadow, pipeline.getCustomUniforms(), pipeline);
+            if (pipeline.hasShadowRenderTargets()) {
+                dhShadowFramebuffer = pipeline.createDHFramebufferShadow(shadow);
+                dhShadowFramebufferWrapper = new DhFrameBufferWrapper(dhShadowFramebuffer);
+            }
+            shouldOverrideShadow = true;
+        } else {
+            shouldOverrideShadow = false;
+        }
+
+        dhTerrainFramebuffer = pipeline.createDHFramebuffer(terrain, false);
+        dhTerrainFramebufferWrapper = new DhFrameBufferWrapper(dhTerrainFramebuffer);
+
+        if (translucentProgram == null) {
+            translucentProgram = solidProgram;
+        }
+
+        shouldOverride = true;
+    }
+
+    public static int getDhBlockRenderDistance() {
+        if (DhApi.Delayed.configs == null || !dhEnabled) {
+            // Called before DH has finished setup
+            return Minecraft.getMinecraft().gameSettings.renderDistanceChunks * 16;
+        }
+
+        return DhApi.Delayed.configs.graphics().chunkRenderDistance().getValue() * 16;
+    }
+
+    public static int getRenderDistance() {
+        return getDhBlockRenderDistance();
+    }
+
+    public static float getFarPlane() {
+        if (DhApi.Delayed.configs == null) {
+            // Called before DH has finished setup
+            return 0;
+        }
+
+        int lodChunkDist = DhApi.Delayed.configs.graphics().chunkRenderDistance().getValue();
+        int lodBlockDist = lodChunkDist * 16;
+        // sqrt 2 to prevent the corners from being cut off
+        return (float) ((lodBlockDist + 512) * Math.sqrt(2));
+    }
+
+    public static float getNearPlane() {
+        if (DhApi.Delayed.renderProxy == null) {
+            // Called before DH has finished setup
+            return 0;
+        }
+
+        return DhApi.Delayed.renderProxy.getNearClipPlaneDistanceInBlocks(CapturedRenderingState.INSTANCE.getTickDelta());
+    }
+
+    public static boolean checkFrame() {
+        if (guiScale == -1) {
+            guiScale = Minecraft.getMinecraft().gameSettings.guiScale;
+        }
+
+        if (DhApi.Delayed.configs == null) return dhEnabled;
+
+        if ((dhEnabled != DhApi.Delayed.configs.graphics().renderingEnabled().getValue() || guiScale != Minecraft.getMinecraft().gameSettings.guiScale)
+            && IrisApi.getInstance().isShaderPackInUse()) {
+            guiScale = Minecraft.getMinecraft().gameSettings.guiScale;
+            dhEnabled = DhApi.Delayed.configs.graphics().renderingEnabled().getValue();
+            try {
+                Iris.reload();
+            } catch (IOException e) {
+                throw new RuntimeException(e);
+            }
+        }
+
+        return dhEnabled;
+    }
+
+    public boolean incompatiblePack() {
+        return incompatible;
+    }
+
+    public void reconnectDHTextures(int depthTex) {
+        if (((IRenderTargetExt) Minecraft.getMinecraft().getFramebuffer()).iris$getDepthBufferVersion() != cachedVersion) {
+            cachedVersion = ((IRenderTargetExt) Minecraft.getMinecraft().getFramebuffer()).iris$getDepthBufferVersion();
+            createDepthTex(Minecraft.getMinecraft().getFramebuffer().framebufferWidth, Minecraft.getMinecraft().getFramebuffer().framebufferHeight);
+        }
+        if (storedDepthTex != depthTex && dhTerrainFramebuffer != null) {
+            storedDepthTex = depthTex;
+            dhTerrainFramebuffer.addDepthAttachmentBypass(depthTex);
+            if (dhWaterFramebuffer != null) {
+                dhWaterFramebuffer.addDepthAttachmentBypass(depthTex);
+            }
+            if (dhGenericFramebuffer != null) {
+                dhGenericFramebuffer.addDepthAttachmentBypass(depthTex);
+            }
+        }
+    }
+
+    public void createDepthTex(int width, int height) {
+        if (depthTexNoTranslucent != null) {
+            depthTexNoTranslucent.destroy();
+            depthTexNoTranslucent = null;
+        }
+
+        translucentDepthDirty = true;
+
+        depthTexNoTranslucent = new DepthTexture(width, height, DepthBufferFormat.DEPTH32F);
+    }
+
+    public void clear() {
+        if (solidProgram != null) {
+            solidProgram.free();
+            solidProgram = null;
+        }
+        if (translucentProgram != null) {
+            translucentProgram.free();
+            translucentProgram = null;
+        }
+        if (shadowProgram != null) {
+            shadowProgram.free();
+            shadowProgram = null;
+        }
+        shouldOverrideShadow = false;
+        shouldOverride = false;
+        dhTerrainFramebuffer = null;
+        dhWaterFramebuffer = null;
+        dhShadowFramebuffer = null;
+        storedDepthTex = -1;
+        translucentDepthDirty = true;
+
+        OverrideInjector.INSTANCE.unbind(IDhApiFramebuffer.class, dhTerrainFramebufferWrapper);
+        OverrideInjector.INSTANCE.unbind(IDhApiGenericObjectShaderProgram.class, genericShader);
+        OverrideInjector.INSTANCE.unbind(IDhApiFramebuffer.class, dhShadowFramebufferWrapper);
+        dhTerrainFramebufferWrapper = null;
+        dhShadowFramebufferWrapper = null;
+    }
+
+    public void setModelPos(DhApiVec3f modelPos) {
+        solidProgram.bind();
+        solidProgram.setModelPos(modelPos);
+        translucentProgram.bind();
+        translucentProgram.setModelPos(modelPos);
+        solidProgram.bind();
+    }
+
+    public IrisLodRenderProgram getSolidShader() {
+        return solidProgram;
+    }
+
+    public GlFramebuffer getSolidFB() {
+        return dhTerrainFramebuffer;
+    }
+
+    public DhFrameBufferWrapper getSolidFBWrapper() {
+        return dhTerrainFramebufferWrapper;
+    }
+
+    public IrisLodRenderProgram getShadowShader() {
+        return shadowProgram;
+    }
+
+    public GlFramebuffer getShadowFB() {
+        return dhShadowFramebuffer;
+    }
+
+    public DhFrameBufferWrapper getShadowFBWrapper() {
+        return dhShadowFramebufferWrapper;
+    }
+
+    public IrisLodRenderProgram getTranslucentShader() {
+        if (translucentProgram == null) {
+            return solidProgram;
+        }
+        return translucentProgram;
+    }
+
+    public int getStoredDepthTex() {
+        return storedDepthTex;
+    }
+
+    public void copyTranslucents(int width, int height) {
+        if (translucentDepthDirty) {
+            translucentDepthDirty = false;
+            GLStateManager.glBindTexture(GL11.GL_TEXTURE_2D, depthTexNoTranslucent.getTextureId());
+            dhTerrainFramebuffer.bindAsReadBuffer();
+            GLStateManager.glCopyTexImage2D(GL11.GL_TEXTURE_2D, 0, DepthBufferFormat.DEPTH32F.getGlInternalFormat(), 0, 0, width, height, 0);
+        } else {
+            DepthCopyStrategy.fastest(false).copy(dhTerrainFramebuffer, storedDepthTex, null, depthTexNoTranslucent.getTextureId(), width, height);
+        }
+    }
+
+    public GlFramebuffer getTranslucentFB() {
+        return dhWaterFramebuffer;
+    }
+
+    public GlFramebuffer getGenericFB() {
+        return dhGenericFramebuffer;
+    }
+
+    public int getDepthTexNoTranslucent() {
+        if (depthTexNoTranslucent == null) return 0;
+
+        return depthTexNoTranslucent.getTextureId();
+    }
+
+    public IDhApiGenericObjectShaderProgram getGenericShader() {
+        return genericShader;
+    }
+
+    public boolean avoidRenderingClouds() {
+        return pipeline != null && (pipeline.getDHCloudSetting() == CloudSetting.OFF || (pipeline.getDHCloudSetting() == CloudSetting.DEFAULT && pipeline.getCloudSetting() == CloudSetting.OFF));
+    }
+}

src/main/java/net/coderbot/iris/compat/dh/DhFrameBufferWrapper.java

@@ -0,0 +1,55 @@
+package net.coderbot.iris.compat.dh;
+
+import com.gtnewhorizons.angelica.glsm.GLStateManager;
+import com.seibel.distanthorizons.api.interfaces.override.rendering.IDhApiFramebuffer;
+import net.coderbot.iris.gl.framebuffer.GlFramebuffer;
+import org.lwjgl.opengl.GL30;
+
+public class DhFrameBufferWrapper implements IDhApiFramebuffer {
+    private final GlFramebuffer framebuffer;
+
+
+    public DhFrameBufferWrapper(GlFramebuffer framebuffer) {
+        this.framebuffer = framebuffer;
+    }
+
+
+    @Override
+    public boolean overrideThisFrame() {
+        return true;
+    }
+
+    @Override
+    public void bind() {
+        this.framebuffer.bind();
+    }
+
+    @Override
+    public void addDepthAttachment(int i, boolean b) {
+        // ignore
+    }
+
+    @Override
+    public int getId() {
+        return this.framebuffer.getId();
+    }
+
+    @Override
+    public int getStatus() {
+        this.bind();
+        int status = GLStateManager.glCheckFramebufferStatus(GL30.GL_FRAMEBUFFER);
+        return status;
+    }
+
+    @Override
+    public void addColorAttachment(int i, int i1) {
+        // ignore
+    }
+
+    @Override
+    public void destroy() {
+        // ignore
+        //this.framebuffer.destroy();
+    }
+
+}

src/main/java/net/coderbot/iris/compat/dh/IrisGenericRenderProgram.java

@@ -0,0 +1,351 @@
+package net.coderbot.iris.compat.dh;
+
+import com.google.common.primitives.Ints;
+import com.gtnewhorizons.angelica.glsm.GLStateManager;
+import com.gtnewhorizons.angelica.mixins.interfaces.EntityRendererAccessor;
+import com.mitchej123.lwjgl.MemoryStack;
+import com.seibel.distanthorizons.api.interfaces.override.rendering.IDhApiGenericObjectShaderProgram;
+import com.seibel.distanthorizons.api.interfaces.render.IDhApiRenderableBoxGroup;
+import com.seibel.distanthorizons.api.methods.events.sharedParameterObjects.DhApiRenderParam;
+import com.seibel.distanthorizons.api.objects.math.DhApiMat4f;
+import com.seibel.distanthorizons.api.objects.math.DhApiVec3d;
+import com.seibel.distanthorizons.api.objects.render.DhApiRenderableBox;
+import com.seibel.distanthorizons.api.objects.render.DhApiRenderableBoxGroupShading;
+import net.coderbot.iris.gl.blending.BlendModeOverride;
+import net.coderbot.iris.gl.blending.BufferBlendOverride;
+import net.coderbot.iris.gl.program.ProgramImages;
+import net.coderbot.iris.gl.program.ProgramSamplers;
+import net.coderbot.iris.gl.program.ProgramUniforms;
+import net.coderbot.iris.gl.shader.GlShader;
+import net.coderbot.iris.gl.shader.ShaderType;
+import net.coderbot.iris.gl.state.FogMode;
+import net.coderbot.iris.pipeline.DeferredWorldRenderingPipeline;
+import net.coderbot.iris.pipeline.PatchedShaderPrinter;
+import net.coderbot.iris.pipeline.transform.PatchShaderType;
+import net.coderbot.iris.pipeline.transform.TransformPatcher;
+import net.coderbot.iris.samplers.IrisSamplers;
+import net.coderbot.iris.shaderpack.ProgramSource;
+import net.coderbot.iris.uniforms.CommonUniforms;
+import net.coderbot.iris.uniforms.builtin.BuiltinReplacementUniforms;
+import net.coderbot.iris.uniforms.custom.CustomUniforms;
+import net.irisshaders.iris.api.v0.IrisApi;
+import net.minecraft.client.Minecraft;
+import net.minecraft.client.renderer.texture.DynamicTexture;
+import org.joml.Matrix3f;
+import org.joml.Matrix4f;
+import org.lwjgl.opengl.GL11;
+import org.lwjgl.opengl.GL13;
+import org.lwjgl.opengl.GL15;
+import org.lwjgl.opengl.GL20;
+import org.lwjgl.opengl.GL30;
+
+import java.nio.FloatBuffer;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+public class IrisGenericRenderProgram implements IDhApiGenericObjectShaderProgram {
+    // Uniforms
+    public final int modelViewUniform;
+    public final int modelViewInverseUniform;
+    public final int projectionUniform;
+    public final int projectionInverseUniform;
+    public final int normalMatrix3fUniform;
+    // Fog/Clip Uniforms
+    private final int id;
+    private final ProgramUniforms uniforms;
+    private final CustomUniforms customUniforms;
+    private final ProgramSamplers samplers;
+    private final ProgramImages images;
+    private final BlendModeOverride blend;
+    private final BufferBlendOverride[] bufferBlendOverrides;
+    private final Matrix4f tempModel = new Matrix4f();
+    private final Matrix4f tempProj = new Matrix4f();
+    private final Matrix4f tempMat4 = new Matrix4f();
+    private final Matrix3f tempMat3 = new Matrix3f();
+
+    private final int instancedShaderOffsetChunkUniform;
+    private final int instancedShaderOffsetSubChunkUniform;
+    private final int instancedShaderCameraChunkPosUniform;
+    private final int instancedShaderCameraSubChunkPosUniform;
+    private final int instancedShaderProjectionModelViewMatrixUniform;
+    private final int va;
+    private final int uBlockLight;
+    private final int uSkyLight;
+
+    // This will bind  AbstractVertexAttribute
+    private IrisGenericRenderProgram(String name, boolean isShadowPass, boolean translucent, BlendModeOverride override, BufferBlendOverride[] bufferBlendOverrides, String vertex, String tessControl, String tessEval, String geometry, String fragment, CustomUniforms customUniforms, DeferredWorldRenderingPipeline pipeline) {
+        id = GLStateManager.glCreateProgram();
+
+        GLStateManager.glBindAttribLocation(this.id, 0, "vPosition");
+
+        this.bufferBlendOverrides = bufferBlendOverrides;
+
+        GlShader vert = new GlShader(ShaderType.VERTEX, name + ".vsh", vertex);
+        GLStateManager.glAttachShader(id, vert.getHandle());
+
+        GlShader tessCont = null;
+        if (tessControl != null) {
+            tessCont = new GlShader(ShaderType.TESSELATION_CONTROL, name + ".tcs", tessControl);
+            GLStateManager.glAttachShader(id, tessCont.getHandle());
+        }
+
+        GlShader tessE = null;
+        if (tessEval != null) {
+            tessE = new GlShader(ShaderType.TESSELATION_EVAL, name + ".tes", tessEval);
+            GLStateManager.glAttachShader(id, tessE.getHandle());
+        }
+
+        GlShader geom = null;
+        if (geometry != null) {
+            geom = new GlShader(ShaderType.GEOMETRY, name + ".gsh", geometry);
+            GLStateManager.glAttachShader(id, geom.getHandle());
+        }
+
+        GlShader frag = new GlShader(ShaderType.FRAGMENT, name + ".fsh", fragment);
+        GLStateManager.glAttachShader(id, frag.getHandle());
+
+        GLStateManager.glLinkProgram(this.id);
+        int status = GLStateManager.glGetProgrami(this.id, GL20.GL_LINK_STATUS);
+        if (status != 1) {
+            String message = "Shader link error in Iris DH program! Details: " + GLStateManager.glGetProgramInfoLog(this.id, 9999);
+            this.free();
+            throw new RuntimeException(message);
+        } else {
+            GLStateManager.glUseProgram(this.id);
+        }
+
+        vert.destroy();
+        frag.destroy();
+
+        if (tessCont != null) tessCont.destroy();
+        if (tessE != null) tessE.destroy();
+        if (geom != null) geom.destroy();
+
+        blend = override;
+        ProgramUniforms.Builder uniformBuilder = ProgramUniforms.builder(name, id);
+        ProgramSamplers.Builder samplerBuilder = ProgramSamplers.builder(id, IrisSamplers.WORLD_RESERVED_TEXTURE_UNITS);
+        CommonUniforms.addDynamicUniforms(uniformBuilder, FogMode.PER_VERTEX);
+        customUniforms.assignTo(uniformBuilder);
+        BuiltinReplacementUniforms.addBuiltinReplacementUniforms(uniformBuilder);
+        ProgramImages.Builder builder = ProgramImages.builder(id);
+        pipeline.addGbufferOrShadowSamplers(samplerBuilder, builder,
+            isShadowPass ? pipeline::getFlippedBeforeShadow : () -> translucent ? pipeline.getFlippedAfterTranslucent() : pipeline.getFlippedAfterPrepare(),
+            isShadowPass, true, true, false);
+        customUniforms.mapholderToPass(uniformBuilder, this);
+        this.uniforms = uniformBuilder.buildUniforms();
+        this.customUniforms = customUniforms;
+        samplers = samplerBuilder.build();
+        images = builder.build();
+
+        this.va = GLStateManager.glGenVertexArrays();
+        GLStateManager.glBindVertexArray(va);
+        GLStateManager.glVertexAttribPointer(0, 3, GL11.GL_FLOAT, false, 0, 0);
+        GLStateManager.glEnableVertexAttribArray(0);
+
+        projectionUniform = tryGetUniformLocation2("iris_ProjectionMatrix");
+        projectionInverseUniform = tryGetUniformLocation2("iris_ProjectionMatrixInverse");
+        modelViewUniform = tryGetUniformLocation2("iris_ModelViewMatrix");
+        modelViewInverseUniform = tryGetUniformLocation2("iris_ModelViewMatrixInverse");
+        normalMatrix3fUniform = tryGetUniformLocation2("iris_NormalMatrix");
+
+        this.instancedShaderOffsetChunkUniform = this.tryGetUniformLocation2("uOffsetChunk");
+        this.instancedShaderOffsetSubChunkUniform = this.tryGetUniformLocation2("uOffsetSubChunk");
+        this.instancedShaderCameraChunkPosUniform = this.tryGetUniformLocation2("uCameraPosChunk");
+        this.instancedShaderCameraSubChunkPosUniform = this.tryGetUniformLocation2("uCameraPosSubChunk");
+        this.instancedShaderProjectionModelViewMatrixUniform = this.tryGetUniformLocation2("uProjectionMvm");
+        this.uBlockLight = this.tryGetUniformLocation2("uBlockLight");
+        this.uSkyLight = this.tryGetUniformLocation2("uSkyLight");
+    }
+
+    public static IrisGenericRenderProgram createProgram(String name, boolean isShadowPass, boolean translucent, ProgramSource source, CustomUniforms uniforms, DeferredWorldRenderingPipeline pipeline) {
+        Map<PatchShaderType, String> transformed = TransformPatcher.patchDHGeneric(
+            name,
+            source.getVertexSource().orElseThrow(RuntimeException::new),
+            source.getTessControlSource().orElse(null),
+            source.getTessEvalSource().orElse(null),
+            source.getGeometrySource().orElse(null),
+            source.getFragmentSource().orElseThrow(RuntimeException::new),
+            pipeline.getTextureMap());
+        String vertex = transformed.get(PatchShaderType.VERTEX);
+        String tessControl = transformed.get(PatchShaderType.TESS_CONTROL);
+        String tessEval = transformed.get(PatchShaderType.TESS_EVAL);
+        String geometry = transformed.get(PatchShaderType.GEOMETRY);
+        String fragment = transformed.get(PatchShaderType.FRAGMENT);
+        PatchedShaderPrinter.debugPatchedShaders(source.getName() + "_g", vertex, geometry, tessControl, tessEval, fragment);
+
+        List<BufferBlendOverride> bufferOverrides = new ArrayList<>();
+
+        source.getDirectives().getBufferBlendOverrides().forEach(information -> {
+            int index = Ints.indexOf(source.getDirectives().getDrawBuffers(), information.getIndex());
+            if (index > -1) {
+                bufferOverrides.add(new BufferBlendOverride(index, information.getBlendMode()));
+            }
+        });
+
+        return new IrisGenericRenderProgram(name, isShadowPass, translucent, source.getDirectives().getBlendModeOverride().orElse(null), bufferOverrides.toArray(BufferBlendOverride[]::new), vertex, tessControl, tessEval, geometry, fragment, uniforms, pipeline);
+    }
+
+    // Noise Uniforms
+
+    private static int getChunkPosFromDouble(double value) {
+        return (int) Math.floor(value / 16);
+    }
+
+    private static float getSubChunkPosFromDouble(double value) {
+        double chunkPos = Math.floor(value / 16);
+        return (float) (value - chunkPos * 16);
+    }
+
+    public int tryGetUniformLocation2(CharSequence name) {
+        return GLStateManager.glGetUniformLocation(this.id, name);
+    }
+
+    public void setUniform(int index, Matrix4f matrix) {
+        if (index == -1 || matrix == null) return;
+
+        try (MemoryStack stack = MemoryStack.stackPush()) {
+            FloatBuffer buffer = stack.callocFloat(16);
+            matrix.get(buffer);
+            buffer.rewind();
+
+            GLStateManager.glUniformMatrix4(index, false, buffer);
+        }
+    }
+
+    public void setUniform(int index, Matrix3f matrix) {
+        if (index == -1) return;
+
+        try (MemoryStack stack = MemoryStack.stackPush()) {
+            FloatBuffer buffer = stack.callocFloat(9);
+            matrix.get(buffer);
+            buffer.rewind();
+
+            GLStateManager.glUniformMatrix3(index, false, buffer);
+        }
+    }
+
+    // Override ShaderProgram.bind()
+    public void bind(DhApiRenderParam renderParam) {
+        GLStateManager.glBindVertexArray(va);
+        GLStateManager.glUseProgram(id);
+        if (blend != null) blend.apply();
+
+        for (BufferBlendOverride override : bufferBlendOverrides) {
+            override.apply();
+        }
+
+        toJOML(tempModel, renderParam.dhModelViewMatrix);
+        toJOML(tempProj, renderParam.dhProjectionMatrix);
+
+        setUniform(modelViewUniform, tempModel);
+        setUniform(projectionUniform, tempProj);
+        this.setUniform(this.instancedShaderProjectionModelViewMatrixUniform, tempMat4.set(tempProj).mul(tempModel));
+        tempModel.invert();
+        tempProj.invert();
+        setUniform(modelViewInverseUniform, tempModel);
+        setUniform(projectionInverseUniform, tempProj);
+        setUniform(normalMatrix3fUniform, tempModel.transpose3x3(tempMat3));
+        GLStateManager.glActiveTexture(GL13.GL_TEXTURE0 + IrisSamplers.LIGHTMAP_TEXTURE_UNIT);
+        DynamicTexture lightmapTexture = ((EntityRendererAccessor) Minecraft.getMinecraft().entityRenderer).getLightmapTexture();
+        GLStateManager.glBindTexture(GL11.GL_TEXTURE_2D, lightmapTexture.getGlTextureId());
+
+        samplers.update();
+        uniforms.update();
+
+        customUniforms.push(this);
+
+        images.update();
+    }
+
+    public void unbind() {
+        GLStateManager.glBindVertexArray(0);
+        GLStateManager.glUseProgram(0);
+        ProgramUniforms.clearActiveUniforms();
+        ProgramSamplers.clearActiveSamplers();
+        BlendModeOverride.restore();
+    }
+
+    @Override
+    public void bindVertexBuffer(int i) {
+        GLStateManager.glBindBuffer(GL15.GL_ARRAY_BUFFER, i);
+        GLStateManager.glVertexAttribPointer(0, 3, GL11.GL_FLOAT, false, 12, 0);
+    }
+
+    @Override
+    public boolean overrideThisFrame() {
+        return IrisApi.getInstance().isShaderPackInUse();
+    }
+
+    @Override
+    public int getId() {
+        return id;
+    }
+
+    public void free() {
+        GLStateManager.glDeleteProgram(id);
+    }
+
+    public void fillIndirectUniformData(DhApiRenderParam dhApiRenderParam, DhApiRenderableBoxGroupShading dhApiRenderableBoxGroupShading, IDhApiRenderableBoxGroup boxGroup, DhApiVec3d camPos) {
+        bind(dhApiRenderParam);
+        GLStateManager.enableDepthTest();
+        GLStateManager.glDepthFunc(GL11.GL_LEQUAL);
+        this.setUniform(this.instancedShaderOffsetChunkUniform,
+            getChunkPosFromDouble(boxGroup.getOriginBlockPos().x),
+            getChunkPosFromDouble(boxGroup.getOriginBlockPos().y),
+            getChunkPosFromDouble(boxGroup.getOriginBlockPos().z)
+        );
+        this.setUniform(this.instancedShaderOffsetSubChunkUniform,
+            getSubChunkPosFromDouble(boxGroup.getOriginBlockPos().x),
+            getSubChunkPosFromDouble(boxGroup.getOriginBlockPos().y),
+            getSubChunkPosFromDouble(boxGroup.getOriginBlockPos().z)
+        );
+
+        this.setUniform(this.instancedShaderCameraChunkPosUniform,
+            getChunkPosFromDouble(camPos.x),
+            getChunkPosFromDouble(camPos.y),
+            getChunkPosFromDouble(camPos.z)
+        );
+        this.setUniform(this.instancedShaderCameraSubChunkPosUniform,
+            getSubChunkPosFromDouble(camPos.x),
+            getSubChunkPosFromDouble(camPos.y),
+            getSubChunkPosFromDouble(camPos.z)
+        );
+        this.setUniform(this.uBlockLight,
+            boxGroup.getBlockLight());
+        this.setUniform(this.uSkyLight,
+            boxGroup.getSkyLight());
+
+    }
+
+    @Override
+    public void fillSharedDirectUniformData(DhApiRenderParam dhApiRenderParam, DhApiRenderableBoxGroupShading dhApiRenderableBoxGroupShading, IDhApiRenderableBoxGroup iDhApiRenderableBoxGroup, DhApiVec3d dhApiVec3d) {
+        throw new IllegalStateException("Only indirect is supported with Iris.");
+    }
+
+    @Override
+    public void fillDirectUniformData(DhApiRenderParam dhApiRenderParam, IDhApiRenderableBoxGroup iDhApiRenderableBoxGroup, DhApiRenderableBox dhApiRenderableBox, DhApiVec3d dhApiVec3d) {
+        throw new IllegalStateException("Only indirect is supported with Iris.");
+    }
+
+    private void toJOML(Matrix4f target, DhApiMat4f mat4f) {
+        target.setTransposed(mat4f.getValuesAsArray());
+    }
+
+    private void setUniform(int index, int value) {
+        GLStateManager.glUniform1i(index, value);
+    }
+
+    private void setUniform(int index, float value) {
+        GLStateManager.glUniform1f(index, value);
+    }
+
+    private void setUniform(int index, float x, float y, float z) {
+        GLStateManager.glUniform3f(index, x, y, z);
+    }
+
+    private void setUniform(int index, int x, int y, int z) {
+        GLStateManager.glUniform3i(index, x, y, z);
+    }
+
+}

src/main/java/net/coderbot/iris/compat/dh/IrisLodRenderProgram.java

@@ -0,0 +1,266 @@
+package net.coderbot.iris.compat.dh;
+
+import com.google.common.primitives.Ints;
+import com.gtnewhorizons.angelica.glsm.GLStateManager;
+import com.gtnewhorizons.angelica.mixins.interfaces.EntityRendererAccessor;
+import com.mitchej123.lwjgl.MemoryStack;
+import com.seibel.distanthorizons.api.DhApi;
+import com.seibel.distanthorizons.api.objects.math.DhApiVec3f;
+import net.coderbot.iris.gl.blending.BlendModeOverride;
+import net.coderbot.iris.gl.blending.BufferBlendOverride;
+import net.coderbot.iris.gl.program.ProgramImages;
+import net.coderbot.iris.gl.program.ProgramSamplers;
+import net.coderbot.iris.gl.program.ProgramUniforms;
+import net.coderbot.iris.gl.shader.GlShader;
+import net.coderbot.iris.gl.shader.ShaderType;
+import net.coderbot.iris.gl.state.FogMode;
+import net.coderbot.iris.gl.texture.TextureType;
+import net.coderbot.iris.pipeline.DeferredWorldRenderingPipeline;
+import net.coderbot.iris.pipeline.PatchedShaderPrinter;
+import net.coderbot.iris.pipeline.transform.PatchShaderType;
+import net.coderbot.iris.pipeline.transform.TransformPatcher;
+import net.coderbot.iris.samplers.IrisSamplers;
+import net.coderbot.iris.shaderpack.ProgramSource;
+import net.coderbot.iris.uniforms.CommonUniforms;
+import net.coderbot.iris.uniforms.builtin.BuiltinReplacementUniforms;
+import net.coderbot.iris.uniforms.custom.CustomUniforms;
+import net.minecraft.client.Minecraft;
+import net.minecraft.client.renderer.texture.DynamicTexture;
+import org.joml.Matrix3f;
+import org.joml.Matrix4f;
+import org.joml.Matrix4fc;
+import org.lwjgl.opengl.GL11;
+import org.lwjgl.opengl.GL13;
+import org.lwjgl.opengl.GL20;
+import org.lwjgl.opengl.GL32;
+
+import java.nio.FloatBuffer;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+public class IrisLodRenderProgram {
+    // Uniforms
+    public final int modelOffsetUniform;
+    public final int worldYOffsetUniform;
+    public final int mircoOffsetUniform;
+    public final int modelViewUniform;
+    public final int modelViewInverseUniform;
+    public final int projectionUniform;
+    public final int projectionInverseUniform;
+    public final int normalMatrix3fUniform;
+    // Fog/Clip Uniforms
+    public final int clipDistanceUniform;
+    private final int id;
+    private final ProgramUniforms uniforms;
+    private final CustomUniforms customUniforms;
+    private final ProgramSamplers samplers;
+    private final ProgramImages images;
+    private final BlendModeOverride blend;
+    private final BufferBlendOverride[] bufferBlendOverrides;
+    private final Matrix4f tempMat4a = new Matrix4f();
+    private final Matrix4f tempMat4b = new Matrix4f();
+    private final Matrix3f tempMat3 = new Matrix3f();
+
+    // This will bind  AbstractVertexAttribute
+    private IrisLodRenderProgram(String name, boolean isShadowPass, boolean translucent, BlendModeOverride override, BufferBlendOverride[] bufferBlendOverrides, String vertex, String tessControl, String tessEval, String geometry, String fragment, CustomUniforms customUniforms, DeferredWorldRenderingPipeline pipeline) {
+        id = GLStateManager.glCreateProgram();
+
+        GLStateManager.glBindAttribLocation(this.id, 0, "vPosition");
+        GLStateManager.glBindAttribLocation(this.id, 1, "iris_color");
+        GLStateManager.glBindAttribLocation(this.id, 2, "irisExtra");
+
+        this.bufferBlendOverrides = bufferBlendOverrides;
+
+        GlShader vert = new GlShader(ShaderType.VERTEX, name + ".vsh", vertex);
+        GLStateManager.glAttachShader(id, vert.getHandle());
+
+        GlShader tessCont = null;
+        if (tessControl != null) {
+            tessCont = new GlShader(ShaderType.TESSELATION_CONTROL, name + ".tcs", tessControl);
+            GLStateManager.glAttachShader(id, tessCont.getHandle());
+        }
+
+        GlShader tessE = null;
+        if (tessEval != null) {
+            tessE = new GlShader(ShaderType.TESSELATION_EVAL, name + ".tes", tessEval);
+            GLStateManager.glAttachShader(id, tessE.getHandle());
+        }
+
+        GlShader geom = null;
+        if (geometry != null) {
+            geom = new GlShader(ShaderType.GEOMETRY, name + ".gsh", geometry);
+            GLStateManager.glAttachShader(id, geom.getHandle());
+        }
+
+        GlShader frag = new GlShader(ShaderType.FRAGMENT, name + ".fsh", fragment);
+        GLStateManager.glAttachShader(id, frag.getHandle());
+
+        GLStateManager.glLinkProgram(this.id);
+        int status = GLStateManager.glGetProgrami(this.id, GL20.GL_LINK_STATUS);
+        if (status != 1) {
+            String message = "Shader link error in Iris DH program! Details: " + GLStateManager.glGetProgramInfoLog(this.id, 9999);
+            this.free();
+            throw new RuntimeException(message);
+        } else {
+            GLStateManager.glUseProgram(this.id);
+        }
+
+        vert.destroy();
+        frag.destroy();
+
+        if (tessCont != null) tessCont.destroy();
+        if (tessE != null) tessE.destroy();
+        if (geom != null) geom.destroy();
+
+        blend = override;
+        ProgramUniforms.Builder uniformBuilder = ProgramUniforms.builder(name, id);
+        ProgramSamplers.Builder samplerBuilder = ProgramSamplers.builder(id, IrisSamplers.WORLD_RESERVED_TEXTURE_UNITS);
+        CommonUniforms.addDynamicUniforms(uniformBuilder, FogMode.PER_VERTEX);
+        customUniforms.assignTo(uniformBuilder);
+        BuiltinReplacementUniforms.addBuiltinReplacementUniforms(uniformBuilder);
+        ProgramImages.Builder builder = ProgramImages.builder(id);
+        pipeline.addGbufferOrShadowSamplers(samplerBuilder, builder,
+            isShadowPass ? pipeline::getFlippedBeforeShadow : () -> translucent ? pipeline.getFlippedAfterTranslucent() : pipeline.getFlippedAfterPrepare(),
+            isShadowPass, true, true, false);
+        customUniforms.mapholderToPass(uniformBuilder, this);
+        this.uniforms = uniformBuilder.buildUniforms();
+        this.customUniforms = customUniforms;
+        samplers = samplerBuilder.build();
+        images = builder.build();
+
+        modelOffsetUniform = tryGetUniformLocation2("modelOffset");
+        worldYOffsetUniform = tryGetUniformLocation2("worldYOffset");
+        mircoOffsetUniform = tryGetUniformLocation2("mircoOffset");
+        projectionUniform = tryGetUniformLocation2("iris_ProjectionMatrix");
+        projectionInverseUniform = tryGetUniformLocation2("iris_ProjectionMatrixInverse");
+        modelViewUniform = tryGetUniformLocation2("iris_ModelViewMatrix");
+        modelViewInverseUniform = tryGetUniformLocation2("iris_ModelViewMatrixInverse");
+        normalMatrix3fUniform = tryGetUniformLocation2("iris_NormalMatrix");
+
+        // Fog/Clip Uniforms
+        clipDistanceUniform = tryGetUniformLocation2("clipDistance");
+    }
+
+    public static IrisLodRenderProgram createProgram(String name, boolean isShadowPass, boolean translucent, ProgramSource source, CustomUniforms uniforms, DeferredWorldRenderingPipeline pipeline) {
+        Map<PatchShaderType, String> transformed = TransformPatcher.patchDHTerrain(
+            name,
+            source.getVertexSource().orElseThrow(RuntimeException::new),
+            source.getTessControlSource().orElse(null),
+            source.getTessEvalSource().orElse(null),
+            source.getGeometrySource().orElse(null),
+            source.getFragmentSource().orElseThrow(RuntimeException::new),
+            pipeline.getTextureMap());
+        String vertex = transformed.get(PatchShaderType.VERTEX);
+        String tessControl = transformed.get(PatchShaderType.TESS_CONTROL);
+        String tessEval = transformed.get(PatchShaderType.TESS_EVAL);
+        String geometry = transformed.get(PatchShaderType.GEOMETRY);
+        String fragment = transformed.get(PatchShaderType.FRAGMENT);
+        PatchedShaderPrinter.debugPatchedShaders(source.getName(), vertex, geometry, tessControl, tessEval, fragment);
+
+        List<BufferBlendOverride> bufferOverrides = new ArrayList<>();
+
+        source.getDirectives().getBufferBlendOverrides().forEach(information -> {
+            int index = Ints.indexOf(source.getDirectives().getDrawBuffers(), information.getIndex());
+            if (index > -1) {
+                bufferOverrides.add(new BufferBlendOverride(index, information.getBlendMode()));
+            }
+        });
+
+        return new IrisLodRenderProgram(name, isShadowPass, translucent, source.getDirectives().getBlendModeOverride().orElse(null), bufferOverrides.toArray(BufferBlendOverride[]::new), vertex, tessControl, tessEval, geometry, fragment, uniforms, pipeline);
+    }
+
+    // Noise Uniforms
+
+    public int tryGetUniformLocation2(CharSequence name) {
+        return GLStateManager.glGetUniformLocation(this.id, name);
+    }
+
+    public void setUniform(int index, Matrix4fc matrix) {
+        if (index == -1 || matrix == null) return;
+
+        try (MemoryStack stack = MemoryStack.stackPush()) {
+            FloatBuffer buffer = stack.callocFloat(16);
+            matrix.get(buffer);
+            buffer.rewind();
+
+            GLStateManager.glUniformMatrix4(index, false, buffer);
+        }
+    }
+
+    public void setUniform(int index, Matrix3f matrix) {
+        if (index == -1) return;
+
+        try (MemoryStack stack = MemoryStack.stackPush()) {
+            FloatBuffer buffer = stack.callocFloat(9);
+            matrix.get(buffer);
+            buffer.rewind();
+
+            GLStateManager.glUniformMatrix3(index, false, buffer);
+        }
+    }
+
+    // Override ShaderProgram.bind()
+    public void bind() {
+        GLStateManager.glUseProgram(id);
+        if (blend != null) blend.apply();
+
+        for (BufferBlendOverride override : bufferBlendOverrides) {
+            override.apply();
+        }
+    }
+
+    public void unbind() {
+        GLStateManager.glUseProgram(0);
+        ProgramUniforms.clearActiveUniforms();
+        ProgramSamplers.clearActiveSamplers();
+        BlendModeOverride.restore();
+    }
+
+    public void free() {
+        GLStateManager.glDeleteProgram(id);
+    }
+
+    public void fillUniformData(Matrix4fc projection, Matrix4fc modelView, int worldYOffset, float partialTicks) {
+        GLStateManager.glUseProgram(id);
+
+        GLStateManager.glActiveTexture(GL13.GL_TEXTURE0 + IrisSamplers.LIGHTMAP_TEXTURE_UNIT);
+        DynamicTexture lightmapTexture = ((EntityRendererAccessor) Minecraft.getMinecraft().entityRenderer).getLightmapTexture();
+        GLStateManager.glBindTexture(GL11.GL_TEXTURE_2D, lightmapTexture.getGlTextureId());
+        setUniform(modelViewUniform, modelView);
+        setUniform(modelViewInverseUniform, modelView.invert(tempMat4a));
+        setUniform(projectionUniform, projection);
+        setUniform(projectionInverseUniform, projection.invert(tempMat4b));
+        setUniform(normalMatrix3fUniform, tempMat4a.set(modelView).invert().transpose3x3(tempMat3));
+
+        setUniform(mircoOffsetUniform, 0.01f); // 0.01 block offset
+
+        // setUniform(skyLightUniform, skyLight);
+
+        if (worldYOffsetUniform != -1) setUniform(worldYOffsetUniform, (float) worldYOffset);
+
+        // Fog/Clip Uniforms
+        float dhNearClipDistance = DhApi.Delayed.renderProxy.getNearClipPlaneDistanceInBlocks(partialTicks);
+        setUniform(clipDistanceUniform, dhNearClipDistance);
+
+        samplers.update();
+        uniforms.update();
+
+        customUniforms.push(this);
+
+        images.update();
+    }
+
+    private void setUniform(int index, float value) {
+        GLStateManager.glUniform1f(index, value);
+    }
+
+    public void setModelPos(DhApiVec3f modelPos) {
+        setUniform(modelOffsetUniform, modelPos);
+    }
+
+    private void setUniform(int index, DhApiVec3f pos) {
+        GLStateManager.glUniform3f(index, pos.x, pos.y, pos.z);
+    }
+
+}

src/main/java/net/coderbot/iris/compat/dh/LodRendererEvents.java

@@ -0,0 +1,383 @@
+package net.coderbot.iris.compat.dh;
+
+import com.gtnewhorizons.angelica.glsm.GLStateManager;
+import com.gtnewhorizons.angelica.rendering.RenderingState;
+import com.seibel.distanthorizons.api.DhApi;
+import com.seibel.distanthorizons.api.enums.rendering.EDhApiFogDrawMode;
+import com.seibel.distanthorizons.api.enums.rendering.EDhApiRenderPass;
+import com.seibel.distanthorizons.api.interfaces.override.IDhApiOverrideable;
+import com.seibel.distanthorizons.api.interfaces.override.rendering.IDhApiFramebuffer;
+import com.seibel.distanthorizons.api.interfaces.override.rendering.IDhApiGenericObjectShaderProgram;
+import com.seibel.distanthorizons.api.interfaces.override.rendering.IDhApiShadowCullingFrustum;
+import com.seibel.distanthorizons.api.methods.events.abstractEvents.DhApiAfterDhInitEvent;
+import com.seibel.distanthorizons.api.methods.events.abstractEvents.DhApiBeforeApplyShaderRenderEvent;
+import com.seibel.distanthorizons.api.methods.events.abstractEvents.DhApiBeforeBufferRenderEvent;
+import com.seibel.distanthorizons.api.methods.events.abstractEvents.DhApiBeforeDeferredRenderEvent;
+import com.seibel.distanthorizons.api.methods.events.abstractEvents.DhApiBeforeGenericObjectRenderEvent;
+import com.seibel.distanthorizons.api.methods.events.abstractEvents.DhApiBeforeGenericRenderSetupEvent;
+import com.seibel.distanthorizons.api.methods.events.abstractEvents.DhApiBeforeRenderCleanupEvent;
+import com.seibel.distanthorizons.api.methods.events.abstractEvents.DhApiBeforeRenderEvent;
+import com.seibel.distanthorizons.api.methods.events.abstractEvents.DhApiBeforeRenderPassEvent;
+import com.seibel.distanthorizons.api.methods.events.abstractEvents.DhApiBeforeRenderSetupEvent;
+import com.seibel.distanthorizons.api.methods.events.abstractEvents.DhApiBeforeTextureClearEvent;
+import com.seibel.distanthorizons.api.methods.events.abstractEvents.DhApiColorDepthTextureCreatedEvent;
+import com.seibel.distanthorizons.api.methods.events.sharedParameterObjects.DhApiCancelableEventParam;
+import com.seibel.distanthorizons.api.methods.events.sharedParameterObjects.DhApiEventParam;
+import com.seibel.distanthorizons.api.methods.events.sharedParameterObjects.DhApiRenderParam;
+import com.seibel.distanthorizons.api.objects.math.DhApiVec3f;
+import com.seibel.distanthorizons.coreapi.DependencyInjection.OverrideInjector;
+import net.coderbot.iris.Iris;
+import net.coderbot.iris.pipeline.ShadowRenderer;
+import net.coderbot.iris.pipeline.WorldRenderingPipeline;
+import net.coderbot.iris.shadows.ShadowRenderingState;
+import net.coderbot.iris.uniforms.CapturedRenderingState;
+import net.irisshaders.iris.api.v0.IrisApi;
+import org.joml.Matrix4f;
+import org.lwjgl.opengl.GL11;
+
+public class LodRendererEvents {
+    // TODO: Query actual world min height for Cubic Chunks compatibility
+    private static final int WORLD_MIN_Y = 0;
+
+    private static boolean eventHandlersBound = false;
+
+    private static boolean atTranslucent = false;
+    private static int textureWidth;
+    private static int textureHeight;
+    private static final Matrix4f tempMat4 = new Matrix4f();
+
+
+    // constructor //
+
+    public static void setupEventHandlers() {
+        if (!eventHandlersBound) {
+            eventHandlersBound = true;
+            Iris.logger.info("Queuing DH event binding...");
+
+            DhApiAfterDhInitEvent beforeCleanupEvent = new DhApiAfterDhInitEvent() {
+                @Override
+                public void afterDistantHorizonsInit(DhApiEventParam<Void> event) {
+                    Iris.logger.info("DH Ready, binding Iris event handlers...");
+
+                    Iris.loadShaderpackWhenPossible();
+
+                    setupSetDeferredBeforeRenderingEvent();
+                    setupReconnectDepthTextureEvent();
+                    setupGenericEvent();
+                    setupCreateDepthTextureEvent();
+                    setupTransparentRendererEventCancling();
+                    setupBeforeBufferClearEvent();
+                    setupBeforeRenderCleanupEvent();
+                    beforeBufferRenderEvent();
+                    setupBeforeRenderFrameBufferBinding();
+                    setupBeforeRenderPassEvent();
+                    setupBeforeApplyShaderEvent();
+                    DHCompatInternal.dhEnabled = DhApi.Delayed.configs.graphics().renderingEnabled().getValue();
+                    Iris.logger.info("DH Iris events bound.");
+                }
+            };
+            DhApi.events.bind(DhApiAfterDhInitEvent.class, beforeCleanupEvent);
+        }
+    }
+
+
+    // setup event handlers //
+
+
+    private static void setupSetDeferredBeforeRenderingEvent() {
+        DhApiBeforeRenderEvent beforeRenderEvent = new DhApiBeforeRenderEvent() {
+            // this event is called before DH starts any rendering prep
+            // canceling it will prevent DH from rendering for that frame
+            @Override
+            public void beforeRender(DhApiCancelableEventParam<DhApiRenderParam> event) {
+
+                DhApi.Delayed.renderProxy.setDeferTransparentRendering(IrisApi.getInstance().isShaderPackInUse() && getInstance().shouldOverride);
+                DhApi.Delayed.configs.graphics().fog().drawMode().setValue(getInstance().shouldOverride ? EDhApiFogDrawMode.FOG_DISABLED : EDhApiFogDrawMode.FOG_ENABLED);
+            }
+        };
+
+        DhApi.events.bind(DhApiBeforeRenderEvent.class, beforeRenderEvent);
+    }
+
+    private static void setupReconnectDepthTextureEvent() {
+        DhApiBeforeTextureClearEvent beforeRenderEvent = new DhApiBeforeTextureClearEvent() {
+            @Override
+            public void beforeClear(DhApiCancelableEventParam<DhApiRenderParam> event) {
+                var getResult = DhApi.Delayed.renderProxy.getDhDepthTextureId();
+                if (getResult.success) {
+                    int depthTextureId = getResult.payload;
+                    getInstance().reconnectDHTextures(depthTextureId);
+                }
+            }
+        };
+
+        DhApi.events.bind(DhApiBeforeTextureClearEvent.class, beforeRenderEvent);
+    }
+
+    private static void setupGenericEvent() {
+        DhApiBeforeGenericRenderSetupEvent beforeRenderEvent = new DhApiBeforeGenericRenderSetupEvent() {
+            @Override
+            public void beforeSetup(DhApiEventParam<DhApiRenderParam> dhApiEventParam) {
+                if (getInstance().getGenericFB() != null) {
+                    getInstance().getGenericFB().bind();
+                }
+            }
+        };
+
+        DhApiBeforeGenericObjectRenderEvent beforeDrawEvent = new DhApiBeforeGenericObjectRenderEvent() {
+            @Override
+            public void beforeRender(DhApiCancelableEventParam<EventParam> dhApiCancelableEventParam) {
+                if (dhApiCancelableEventParam.value.resourceLocationPath.equalsIgnoreCase("Clouds")) {
+                    if (getInstance().avoidRenderingClouds()) {
+                        dhApiCancelableEventParam.cancelEvent();
+                    }
+                }
+            }
+        };
+
+        DhApi.events.bind(DhApiBeforeGenericRenderSetupEvent.class, beforeRenderEvent);
+        DhApi.events.bind(DhApiBeforeGenericObjectRenderEvent.class, beforeDrawEvent);
+    }
+
+    private static DHCompatInternal getInstance() {
+        return Iris.getPipelineManager().getPipeline().map(WorldRenderingPipeline::getDHCompat).map(DHCompat::getInstance).orElse(DHCompatInternal.SHADERLESS);
+    }
+
+    private static void setupCreateDepthTextureEvent() {
+        DhApiColorDepthTextureCreatedEvent beforeRenderEvent = new DhApiColorDepthTextureCreatedEvent() {
+            @Override
+            public void onResize(DhApiEventParam<EventParam> input) {
+                textureWidth = input.value.newWidth;
+                textureHeight = input.value.newHeight;
+            }
+        };
+
+        DhApi.events.bind(DhApiColorDepthTextureCreatedEvent.class, beforeRenderEvent);
+    }
+
+    private static void setupTransparentRendererEventCancling() {
+        DhApiBeforeRenderEvent beforeRenderEvent = new DhApiBeforeRenderEvent() {
+            @Override
+            public void beforeRender(DhApiCancelableEventParam<DhApiRenderParam> event) {
+                if (ShadowRenderingState.areShadowsCurrentlyBeingRendered() && (!getInstance().shouldOverrideShadow)) {
+                    event.cancelEvent();
+                }
+            }
+        };
+        DhApiBeforeDeferredRenderEvent beforeRenderEvent2 = new DhApiBeforeDeferredRenderEvent() {
+            @Override
+            public void beforeRender(DhApiCancelableEventParam<DhApiRenderParam> event) {
+                if (ShadowRenderingState.areShadowsCurrentlyBeingRendered() && (!getInstance().shouldOverrideShadow)) {
+                    event.cancelEvent();
+                }
+            }
+        };
+
+        DhApi.events.bind(DhApiBeforeRenderEvent.class, beforeRenderEvent);
+        DhApi.events.bind(DhApiBeforeDeferredRenderEvent.class, beforeRenderEvent2);
+    }
+
+    private static void setupBeforeRenderCleanupEvent() {
+        DhApiBeforeRenderCleanupEvent beforeCleanupEvent = new DhApiBeforeRenderCleanupEvent() {
+            @Override
+            public void beforeCleanup(DhApiEventParam<DhApiRenderParam> event) {
+                if (getInstance().shouldOverride) {
+                    if (ShadowRenderingState.areShadowsCurrentlyBeingRendered()) {
+                        getInstance().getShadowShader().unbind();
+                    } else {
+                        getInstance().getSolidShader().unbind();
+                        if (atTranslucent) {
+                            GLStateManager.enableCull();
+                        }
+                    }
+                }
+            }
+        };
+
+        DhApi.events.bind(DhApiBeforeRenderCleanupEvent.class, beforeCleanupEvent);
+    }
+
+    private static void setupBeforeBufferClearEvent() {
+        DhApiBeforeTextureClearEvent beforeCleanupEvent = new DhApiBeforeTextureClearEvent() {
+            @Override
+            public void beforeClear(DhApiCancelableEventParam<DhApiRenderParam> event) {
+                if (event.value.renderPass == EDhApiRenderPass.OPAQUE) {
+                    if (ShadowRenderingState.areShadowsCurrentlyBeingRendered()) {
+                        event.cancelEvent();
+                    } else if (getInstance().shouldOverride) {
+                        GLStateManager.glClear(GL11.GL_DEPTH_BUFFER_BIT);
+                        event.cancelEvent();
+                    }
+                }
+            }
+        };
+
+        DhApi.events.bind(DhApiBeforeTextureClearEvent.class, beforeCleanupEvent);
+    }
+
+    private static void beforeBufferRenderEvent() {
+        DhApiBeforeBufferRenderEvent beforeCleanupEvent = new DhApiBeforeBufferRenderEvent() {
+            @Override
+            public void beforeRender(DhApiEventParam<EventParam> input) {
+                DHCompatInternal instance = getInstance();
+                if (instance.shouldOverride) {
+                    DhApiVec3f modelPos = input.value.modelPos;
+                    if (ShadowRenderingState.areShadowsCurrentlyBeingRendered()) {
+                        instance.getShadowShader().bind();
+                        instance.getShadowShader().setModelPos(modelPos);
+                    } else if (atTranslucent) {
+                        instance.getTranslucentShader().bind();
+                        instance.getTranslucentShader().setModelPos(modelPos);
+                    } else {
+                        instance.getSolidShader().bind();
+                        instance.getSolidShader().setModelPos(modelPos);
+                    }
+                }
+            }
+        };
+
+        DhApi.events.bind(DhApiBeforeBufferRenderEvent.class, beforeCleanupEvent);
+    }
+
+    private static void setupBeforeRenderFrameBufferBinding() {
+        DhApiBeforeRenderSetupEvent beforeRenderPassEvent = new DhApiBeforeRenderSetupEvent() {
+            @Override
+            public void beforeSetup(DhApiEventParam<DhApiRenderParam> event) {
+                DHCompatInternal instance = getInstance();
+
+                OverrideInjector.INSTANCE.unbind(IDhApiShadowCullingFrustum.class, (IDhApiOverrideable) ShadowRenderer.FRUSTUM);
+                OverrideInjector.INSTANCE.unbind(IDhApiFramebuffer.class, instance.getShadowFBWrapper());
+                OverrideInjector.INSTANCE.unbind(IDhApiFramebuffer.class, instance.getSolidFBWrapper());
+                OverrideInjector.INSTANCE.unbind(IDhApiGenericObjectShaderProgram.class, instance.getGenericShader());
+
+                if (instance.shouldOverride) {
+                    if (instance.getGenericShader() != null) {
+                        OverrideInjector.INSTANCE.bind(IDhApiGenericObjectShaderProgram.class, instance.getGenericShader());
+                    }
+                    if (ShadowRenderingState.areShadowsCurrentlyBeingRendered() && instance.shouldOverrideShadow) {
+                        OverrideInjector.INSTANCE.bind(IDhApiFramebuffer.class, instance.getShadowFBWrapper());
+                        OverrideInjector.INSTANCE.bind(IDhApiShadowCullingFrustum.class, (IDhApiOverrideable) ShadowRenderer.FRUSTUM);
+                    } else {
+                        OverrideInjector.INSTANCE.bind(IDhApiFramebuffer.class, instance.getSolidFBWrapper());
+                    }
+                }
+            }
+        };
+        DhApi.events.bind(DhApiBeforeRenderSetupEvent.class, beforeRenderPassEvent);
+
+    }
+
+    private static void setupBeforeRenderPassEvent() {
+        DhApiBeforeRenderPassEvent beforeCleanupEvent = new DhApiBeforeRenderPassEvent() {
+            @Override
+            public void beforeRender(DhApiEventParam<DhApiRenderParam> event) {
+                DHCompatInternal instance = getInstance();
+
+                // config overrides
+                if (instance.shouldOverride) {
+                    DhApi.Delayed.configs.graphics().ambientOcclusion().enabled().setValue(false);
+                    DhApi.Delayed.configs.graphics().fog().drawMode().setValue(EDhApiFogDrawMode.FOG_DISABLED);
+
+                    if (event.value.renderPass == EDhApiRenderPass.OPAQUE_AND_TRANSPARENT) {
+                        Iris.logger.error("Unexpected; somehow the Opaque + Translucent pass ran with shaders on.");
+                    }
+                } else {
+                    DhApi.Delayed.configs.graphics().ambientOcclusion().enabled().clearValue();
+                    DhApi.Delayed.configs.graphics().fog().drawMode().clearValue();
+                }
+
+
+                // cleanup
+                if (event.value.renderPass == EDhApiRenderPass.OPAQUE) {
+                    if (instance.shouldOverride) {
+                        if (ShadowRenderingState.areShadowsCurrentlyBeingRendered()) {
+                            instance.getShadowShader().bind();
+                        } else {
+                            instance.getSolidShader().bind();
+                        }
+                        atTranslucent = false;
+                    }
+                }
+
+
+                // opaque
+                if (event.value.renderPass == EDhApiRenderPass.OPAQUE) {
+                    float partialTicks = event.value.partialTicks;
+
+                    if (instance.shouldOverride) {
+                        if (ShadowRenderingState.areShadowsCurrentlyBeingRendered()) {
+                            instance.getShadowShader().fillUniformData(
+                                ShadowRenderer.PROJECTION, ShadowRenderer.MODELVIEW,
+                                WORLD_MIN_Y,
+                                partialTicks);
+                        } else {
+                            Matrix4f projection = RenderingState.INSTANCE.getProjectionMatrix();;
+
+                            instance.getSolidShader().fillUniformData(
+                                tempMat4.setPerspective(projection.perspectiveFov(), projection.m11() / projection.m00(), event.value.nearClipPlane, event.value.farClipPlane),
+                                RenderingState.INSTANCE.getModelViewMatrix(),
+                                WORLD_MIN_Y,
+                                partialTicks);
+                        }
+                    }
+                }
+
+
+                // transparent
+                if (event.value.renderPass == EDhApiRenderPass.TRANSPARENT) {
+                    float partialTicks = event.value.partialTicks;
+                    int depthTextureId = DhApi.Delayed.renderProxy.getDhDepthTextureId().payload;
+
+                    if (instance.shouldOverrideShadow && ShadowRenderingState.areShadowsCurrentlyBeingRendered()) {
+                        instance.getShadowShader().bind();
+                        instance.getShadowFB().bind();
+                        atTranslucent = true;
+
+                        return;
+                    }
+
+                    if (instance.shouldOverride && instance.getTranslucentFB() != null) {
+                        instance.copyTranslucents(textureWidth, textureHeight);
+                        instance.getTranslucentShader().bind();
+                        Matrix4f projection = RenderingState.INSTANCE.getProjectionMatrix();
+                        GLStateManager.disableCull();
+
+                        instance.getTranslucentShader().fillUniformData(
+                            new Matrix4f().setPerspective(projection.perspectiveFov(), projection.m11() / projection.m00(), event.value.nearClipPlane, event.value.farClipPlane),
+                            RenderingState.INSTANCE.getModelViewMatrix(),
+                            WORLD_MIN_Y,
+                            partialTicks);
+
+                        instance.getTranslucentFB().bind();
+                    }
+
+                    atTranslucent = true;
+                }
+
+            }
+        };
+
+        DhApi.events.bind(DhApiBeforeRenderPassEvent.class, beforeCleanupEvent);
+    }
+
+    private static void setupBeforeApplyShaderEvent() {
+        DhApiBeforeApplyShaderRenderEvent beforeApplyShaderEvent = new DhApiBeforeApplyShaderRenderEvent() {
+            @Override
+            public void beforeRender(DhApiCancelableEventParam<DhApiRenderParam> event) {
+                if (IrisApi.getInstance().isShaderPackInUse()) {
+                    DHCompatInternal instance = getInstance();
+
+                    OverrideInjector.INSTANCE.unbind(IDhApiShadowCullingFrustum.class, (IDhApiOverrideable) ShadowRenderer.FRUSTUM);
+                    OverrideInjector.INSTANCE.unbind(IDhApiFramebuffer.class, instance.getShadowFBWrapper());
+                    OverrideInjector.INSTANCE.unbind(IDhApiFramebuffer.class, instance.getSolidFBWrapper());
+
+                    event.cancelEvent();
+                }
+            }
+        };
+
+        DhApi.events.bind(DhApiBeforeApplyShaderRenderEvent.class, beforeApplyShaderEvent);
+    }
+
+
+}

src/main/java/net/coderbot/iris/config/IrisConfig.java

@@ -33,12 +33,18 @@ public class IrisConfig {
 	 */
 	private boolean disableUpdateMessage;
 
+	/**
+	 * If debug features should be enabled. Gives much more detailed OpenGL error outputs at the cost of performance.
+	 */
+	private boolean enableDebugOptions;
+
 	private final Path propertiesPath;
 
 	public IrisConfig(Path propertiesPath) {
 		shaderPackName = null;
 		enableShaders = true;
 		disableUpdateMessage = false;
+		enableDebugOptions = false;
 		this.propertiesPath = propertiesPath;
 	}
 
@@ -103,6 +109,10 @@ public class IrisConfig {
 		this.enableShaders = enabled;
 	}
 
+	public boolean areDebugOptionsEnabled() {
+		return enableDebugOptions;
+	}
+
 	/**
 	 * loads the config file and then populates the string, int, and boolean entries with the parsed entries
 	 *
@@ -121,6 +131,7 @@ public class IrisConfig {
 		}
 		shaderPackName = properties.getProperty("shaderPack");
 		enableShaders = !"false".equals(properties.getProperty("enableShaders"));
+		enableDebugOptions = "true".equals(properties.getProperty("enableDebugOptions"));
 		disableUpdateMessage = "true".equals(properties.getProperty("disableUpdateMessage"));
         // TODO: GUI
         try {
@@ -147,6 +158,7 @@ public class IrisConfig {
 		final Properties properties = new Properties();
 		properties.setProperty("shaderPack", getShaderPackName().orElse(""));
 		properties.setProperty("enableShaders", enableShaders ? "true" : "false");
+		properties.setProperty("enableDebugOptions", enableDebugOptions ? "true" : "false");
 		properties.setProperty("disableUpdateMessage", disableUpdateMessage ? "true" : "false");
 		properties.setProperty("maxShadowRenderDistance", String.valueOf(IrisVideoSettings.shadowDistance));
 		// NB: This uses ISO-8859-1 with unicode escapes as the encoding

src/main/java/net/coderbot/iris/gl/framebuffer/GlFramebuffer.java

@@ -45,6 +45,12 @@ public class GlFramebuffer extends GlResource {
 		this.hasDepthAttachment = true;
 	}
 
+	public void addDepthAttachmentBypass(int texture) {
+		final int fb = getGlId();
+		RenderSystem.framebufferTexture2D(fb, GL30.GL_FRAMEBUFFER, GL30.GL_DEPTH_ATTACHMENT, GL11.GL_TEXTURE_2D, texture, 0);
+		this.hasDepthAttachment = true;
+	}
+
 	public void addColorAttachment(int index, int texture) {
         final int fb = getGlId();
 

src/main/java/net/coderbot/iris/gl/shader/StandardMacros.java

@@ -4,6 +4,7 @@ import com.google.common.collect.ImmutableList;
 import com.gtnewhorizons.angelica.Tags;
 import com.gtnewhorizons.angelica.config.AngelicaConfig;
 import cpw.mods.fml.common.Loader;
+import net.coderbot.iris.compat.dh.DHCompat;
 import net.coderbot.iris.parsing.BiomeCategories;
 import net.coderbot.iris.pipeline.HandRenderer;
 import net.coderbot.iris.pipeline.WorldRenderingPhase;
@@ -77,10 +78,32 @@ public class StandardMacros {
 		define(standardDefines, "MC_SPECULAR_MAP");
 		define(standardDefines, "MC_RENDER_QUALITY", "1.0");
 		define(standardDefines, "MC_SHADOW_QUALITY", "1.0");
-        define(standardDefines, "IS_ANGELICA");
-        if (AngelicaConfig.defineIsIris) {
-            define(standardDefines, "IS_IRIS");
-        }
+		define(standardDefines, "IS_ANGELICA");
+		if (AngelicaConfig.defineIsIris) {
+			define(standardDefines, "IS_IRIS");
+		}
+
+		if (DHCompat.hasRenderingEnabled()) {
+			define(standardDefines, "DISTANT_HORIZONS");
+		}
+
+		define(standardDefines, "DH_BLOCK_UNKNOWN", String.valueOf(0));
+		define(standardDefines, "DH_BLOCK_LEAVES", String.valueOf(1));
+		define(standardDefines, "DH_BLOCK_STONE", String.valueOf(2));
+		define(standardDefines, "DH_BLOCK_WOOD", String.valueOf(3));
+		define(standardDefines, "DH_BLOCK_METAL", String.valueOf(4));
+		define(standardDefines, "DH_BLOCK_DIRT", String.valueOf(5));
+		define(standardDefines, "DH_BLOCK_LAVA", String.valueOf(6));
+		define(standardDefines, "DH_BLOCK_DEEPSLATE", String.valueOf(7));
+		define(standardDefines, "DH_BLOCK_SNOW", String.valueOf(8));
+		define(standardDefines, "DH_BLOCK_SAND", String.valueOf(9));
+		define(standardDefines, "DH_BLOCK_TERRACOTTA", String.valueOf(10));
+		define(standardDefines, "DH_BLOCK_NETHER_STONE", String.valueOf(11));
+		define(standardDefines, "DH_BLOCK_WATER", String.valueOf(12));
+		define(standardDefines, "DH_BLOCK_GRASS", String.valueOf(13));
+		define(standardDefines, "DH_BLOCK_AIR", String.valueOf(14));
+		define(standardDefines, "DH_BLOCK_ILLUMINATED", String.valueOf(15));
+
         define(standardDefines, "ANGELICA_VERSION", makeAngelicaVersion());
 		define(standardDefines, "MC_HAND_DEPTH", Float.toString(HandRenderer.DEPTH));
 

src/main/java/net/coderbot/iris/gl/uniform/DynamicLocationalUniformHolder.java

@@ -3,6 +3,7 @@ package net.coderbot.iris.gl.uniform;
 import net.coderbot.iris.gl.state.ValueUpdateNotifier;
 import org.joml.Vector2i;
 import org.joml.Vector3i;
+import org.joml.Vector3ic;
 import org.joml.Vector4f;
 import org.joml.Vector4i;
 
@@ -43,7 +44,7 @@ public interface DynamicLocationalUniformHolder extends LocationalUniformHolder,
 		return this;
 	}
 
-    default DynamicUniformHolder uniform3i(String name, Supplier<Vector3i> value, ValueUpdateNotifier notifier) {
+    default DynamicUniformHolder uniform3i(String name, Supplier<Vector3ic> value, ValueUpdateNotifier notifier) {
         location(name, UniformType.VEC3I).ifPresent(id -> addDynamicUniform(new Vector3IntegerJomlUniform(id, value, notifier), notifier));
 
         return this;

src/main/java/net/coderbot/iris/gl/uniform/DynamicUniformHolder.java

@@ -3,6 +3,7 @@ package net.coderbot.iris.gl.uniform;
 import net.coderbot.iris.gl.state.ValueUpdateNotifier;
 import org.joml.Vector2i;
 import org.joml.Vector3i;
+import org.joml.Vector3ic;
 import org.joml.Vector4f;
 import org.joml.Vector4i;
 
@@ -16,7 +17,7 @@ public interface DynamicUniformHolder extends UniformHolder {
 	DynamicUniformHolder uniform1f(String name, DoubleSupplier value, ValueUpdateNotifier notifier);
 	DynamicUniformHolder uniform1i(String name, IntSupplier value, ValueUpdateNotifier notifier);
 	DynamicUniformHolder uniform2i(String name, Supplier<Vector2i> value, ValueUpdateNotifier notifier);
-    DynamicUniformHolder uniform3i(String name, Supplier<Vector3i> value, ValueUpdateNotifier notifier);
+    DynamicUniformHolder uniform3i(String name, Supplier<Vector3ic> value, ValueUpdateNotifier notifier);
 	DynamicUniformHolder uniform4f(String name, Supplier<Vector4f> value, ValueUpdateNotifier notifier);
     DynamicUniformHolder uniform4fArray(String name, Supplier<float[]> value, ValueUpdateNotifier notifier);
 	DynamicUniformHolder uniform4i(String name, Supplier<Vector4i> value, ValueUpdateNotifier notifier);

src/main/java/net/coderbot/iris/gl/uniform/LocationalUniformHolder.java

@@ -2,11 +2,14 @@ package net.coderbot.iris.gl.uniform;
 
 import net.minecraft.util.Vec3;
 import org.joml.Matrix4f;
+import org.joml.Matrix4fc;
 import org.joml.Vector2f;
 import org.joml.Vector2i;
 import org.joml.Vector3d;
 import org.joml.Vector3f;
+import org.joml.Vector3fc;
 import org.joml.Vector3i;
+import org.joml.Vector3ic;
 import org.joml.Vector4f;
 
 import java.util.OptionalInt;
@@ -70,14 +73,14 @@ public interface LocationalUniformHolder extends UniformHolder {
 	}
 
 	@Override
-	default LocationalUniformHolder uniform3f(UniformUpdateFrequency updateFrequency, String name, Supplier<Vector3f> value) {
+	default LocationalUniformHolder uniform3f(UniformUpdateFrequency updateFrequency, String name, Supplier<Vector3fc> value) {
 		location(name, UniformType.VEC3).ifPresent(id -> addUniform(updateFrequency, new Vector3Uniform(id, value)));
 
 		return this;
 	}
 
     @Override
-    default LocationalUniformHolder uniform3i(UniformUpdateFrequency updateFrequency, String name, Supplier<Vector3i> value) {
+    default LocationalUniformHolder uniform3i(UniformUpdateFrequency updateFrequency, String name, Supplier<Vector3ic> value) {
         location(name, UniformType.VEC3I).ifPresent(id -> addUniform(updateFrequency, new Vector3IntegerJomlUniform(id, value)));
 
         return this;
@@ -119,7 +122,7 @@ public interface LocationalUniformHolder extends UniformHolder {
     }
 
 	@Override
-	default LocationalUniformHolder uniformMatrix(UniformUpdateFrequency updateFrequency, String name, Supplier<Matrix4f> value) {
+	default LocationalUniformHolder uniformMatrix(UniformUpdateFrequency updateFrequency, String name, Supplier<Matrix4fc> value) {
 		location(name, UniformType.MAT4).ifPresent(id -> addUniform(updateFrequency, new MatrixUniform(id, value)));
 
 		return this;

src/main/java/net/coderbot/iris/gl/uniform/MatrixUniform.java

@@ -2,6 +2,7 @@ package net.coderbot.iris.gl.uniform;
 
 import com.gtnewhorizons.angelica.glsm.RenderSystem;
 import org.joml.Matrix4f;
+import org.joml.Matrix4fc;
 import org.lwjgl.BufferUtils;
 
 import java.nio.FloatBuffer;
@@ -10,9 +11,9 @@ import java.util.function.Supplier;
 public class MatrixUniform extends Uniform {
 	private final FloatBuffer buffer = BufferUtils.createFloatBuffer(16);
 	private Matrix4f cachedValue;
-	private final Supplier<Matrix4f> value;
+	private final Supplier<Matrix4fc> value;
 
-	MatrixUniform(int location, Supplier<Matrix4f> value) {
+	MatrixUniform(int location, Supplier<Matrix4fc> value) {
 		super(location);
 
 		this.cachedValue = null;
@@ -21,7 +22,7 @@ public class MatrixUniform extends Uniform {
 
 	@Override
 	public void update() {
-        final Matrix4f newValue = value.get();
+        final Matrix4fc newValue = value.get();
         if( newValue == null ){
             throw new RuntimeException("MatrixUniform value is null");
         }

src/main/java/net/coderbot/iris/gl/uniform/UniformHolder.java

@@ -1,12 +1,13 @@
 package net.coderbot.iris.gl.uniform;
 
 import net.minecraft.util.Vec3;
-import org.joml.Matrix4f;
+import org.joml.Matrix4fc;
 import org.joml.Vector2f;
 import org.joml.Vector2i;
 import org.joml.Vector3d;
-import org.joml.Vector3f;
+import org.joml.Vector3fc;
 import org.joml.Vector3i;
+import org.joml.Vector3ic;
 import org.joml.Vector4f;
 
 import java.util.function.BooleanSupplier;
@@ -29,9 +30,9 @@ public interface UniformHolder {
 
 	UniformHolder uniform2i(UniformUpdateFrequency updateFrequency, String name, Supplier<Vector2i> value);
 
-	UniformHolder uniform3f(UniformUpdateFrequency updateFrequency, String name, Supplier<Vector3f> value);
+	UniformHolder uniform3f(UniformUpdateFrequency updateFrequency, String name, Supplier<Vector3fc> value);
 
-    UniformHolder uniform3i(UniformUpdateFrequency updateFrequency, String name, Supplier<Vector3i> value);
+    UniformHolder uniform3i(UniformUpdateFrequency updateFrequency, String name, Supplier<Vector3ic> value);
 
 	UniformHolder uniformVanilla3f(UniformUpdateFrequency updateFrequency, String name, Supplier<Vec3> value);
 
@@ -43,7 +44,7 @@ public interface UniformHolder {
 
     UniformHolder uniform4fArray(UniformUpdateFrequency updateFrequency, String name, Supplier<float[]> value);
 
-	UniformHolder uniformMatrix(UniformUpdateFrequency updateFrequency, String name, Supplier<Matrix4f> value);
+	UniformHolder uniformMatrix(UniformUpdateFrequency updateFrequency, String name, Supplier<Matrix4fc> value);
 
 	UniformHolder uniformMatrixFromArray(UniformUpdateFrequency updateFrequency, String name, Supplier<float[]> value);
 

src/main/java/net/coderbot/iris/gl/uniform/Vector3IntegerJomlUniform.java

@@ -3,21 +3,22 @@ package net.coderbot.iris.gl.uniform;
 import com.gtnewhorizons.angelica.glsm.RenderSystem;
 import net.coderbot.iris.gl.state.ValueUpdateNotifier;
 import org.joml.Vector3i;
+import org.joml.Vector3ic;
 
 import java.util.function.Supplier;
 
 public class Vector3IntegerJomlUniform extends Uniform {
-    private Vector3i cachedValue;
-    private final Supplier<Vector3i> value;
+    private final Vector3i cachedValue;
+    private final Supplier<Vector3ic> value;
 
-    Vector3IntegerJomlUniform(int location, Supplier<Vector3i> value) {
+    Vector3IntegerJomlUniform(int location, Supplier<Vector3ic> value) {
         this(location, value, null);
     }
 
-    Vector3IntegerJomlUniform(int location, Supplier<Vector3i> value, ValueUpdateNotifier notifier) {
+    Vector3IntegerJomlUniform(int location, Supplier<Vector3ic> value, ValueUpdateNotifier notifier) {
         super(location, notifier);
 
-        this.cachedValue = null;
+        this.cachedValue = new Vector3i();
         this.value = value;
     }
 
@@ -31,11 +32,11 @@ public class Vector3IntegerJomlUniform extends Uniform {
     }
 
     private void updateValue() {
-        Vector3i newValue = value.get();
+        Vector3ic newValue = value.get();
 
-        if (cachedValue == null || !newValue.equals(cachedValue)) {
-            cachedValue = newValue;
-            RenderSystem.uniform3i(this.location, newValue.x, newValue.y, newValue.z);
+        if (!newValue.equals(cachedValue)) {
+            cachedValue.set(newValue.x(), newValue.y(), newValue.z());
+            RenderSystem.uniform3i(this.location, cachedValue.x(), cachedValue.y(), cachedValue.z());
         }
     }
 }

src/main/java/net/coderbot/iris/gl/uniform/Vector3Uniform.java

@@ -3,15 +3,16 @@ package net.coderbot.iris.gl.uniform;
 import com.gtnewhorizons.angelica.glsm.RenderSystem;
 import org.joml.Vector3d;
 import org.joml.Vector3f;
+import org.joml.Vector3fc;
 import org.joml.Vector4f;
 
 import java.util.function.Supplier;
 
 public class Vector3Uniform extends Uniform {
 	private final Vector3f cachedValue;
-	private final Supplier<Vector3f> value;
+	private final Supplier<Vector3fc> value;
 
-	Vector3Uniform(int location, Supplier<Vector3f> value) {
+	Vector3Uniform(int location, Supplier<Vector3fc> value) {
 		super(location);
 
 		this.cachedValue = new Vector3f();
@@ -44,7 +45,7 @@ public class Vector3Uniform extends Uniform {
 
 	@Override
 	public void update() {
-		Vector3f newValue = value.get();
+		Vector3fc newValue = value.get();
 
 		if (!newValue.equals(cachedValue)) {
 			cachedValue.set(newValue.x(), newValue.y(), newValue.z());

src/main/java/net/coderbot/iris/pipeline/DeferredWorldRenderingPipeline.java

@@ -29,12 +29,14 @@ import net.coderbot.iris.gl.buffer.ShaderStorageBufferHolder;
 import net.coderbot.iris.gl.buffer.ShaderStorageInfo;
 import net.coderbot.iris.gl.framebuffer.GlFramebuffer;
 import net.coderbot.iris.gl.image.GlImage;
+import net.coderbot.iris.gl.image.ImageHolder;
 import net.coderbot.iris.gl.image.ImageInformation;
 import net.coderbot.iris.gl.program.ComputeProgram;
 import net.coderbot.iris.gl.program.Program;
 import net.coderbot.iris.gl.program.ProgramBuilder;
 import net.coderbot.iris.gl.program.ProgramImages;
 import net.coderbot.iris.gl.program.ProgramSamplers;
+import net.coderbot.iris.gl.sampler.SamplerHolder;
 import net.coderbot.iris.gl.state.FogMode;
 import net.coderbot.iris.gl.texture.DepthBufferFormat;
 import net.coderbot.iris.gl.texture.TextureType;
@@ -177,6 +179,7 @@ public class DeferredWorldRenderingPipeline implements WorldRenderingPipeline, R
 	private final boolean oldLighting;
 	private final boolean allowConcurrentCompute;
 	private final OptionalInt forcedShadowRenderDistanceChunks;
+	private final CloudSetting dhCloudSetting;
 
 	private Pass current = null;
 
@@ -192,6 +195,7 @@ public class DeferredWorldRenderingPipeline implements WorldRenderingPipeline, R
 	private int currentSpecularTexture;
 	private PackDirectives packDirectives;
 	private final Set<FeatureFlags> activeFeatures;
+	private final ProgramFallbackResolver resolver;
 
 	public DeferredWorldRenderingPipeline(ProgramSet programs) {
 		Objects.requireNonNull(programs);
@@ -206,7 +210,7 @@ public class DeferredWorldRenderingPipeline implements WorldRenderingPipeline, R
 				.map(DeferredWorldRenderingPipeline::submitCompositeTransform)
 				.orElse(null);
 
-		final ProgramFallbackResolver resolver = new ProgramFallbackResolver(programs);
+		resolver = new ProgramFallbackResolver(programs);
 		final Map<Pair<String, InputAvailability>, CompletableFuture<Map<PatchShaderType, String>>> attributeTransformFutures = submitAttributeTransforms(resolver);
 
 		final Optional<ProgramSource> terrainSource = first(programs.getGbuffersTerrain(), programs.getGbuffersTexturedLit(), programs.getGbuffersTextured(), programs.getGbuffersBasic());
@@ -228,6 +232,7 @@ public class DeferredWorldRenderingPipeline implements WorldRenderingPipeline, R
 		this.shouldRenderWeather = programs.getPackDirectives().shouldRenderWeather();
 		this.shouldRenderWeatherParticles = programs.getPackDirectives().shouldRenderWeatherParticles();
 		this.shouldWriteRainAndSnowToDepthBuffer = programs.getPackDirectives().rainDepth();
+		this.dhCloudSetting = programs.getPackDirectives().getDHCloudSetting();
 		this.shouldRenderParticlesBeforeDeferred = programs.getPackDirectives().getParticleRenderingSettings()
 			.map(s -> s == net.coderbot.iris.shaderpack.ParticleRenderingSettings.BEFORE || s == net.coderbot.iris.shaderpack.ParticleRenderingSettings.MIXED)
 			.orElse(false);
@@ -587,7 +592,7 @@ public class DeferredWorldRenderingPipeline implements WorldRenderingPipeline, R
 			renderTargets, flippedAfterPrepare, flippedAfterTranslucent,
 			celeritasShadowFb);
 
-		this.dhCompat = new DHCompat();
+		this.dhCompat = new DHCompat(this, shadowDirectives.isDhShadowEnabled().orElse(true));
 	}
 
 	private RenderTargets getRenderTargets() {
@@ -916,6 +921,38 @@ public class DeferredWorldRenderingPipeline implements WorldRenderingPipeline, R
 		return pass;
 	}
 
+	public void addGbufferOrShadowSamplers(SamplerHolder samplers, ImageHolder images, Supplier<ImmutableSet<Integer>> flipped,
+										   boolean isShadowPass, boolean hasTexture, boolean hasLightmap, boolean hasOverlay) {
+		TextureStage textureStage = TextureStage.GBUFFERS_AND_SHADOW;
+
+		ProgramSamplers.CustomTextureSamplerInterceptor customTextureSamplerInterceptor =
+			ProgramSamplers.customTextureSamplerInterceptor(samplers, customTextureManager.getCustomTextureIdMap(textureStage));
+
+		IrisSamplers.addRenderTargetSamplers(customTextureSamplerInterceptor, flipped, renderTargets, false, this);
+		IrisImages.addRenderTargetImages(images, flipped, renderTargets);
+
+		if (!shouldBindPBR) {
+			shouldBindPBR = IrisSamplers.hasPBRSamplers(customTextureSamplerInterceptor);
+		}
+
+		IrisSamplers.addLevelSamplers(customTextureSamplerInterceptor, this, whitePixel, new InputAvailability(hasTexture, hasLightmap));
+		if (!isShadowPass) {
+			IrisSamplers.addWorldDepthSamplers(customTextureSamplerInterceptor, renderTargets);
+		}
+		IrisSamplers.addNoiseSampler(customTextureSamplerInterceptor, customTextureManager.getNoiseTexture());
+		IrisSamplers.addCustomImages(customTextureSamplerInterceptor, customImages);
+		IrisSamplers.addCustomTextures(customTextureSamplerInterceptor, customTextureManager.getIrisCustomTextures());
+		IrisImages.addCustomImages(images, customImages);
+
+		if (IrisSamplers.hasShadowSamplers(customTextureSamplerInterceptor)) {
+			IrisSamplers.addShadowSamplers(customTextureSamplerInterceptor, shadowTargetsSupplier.get(), null, true);
+		}
+
+		if (isShadowPass || IrisImages.hasShadowImages(images)) {
+			IrisImages.addShadowColorImages(images, shadowTargetsSupplier.get(), null);
+		}
+	}
+
 	private boolean isPostChain;
 	private boolean isMainBound = true;
 
@@ -947,6 +984,56 @@ public class DeferredWorldRenderingPipeline implements WorldRenderingPipeline, R
 		}
 	}
 
+	public CloudSetting getDHCloudSetting() {
+		return dhCloudSetting;
+	}
+
+	public Optional<ProgramSource> getDHTerrainShader() {
+		return resolver.resolve(ProgramId.DhTerrain);
+	}
+
+	public Optional<ProgramSource> getDHGenericShader() {
+		return resolver.resolve(ProgramId.DhGeneric);
+	}
+
+	public Optional<ProgramSource> getDHWaterShader() {
+		return resolver.resolve(ProgramId.DhWater);
+	}
+
+	public Optional<ProgramSource> getDHShadowShader() {
+		return resolver.resolve(ProgramId.DhShadow);
+	}
+
+	public CustomUniforms getCustomUniforms() {
+		return customUniforms;
+	}
+
+	public GlFramebuffer createDHFramebuffer(ProgramSource sources, boolean trans) {
+		return renderTargets.createDHFramebuffer(trans ? flippedAfterTranslucent : flippedAfterPrepare,
+			sources.getDirectives().getDrawBuffers());
+	}
+
+	public ImmutableSet<Integer> getFlippedBeforeShadow() {
+		return flippedBeforeShadow;
+	}
+
+	public ImmutableSet<Integer> getFlippedAfterPrepare() {
+		return flippedAfterPrepare;
+	}
+
+	public ImmutableSet<Integer> getFlippedAfterTranslucent() {
+		return flippedAfterTranslucent;
+	}
+
+	public GlFramebuffer createDHFramebufferShadow(ProgramSource sources) {
+
+		return shadowRenderTargets.createDHFramebuffer(ImmutableSet.of(), new int[]{0, 1});
+	}
+
+	public boolean hasShadowRenderTargets() {
+		return shadowRenderTargets != null;
+	}
+
 	private final class Pass {
 		@Nullable
 		private final Program program;
@@ -1094,6 +1181,7 @@ public class DeferredWorldRenderingPipeline implements WorldRenderingPipeline, R
 		// While it's possible to just clear them instead and reuse them, we'd need to investigate whether or not this
 		// would help performance.
 		renderTargets.destroy();
+		dhCompat.clearPipeline();
 
 		// destroy the shadow render targets
 		if (shadowRenderTargets != null) {

src/main/java/net/coderbot/iris/pipeline/FixedFunctionWorldRenderingPipeline.java

@@ -130,7 +130,7 @@ public class FixedFunctionWorldRenderingPipeline implements WorldRenderingPipeli
 		return new FrameUpdateNotifier();
 	}
 
-	private static final DHCompat DH_COMPAT = new DHCompat();
+	private static final DHCompat DH_COMPAT = new DHCompat(null, false);
 
 	@Override
 	public DHCompat getDHCompat() {

src/main/java/net/coderbot/iris/pipeline/PatchedShaderPrinter.java

@@ -39,6 +39,9 @@ public class PatchedShaderPrinter {
 	}
 
 	public static void debugPatchedShaders(String name, String vertex, String geometry, String tessControl, String tessEval, String fragment, String compute) {
+		if (!Iris.getIrisConfig().areDebugOptionsEnabled()) {
+			return;
+		}
 		if (prettyPrintShaders) {
 			final Path debugOutDir = Minecraft.getMinecraft().mcDataDir.toPath().resolve("patched_shaders");
 			if (!outputLocationCleared) {

src/main/java/net/coderbot/iris/pipeline/ShadowRenderer.java

@@ -10,6 +10,7 @@ import com.gtnewhorizons.angelica.glsm.RenderSystem;
 import com.gtnewhorizons.angelica.rendering.RenderingState;
 import com.gtnewhorizons.angelica.rendering.celeritas.CeleritasWorldRenderer;
 import net.coderbot.iris.Iris;
+import net.coderbot.iris.compat.dh.DHCompat;
 import net.coderbot.iris.gui.option.IrisVideoSettings;
 import net.coderbot.iris.layer.GbufferPrograms;
 import net.coderbot.iris.shaderpack.PackDirectives;
@@ -43,6 +44,7 @@ import net.minecraft.profiler.Profiler;
 import net.minecraft.tileentity.TileEntity;
 import org.embeddedt.embeddium.impl.render.viewport.ViewportProvider;
 import org.joml.Matrix4f;
+import org.joml.Matrix4fc;
 import org.joml.Vector3d;
 import org.joml.Vector3f;
 import org.joml.Vector4f;
@@ -68,6 +70,8 @@ public class ShadowRenderer {
 	public static final List<TileEntity> globalTileEntities = new ArrayList<>();
 	public static boolean ACTIVE = false;
 
+	public static Frustrum FRUSTUM;
+
 	private static final Comparator<Entity> ENTITY_CLASS_COMPARATOR = Comparator.comparingInt(a -> System.identityHashCode(a.getClass()));
 	private static final NonCullingFrustum NON_CULLING_FRUSTUM = new NonCullingFrustum();
 	private static final CullEverythingFrustum CULL_EVERYTHING_FRUSTUM = new CullEverythingFrustum();
@@ -111,12 +115,16 @@ public class ShadowRenderer {
 	private double lastBoxCullerDistance = -1;
 	private double lastAdvancedBoxCullerDistance = -1;
 	private double lastTileEntityCullerDistance = -1;
+	private final boolean shouldRenderDH;
+	private final float nearPlane, farPlane;
 
 	public ShadowRenderer(ProgramSource shadow, PackDirectives directives, ShadowRenderTargets shadowRenderTargets, ShadowCompositeRenderer compositeRenderer) {
 
 		this.profiler = Minecraft.getMinecraft().mcProfiler;
 
 		final PackShadowDirectives shadowDirectives = directives.getShadowDirectives();
+		this.nearPlane = shadowDirectives.getNearPlane();
+		this.farPlane = shadowDirectives.getFarPlane();
 
 		this.halfPlaneLength = shadowDirectives.getDistance();
 		this.voxelDistance = shadowDirectives.getVoxelDistance();
@@ -129,6 +137,7 @@ public class ShadowRenderer {
 		this.shouldRenderEntities = shadowDirectives.shouldRenderEntities();
 		this.shouldRenderPlayer = shadowDirectives.shouldRenderPlayer();
 		this.shouldRenderBlockEntities = shadowDirectives.shouldRenderBlockEntities();
+		this.shouldRenderDH = shadowDirectives.isDhShadowEnabled().orElse(false);
 
 		this.compositeRenderer = compositeRenderer;
 
@@ -348,14 +357,16 @@ public class ShadowRenderer {
 			shadowLightVectorCache.set(shadowLightPosition.x(), shadowLightPosition.y(), shadowLightPosition.z());
 			shadowLightVectorCache.normalize();
 
+			Matrix4fc projView = ((shouldRenderDH && DHCompat.hasRenderingEnabled()) ? DHCompat.getProjection() : RenderingState.INSTANCE.getProjectionMatrix());
+
 			if (hasSafeZone) {
 				BoxCuller distanceCuller = new BoxCuller(halfPlaneLength * renderMultiplier);
 				SafeZoneCullingFrustum safeZoneFrustum = new SafeZoneCullingFrustum(
-					RenderingState.INSTANCE.getModelViewMatrix(), RenderingState.INSTANCE.getProjectionMatrix(),
+					RenderingState.INSTANCE.getModelViewMatrix(), projView,
 					shadowLightVectorCache, boxCuller, distanceCuller);
 				return holder.setInfo(safeZoneFrustum, distanceInfo, cullingInfo);
 			} else {
-				cachedAdvancedFrustum.init(RenderingState.INSTANCE.getModelViewMatrix(), RenderingState.INSTANCE.getProjectionMatrix(), shadowLightVectorCache, boxCuller);
+				cachedAdvancedFrustum.init(RenderingState.INSTANCE.getModelViewMatrix(), projView, shadowLightVectorCache, boxCuller);
 				return holder.setInfo(cachedAdvancedFrustum, distanceInfo, cullingInfo);
 			}
 		}
@@ -630,12 +641,12 @@ public class ShadowRenderer {
 		final MatrixStack modelView = getShadowModelView();
 		MODELVIEW.set(modelView.peek().getModel());
 
-        final Matrix4f shadowProjection;
+		final Matrix4f shadowProjection;
 		if (this.fov != null) {
 			// If FOV is not null, the pack wants a perspective based projection matrix. (This is to support legacy packs)
-            shadowProjection = ShadowMatrices.createPerspectiveMatrix(this.fov);
+			shadowProjection = ShadowMatrices.createPerspectiveMatrix(this.fov);
 		} else {
-            shadowProjection = ShadowMatrices.createOrthoMatrix(halfPlaneLength);
+			shadowProjection = ShadowMatrices.createOrthoMatrix(halfPlaneLength, nearPlane < 0 ? -DHCompat.getRenderDistance() : nearPlane, farPlane < 0 ? DHCompat.getRenderDistance() : farPlane);
 		}
 
 		PROJECTION.set(shadowProjection);
@@ -649,6 +660,7 @@ public class ShadowRenderer {
 		profiler.startSection("initialize frustum");
 
 		terrainFrustumHolder = createShadowFrustum(renderDistanceMultiplier, terrainFrustumHolder);
+		FRUSTUM = terrainFrustumHolder.getFrustum();
 
 		// Use the player/entity position for shadow rendering
 		final Vector3d entityPos = playerCamera.getEntityPos();

src/main/java/net/coderbot/iris/pipeline/transform/DHGenericTransformer.java

@@ -0,0 +1,114 @@
+package net.coderbot.iris.pipeline.transform;
+
+import net.coderbot.iris.gl.shader.ShaderType;
+import net.coderbot.iris.pipeline.transform.parameter.Parameters;
+import org.taumc.glsl.Transformer;
+
+public class DHGenericTransformer {
+    public static void transform(Transformer transformer, Parameters parameters, int glslVersion) {
+        CommonTransformer.transform(transformer, parameters, true, glslVersion);
+
+        transformer.replaceExpression("gl_TextureMatrix[0]", "mat4(1.0)");
+        transformer.replaceExpression("gl_TextureMatrix[1]", "mat4(1.0)");
+        transformer.rename("gl_ProjectionMatrix", "iris_ProjectionMatrix");
+
+        if (parameters.type == ShaderType.VERTEX) {
+            // Alias of gl_MultiTexCoord1 on 1.15+ for OptiFine
+            // See https://github.com/IrisShaders/Iris/issues/1149
+            transformer.rename("gl_MultiTexCoord2", "gl_MultiTexCoord1");
+
+            transformer.replaceExpression("gl_MultiTexCoord0", "vec4(0.0, 0.0, 0.0, 1.0)");
+            transformer.replaceExpression("gl_MultiTexCoord1", "vec4(_vert_tex_light_coord, 0.0, 1.0)");
+
+            replaceGlMultiTexCoordBounded(transformer, 4, 7);
+        }
+
+        transformer.rename("gl_Color", "_vert_color");
+
+        if (parameters.type == ShaderType.VERTEX) {
+            transformer.replaceExpression("gl_Normal", "_vert_normal");
+        }
+
+        transformer.replaceExpression("gl_NormalMatrix", "iris_NormalMatrix");
+        addIfNotExists(transformer, "iris_NormalMatrix", "uniform mat3 iris_NormalMatrix;");
+        addIfNotExists(transformer, "iris_ModelViewMatrixInverse", "uniform mat4 iris_ModelViewMatrixInverse;");
+        addIfNotExists(transformer, "iris_ProjectionMatrixInverse", "uniform mat4 iris_ProjectionMatrixInverse;");
+
+        transformer.rename("gl_ModelViewMatrix", "iris_ModelViewMatrix");
+        transformer.rename("gl_ModelViewMatrixInverse", "iris_ModelViewMatrixInverse");
+        transformer.rename("gl_ProjectionMatrixInverse", "iris_ProjectionMatrixInverse");
+
+        if (parameters.type == ShaderType.VERTEX) {
+            if (transformer.containsCall("ftransform")) {
+                transformer.injectFunction("vec4 ftransform() { return gl_ModelViewProjectionMatrix * gl_Vertex; }");
+            }
+
+            addIfNotExists(transformer, "iris_ProjectionMatrix", "uniform mat4 iris_ProjectionMatrix;");
+            addIfNotExists(transformer, "iris_ModelViewMatrix", "uniform mat4 iris_ModelViewMatrix;");
+            transformer.injectFunction("vec4 getVertexPosition() { return vec4(_vert_position, 1.0); }");
+            transformer.replaceExpression("gl_Vertex", "getVertexPosition()");
+
+            injectVertInit(transformer);
+        } else {
+            addIfNotExists(transformer, "iris_ModelViewMatrix", "uniform mat4 iris_ModelViewMatrix;");
+            addIfNotExists(transformer, "iris_ProjectionMatrix", "uniform mat4 iris_ProjectionMatrix;");
+        }
+
+        transformer.replaceExpression("gl_ModelViewProjectionMatrix", "(iris_ProjectionMatrix * iris_ModelViewMatrix)");
+        ShaderTransformer.applyIntelHd4000Workaround(transformer);
+    }
+
+    public static void injectVertInit(Transformer transformer) {
+        addIfNotExists(transformer, "_vert_position", "vec3 _vert_position;");
+        addIfNotExists(transformer, "_vert_tex_light_coord", "vec2 _vert_tex_light_coord;");
+        addIfNotExists(transformer, "dhMaterialId", "int dhMaterialId;");
+        addIfNotExists(transformer, "_vert_color", "vec4 _vert_color;");
+        addIfNotExists(transformer, "_vert_normal", "vec3 _vert_normal;");
+        addIfNotExists(transformer, "uOffsetChunk", "uniform ivec3 uOffsetChunk;");
+        addIfNotExists(transformer, "uOffsetSubChunk", "uniform vec3 uOffsetSubChunk;");
+        addIfNotExists(transformer, "uCameraPosChunk", "uniform ivec3 uCameraPosChunk;");
+        addIfNotExists(transformer, "uCameraPosSubChunk", "uniform vec3 uCameraPosSubChunk;");
+        addIfNotExists(transformer, "uSkyLight", "uniform int uSkyLight;");
+        addIfNotExists(transformer, "uBlockLight", "uniform int uBlockLight;");
+        addIfNotExists(transformer, "iris_color", "in vec4 iris_color;");
+        addIfNotExists(transformer, "aScale", "in vec3 aScale;");
+        addIfNotExists(transformer, "aTranslateChunk", "in ivec3 aTranslateChunk;");
+        addIfNotExists(transformer, "aTranslateSubChunk", "in vec3 aTranslateSubChunk;");
+        addIfNotExists(transformer, "aMaterial", "in int aMaterial;");
+        addIfNotExists(transformer, "vPosition", "in vec3 vPosition;");
+
+        transformer.injectFunction("const vec3 irisNormals[6] = vec3[](vec3(0,0,-1), vec3(0,0,1), vec3(-1,0,0), vec3(1,0,0), vec3(0,-1,0), vec3(0,1,0));");
+        transformer.injectFunction(
+            "void _vert_init() {"
+                + " vec3 trans = vec3(aTranslateChunk + uOffsetChunk - uCameraPosChunk) * 16.0;"
+                + " trans += (aTranslateSubChunk + uOffsetSubChunk - uCameraPosSubChunk);"
+                + " mat4 transform = mat4("
+                + "  aScale.x, 0.0, 0.0, 0.0,"
+                + "  0.0, aScale.y, 0.0, 0.0,"
+                + "  0.0, 0.0, aScale.z, 0.0,"
+                + "  trans.x, trans.y, trans.z, 1.0"
+                + " );"
+                + " _vert_position = (transform * vec4(vPosition, 1.0)).xyz;"
+                + " _vert_normal = irisNormals[int(floor(float(gl_VertexID) / 4.0))];"
+                + " float blockLight = (float(uBlockLight) + 0.5) / 16.0;"
+                + " float skyLight = (float(uSkyLight) + 0.5) / 16.0;"
+                + " _vert_tex_light_coord = vec2(blockLight, skyLight);"
+                + " dhMaterialId = aMaterial;"
+                + " _vert_color = iris_color;"
+                + " }"
+        );
+        transformer.prependMain("_vert_init();");
+    }
+
+    private static void addIfNotExists(Transformer transformer, String name, String code) {
+        if (!transformer.hasVariable(name)) {
+            transformer.injectVariable(code);
+        }
+    }
+
+    private static void replaceGlMultiTexCoordBounded(Transformer transformer, int from, int to) {
+        for (int i = from; i <= to; i++) {
+            transformer.replaceExpression("gl_MultiTexCoord" + i, "vec4(0.0, 0.0, 0.0, 1.0)");
+        }
+    }
+}

src/main/java/net/coderbot/iris/pipeline/transform/DHTerrainTransformer.java

@@ -0,0 +1,106 @@
+package net.coderbot.iris.pipeline.transform;
+
+import net.coderbot.iris.gl.shader.ShaderType;
+import net.coderbot.iris.pipeline.transform.parameter.Parameters;
+import org.taumc.glsl.Transformer;
+
+public class DHTerrainTransformer {
+    public static void transform(Transformer transformer, Parameters parameters, int glslVersion) {
+        CommonTransformer.transform(transformer, parameters, true, glslVersion);
+
+        transformer.replaceExpression("gl_TextureMatrix[0]", "mat4(1.0)");
+        transformer.replaceExpression("gl_TextureMatrix[1]", "mat4(1.0)");
+        transformer.rename("gl_ProjectionMatrix", "iris_ProjectionMatrix");
+
+        if (parameters.type == ShaderType.VERTEX) {
+            // Alias of gl_MultiTexCoord1 on 1.15+ for OptiFine
+            // See https://github.com/IrisShaders/Iris/issues/1149
+            transformer.rename("gl_MultiTexCoord2", "gl_MultiTexCoord1");
+
+            transformer.replaceExpression("gl_MultiTexCoord0", "vec4(0.0, 0.0, 0.0, 1.0)");
+            transformer.replaceExpression("gl_MultiTexCoord1", "vec4(_vert_tex_light_coord, 0.0, 1.0)");
+
+            replaceGlMultiTexCoordBounded(transformer, 4, 7);
+        }
+
+        transformer.rename("gl_Color", "_vert_color");
+
+        if (parameters.type == ShaderType.VERTEX) {
+            transformer.replaceExpression("gl_Normal", "_vert_normal");
+        }
+
+        transformer.replaceExpression("gl_NormalMatrix", "iris_NormalMatrix");
+        addIfNotExists(transformer, "iris_NormalMatrix", "uniform mat3 iris_NormalMatrix;");
+        addIfNotExists(transformer, "iris_ModelViewMatrixInverse", "uniform mat4 iris_ModelViewMatrixInverse;");
+        addIfNotExists(transformer, "iris_ProjectionMatrixInverse", "uniform mat4 iris_ProjectionMatrixInverse;");
+
+        transformer.rename("gl_ModelViewMatrix", "iris_ModelViewMatrix");
+        transformer.rename("gl_ModelViewMatrixInverse", "iris_ModelViewMatrixInverse");
+        transformer.rename("gl_ProjectionMatrixInverse", "iris_ProjectionMatrixInverse");
+
+        if (parameters.type == ShaderType.VERTEX) {
+            if (transformer.containsCall("ftransform")) {
+                transformer.injectFunction("vec4 ftransform() { return gl_ModelViewProjectionMatrix * gl_Vertex; }");
+            }
+
+            addIfNotExists(transformer, "iris_ProjectionMatrix", "uniform mat4 iris_ProjectionMatrix;");
+            addIfNotExists(transformer, "iris_ModelViewMatrix", "uniform mat4 iris_ModelViewMatrix;");
+            transformer.injectFunction("vec4 getVertexPosition() { return vec4(modelOffset + _vert_position, 1.0); }");
+            transformer.replaceExpression("gl_Vertex", "getVertexPosition()");
+
+            injectVertInit(transformer);
+        } else {
+            addIfNotExists(transformer, "iris_ModelViewMatrix", "uniform mat4 iris_ModelViewMatrix;");
+            addIfNotExists(transformer, "iris_ProjectionMatrix", "uniform mat4 iris_ProjectionMatrix;");
+        }
+
+        transformer.replaceExpression("gl_ModelViewProjectionMatrix", "(iris_ProjectionMatrix * iris_ModelViewMatrix)");
+        ShaderTransformer.applyIntelHd4000Workaround(transformer);
+    }
+
+    public static void injectVertInit(Transformer transformer) {
+        addIfNotExists(transformer, "_vert_position", "vec3 _vert_position;");
+        addIfNotExists(transformer, "_vert_tex_light_coord", "vec2 _vert_tex_light_coord;");
+        addIfNotExists(transformer, "dhMaterialId", "int dhMaterialId;");
+        addIfNotExists(transformer, "_vert_color", "vec4 _vert_color;");
+        addIfNotExists(transformer, "_vert_normal", "vec3 _vert_normal;");
+        addIfNotExists(transformer, "mircoOffset", "uniform float mircoOffset;");
+        addIfNotExists(transformer, "modelOffset", "uniform vec3 modelOffset;");
+        addIfNotExists(transformer, "iris_color", "in vec4 iris_color;");
+        addIfNotExists(transformer, "vPosition", "in uvec4 vPosition;");
+        addIfNotExists(transformer, "irisExtra", "in uvec4 irisExtra;");
+
+        transformer.injectFunction("const vec3 irisNormals[6] = vec3[](vec3(0,-1,0), vec3(0,1,0), vec3(0,0,-1), vec3(0,0,1), vec3(-1,0,0), vec3(1,0,0));");
+        transformer.injectFunction(
+            "void _vert_init() {"
+                + " uint meta = vPosition.a;"
+                + " uint mirco = (meta & 0xFF00u) >> 8u;"
+                + " float mx = (mirco & 1u) != 0u ? mircoOffset : 0.0;"
+                + " mx = (mirco & 2u) != 0u ? -mx : mx;"
+                + " float my = (mirco & 4u) != 0u ? mircoOffset : 0.0;"
+                + " my = (mirco & 8u) != 0u ? -my : my;"
+                + " float mz = (mirco & 16u) != 0u ? mircoOffset : 0.0;"
+                + " mz = (mirco & 32u) != 0u ? -mz : mz;"
+                + " uint lights = meta & 0xFFu;"
+                + " _vert_position = (vPosition.xyz + vec3(mx, my, mz));"
+                + " _vert_normal = irisNormals[int(irisExtra.y)];"
+                + " dhMaterialId = int(irisExtra.x);"
+                + " _vert_tex_light_coord = vec2((float(lights / 16u) + 0.5) / 16.0, (mod(float(lights), 16.0) + 0.5) / 16.0);"
+                + " _vert_color = iris_color;"
+                + " }"
+        );
+        transformer.prependMain("_vert_init();");
+    }
+
+    private static void addIfNotExists(Transformer transformer, String name, String code) {
+        if (!transformer.hasVariable(name)) {
+            transformer.injectVariable(code);
+        }
+    }
+
+    private static void replaceGlMultiTexCoordBounded(Transformer transformer, int from, int to) {
+        for (int i = from; i <= to; i++) {
+            transformer.replaceExpression("gl_MultiTexCoord" + i, "vec4(0.0, 0.0, 0.0, 1.0)");
+        }
+    }
+}

src/main/java/net/coderbot/iris/pipeline/transform/Patch.java

@@ -4,5 +4,7 @@ public enum Patch {
 	ATTRIBUTES,
 	CELERITAS_TERRAIN,
 	COMPOSITE,
-	COMPUTE
+	COMPUTE,
+	DH_TERRAIN,
+	DH_GENERIC
 }

src/main/java/net/coderbot/iris/pipeline/transform/ShaderTransformer.java

@@ -439,6 +439,12 @@ public class ShaderTransformer {
             case COMPUTE:
                 ComputeTransformer.transform(transformer, parameters, versionInt);
                 break;
+            case DH_TERRAIN:
+                DHTerrainTransformer.transform(transformer, parameters, versionInt);
+                break;
+            case DH_GENERIC:
+                DHGenericTransformer.transform(transformer, parameters, versionInt);
+                break;
             default:
                 throw new IllegalStateException("Unknown patch type: " + patchType.name());
         }

src/main/java/net/coderbot/iris/pipeline/transform/TransformPatcher.java

@@ -7,6 +7,7 @@ import net.coderbot.iris.helpers.Tri;
 import net.coderbot.iris.pipeline.transform.parameter.AttributeParameters;
 import net.coderbot.iris.pipeline.transform.parameter.CeleritasTerrainParameters;
 import net.coderbot.iris.pipeline.transform.parameter.ComputeParameters;
+import net.coderbot.iris.pipeline.transform.parameter.DHParameters;
 import net.coderbot.iris.pipeline.transform.parameter.Parameters;
 import net.coderbot.iris.pipeline.transform.parameter.TextureStageParameters;
 import net.coderbot.iris.shaderpack.texture.TextureStage;
@@ -127,6 +128,23 @@ public class TransformPatcher {
         return transform(vertex, geometry, tessControl, tessEval, fragment, new TextureStageParameters(Patch.COMPOSITE, stage, textureMap));
     }
 
+
+    public static Map<PatchShaderType, String> patchDHTerrain(
+        String name, String vertex, String tessControl, String tessEval, String geometry, String fragment,
+        Object2ObjectMap<Tri<String, TextureType, TextureStage>, String> textureMap) {
+        return transform(vertex, geometry, tessControl, tessEval, fragment,
+            new DHParameters(Patch.DH_TERRAIN, textureMap));
+    }
+
+
+    public static Map<PatchShaderType, String> patchDHGeneric(
+        String name, String vertex, String tessControl, String tessEval, String geometry, String fragment,
+        Object2ObjectMap<Tri<String, TextureType, TextureStage>, String> textureMap) {
+        return transform(vertex, geometry, tessControl, tessEval, fragment,
+            new DHParameters(Patch.DH_GENERIC, textureMap));
+
+    }
+
     public static Map<PatchShaderType, String> patchComposite(String vertex, String geometry, String fragment, TextureStage stage, Object2ObjectMap<Tri<String, TextureType, TextureStage>, String> textureMap) {
         return patchComposite(vertex, geometry, null, null, fragment, stage, textureMap);
     }

src/main/java/net/coderbot/iris/pipeline/transform/parameter/DHParameters.java

@@ -0,0 +1,18 @@
+package net.coderbot.iris.pipeline.transform.parameter;
+
+import it.unimi.dsi.fastutil.objects.Object2ObjectMap;
+import net.coderbot.iris.gl.texture.TextureType;
+import net.coderbot.iris.helpers.Tri;
+import net.coderbot.iris.pipeline.transform.Patch;
+import net.coderbot.iris.shaderpack.texture.TextureStage;
+
+public class DHParameters extends Parameters {
+    public DHParameters(Patch patch, Object2ObjectMap<Tri<String, TextureType, TextureStage>, String> textureMap) {
+        super(patch, textureMap);
+    }
+
+    @Override
+    public TextureStage getTextureStage() {
+        return TextureStage.GBUFFERS_AND_SHADOW;
+    }
+}

src/main/java/net/coderbot/iris/rendertarget/RenderTargets.java

@@ -248,6 +248,16 @@ public class RenderTargets {
 		return framebuffer;
 	}
 
+	public GlFramebuffer createDHFramebuffer(ImmutableSet<Integer> stageWritesToAlt, int[] drawBuffers) {
+		if (drawBuffers.length == 0) {
+			return createEmptyFramebuffer();
+		}
+
+		ImmutableSet<Integer> stageWritesToMain = invert(stageWritesToAlt, drawBuffers);
+
+		return createColorFramebuffer(stageWritesToMain, drawBuffers);
+	}
+
 	public GlFramebuffer createGbufferFramebuffer(ImmutableSet<Integer> stageWritesToAlt, int[] drawBuffers) {
 		if (drawBuffers.length == 0) {
 			return createEmptyFramebuffer();

src/main/java/net/coderbot/iris/shaderpack/PackDirectives.java

@@ -28,7 +28,7 @@ public class PackDirectives {
 	@Getter private float eyeBrightnessHalfLife;
 	@Getter private float centerDepthHalfLife;
 	@Getter private CloudSetting cloudSetting;
-	@Getter private CloudSetting dhCloudSetting;
+	private CloudSetting dhCloudSetting;
 	private boolean underwaterOverlay;
 	private boolean vignette;
 	private boolean sun;
@@ -181,6 +181,10 @@ public class PackDirectives {
 		return concurrentCompute;
 	}
 
+	public CloudSetting getDHCloudSetting() {
+		return dhCloudSetting;
+	}
+
     private static float clamp(float val, float lo, float hi) {
 		return Math.max(lo, Math.min(hi, val));
 	}

src/main/java/net/coderbot/iris/shaderpack/PackShadowDirectives.java

@@ -30,6 +30,8 @@ public class PackShadowDirectives {
 	private final boolean shouldRenderPlayer;
 	private final boolean shouldRenderBlockEntities;
 	@Getter private final ShadowCullState cullingState;
+	private final OptionalBoolean dhShadowEnabled;
+	private float nearPlane, farPlane;
 
 	private final ImmutableList<DepthSamplingSettings> depthSamplingSettings;
 	private final ImmutableList<SamplingSettings> colorSamplingSettings;
@@ -53,6 +55,8 @@ public class PackShadowDirectives {
 		// shadowRenderDistanceMul to a nonzero value, since having a high shadow render distance will impact
 		// performance quite heavily on most systems.
 		this.distance = 160.0f;
+		this.nearPlane = 0.05f;
+		this.farPlane = 256.0f;
 		this.voxelDistance = 0.0f;
 
 		// By default, shadows are not culled based on distance from the player. However, pack authors may
@@ -81,6 +85,7 @@ public class PackShadowDirectives {
 		this.shouldRenderBlockEntities = properties.getShadowBlockEntities().orElse(true);
 		this.cullingState = properties.getShadowCulling();
 		this.shadowEnabled = properties.getShadowEnabled();
+		this.dhShadowEnabled = properties.getDhShadowEnabled();
 
 		this.depthSamplingSettings = ImmutableList.of(new DepthSamplingSettings(), new DepthSamplingSettings());
 
@@ -97,6 +102,8 @@ public class PackShadowDirectives {
 		this.resolution = shadowDirectives.resolution;
 		this.fov = shadowDirectives.fov;
 		this.distance = shadowDirectives.distance;
+		this.nearPlane = shadowDirectives.nearPlane;
+		this.farPlane = shadowDirectives.farPlane;
 		this.voxelDistance = shadowDirectives.voxelDistance;
 		this.distanceRenderMul = shadowDirectives.distanceRenderMul;
 		this.entityShadowDistanceMul = shadowDirectives.entityShadowDistanceMul;
@@ -111,6 +118,7 @@ public class PackShadowDirectives {
 		this.depthSamplingSettings = shadowDirectives.depthSamplingSettings;
 		this.colorSamplingSettings = shadowDirectives.colorSamplingSettings;
 		this.shadowEnabled = shadowDirectives.shadowEnabled;
+		this.dhShadowEnabled = shadowDirectives.dhShadowEnabled;
 	}
 
 	public int getResolution() {
@@ -125,6 +133,18 @@ public class PackShadowDirectives {
 		return distance;
 	}
 
+	public float getNearPlane() {
+		return nearPlane;
+	}
+
+	public float getFarPlane() {
+		return farPlane;
+	}
+
+	public OptionalBoolean isDhShadowEnabled() {
+		return dhShadowEnabled;
+	}
+
 	public float getVoxelDistance() {
 		return voxelDistance;
 	}
@@ -186,7 +206,8 @@ public class PackShadowDirectives {
 
 		directives.acceptCommentFloatDirective("SHADOWHPL", distance -> this.distance = distance);
 		directives.acceptConstFloatDirective("shadowDistance", distance -> this.distance = distance);
-
+		directives.acceptConstFloatDirective("shadowNearPlane", nearPlane -> this.nearPlane = nearPlane);
+		directives.acceptConstFloatDirective("shadowFarPlane", farPlane -> this.farPlane = farPlane);
 		directives.acceptConstFloatDirective("entityShadowDistanceMul", distance -> this.entityShadowDistanceMul = distance);
 
 		directives.acceptConstFloatDirective("shadowDistanceRenderMul", distanceRenderMul -> {

src/main/java/net/coderbot/iris/shaderpack/ProgramSet.java

@@ -56,7 +56,10 @@ public class ProgramSet {
 	private final ComputeSource[][] compositeCompute;
 	private final ProgramSource compositeFinal;
 	private final ComputeSource[] finalCompute;
-
+	private final ProgramSource dhTerrain;
+	private final ProgramSource dhGeneric;
+	private final ProgramSource dhWater;
+	private final ProgramSource dhShadow;
 
 	private final ShaderPack pack;
 
@@ -119,6 +122,10 @@ public class ProgramSet {
 		this.gbuffersBlock = readProgramSource(directory, sourceProvider, "gbuffers_block", this, shaderProperties);
 		this.gbuffersBlockTrans = readProgramSource(directory, sourceProvider, "gbuffers_block_translucent", this, shaderProperties);
 		this.gbuffersHand = readProgramSource(directory, sourceProvider, "gbuffers_hand", this, shaderProperties);
+		this.dhTerrain = readProgramSource(directory, sourceProvider, "dh_terrain", this, shaderProperties);
+		this.dhGeneric = readProgramSource(directory, sourceProvider, "dh_generic", this, shaderProperties);
+		this.dhWater = readProgramSource(directory, sourceProvider, "dh_water", this, shaderProperties);
+		this.dhShadow = readProgramSource(directory, sourceProvider, "dh_shadow", this, shaderProperties);
 
 		this.deferred = readProgramArray(directory, sourceProvider, "deferred", shaderProperties);
 		this.deferredCompute = new ComputeSource[deferred.length][];
@@ -219,7 +226,7 @@ public class ProgramSet {
 				gbuffersBasic, gbuffersBeaconBeam, gbuffersTextured, gbuffersTexturedLit, gbuffersTerrain,
 				gbuffersDamagedBlock, gbuffersSkyBasic, gbuffersSkyTextured, gbuffersClouds, gbuffersWeather,
 				gbuffersEntities, gbuffersEntitiesTrans, gbuffersEntitiesGlowing, gbuffersGlint, gbuffersEntityEyes, gbuffersBlock, gbuffersBlockTrans,
-				gbuffersHand
+				gbuffersHand, dhShadow, dhTerrain, dhGeneric, dhWater
 		));
 
 		for (ComputeSource[] computeSources : compositeCompute) {
@@ -387,33 +394,53 @@ public class ProgramSet {
 		return gbuffersHand.requireValid();
 	}
 
+	public Optional<ProgramSource> getDhTerrain() {
+		return dhTerrain.requireValid();
+	}
+
+	public Optional<ProgramSource> getDhGeneric() {
+		return dhGeneric.requireValid();
+	}
+
+	public Optional<ProgramSource> getDhWater() {
+		return dhWater.requireValid();
+	}
+
+	public Optional<ProgramSource> getDhShadow() {
+		return dhShadow.requireValid();
+	}
+
 	public Optional<ProgramSource> get(ProgramId programId) {
-        return switch (programId) {
-            case Shadow -> getShadow();
-            case Basic -> getGbuffersBasic();
-            case Line -> gbuffersLine.requireValid();
-            case Textured -> getGbuffersTextured();
-            case TexturedLit -> getGbuffersTexturedLit();
-            case SkyBasic -> getGbuffersSkyBasic();
-            case SkyTextured -> getGbuffersSkyTextured();
-            case Clouds -> getGbuffersClouds();
-            case Terrain -> getGbuffersTerrain();
-            case DamagedBlock -> getGbuffersDamagedBlock();
-            case Block -> getGbuffersBlock();
+		return switch (programId) {
+			case Shadow -> getShadow();
+			case Basic -> getGbuffersBasic();
+			case Line -> gbuffersLine.requireValid();
+			case Textured -> getGbuffersTextured();
+			case TexturedLit -> getGbuffersTexturedLit();
+			case SkyBasic -> getGbuffersSkyBasic();
+			case SkyTextured -> getGbuffersSkyTextured();
+			case Clouds -> getGbuffersClouds();
+			case Terrain -> getGbuffersTerrain();
+			case DamagedBlock -> getGbuffersDamagedBlock();
+			case Block -> getGbuffersBlock();
             case BlockTrans -> getGbuffersBlockTrans();
-            case BeaconBeam -> getGbuffersBeaconBeam();
-            case Entities -> getGbuffersEntities();
-            case EntitiesTrans -> getGbuffersEntitiesTrans();
-            case EntitiesGlowing -> getGbuffersEntitiesGlowing();
-            case ArmorGlint -> getGbuffersGlint();
-            case SpiderEyes -> getGbuffersEntityEyes();
-            case Hand -> getGbuffersHand();
-            case Weather -> getGbuffersWeather();
-            case Water -> getGbuffersWater();
-            case HandWater -> getGbuffersHandWater();
-            case Final -> getCompositeFinal();
-            default -> Optional.empty();
-        };
+			case BeaconBeam -> getGbuffersBeaconBeam();
+			case Entities -> getGbuffersEntities();
+			case EntitiesTrans -> getGbuffersEntitiesTrans();
+			case EntitiesGlowing -> getGbuffersEntitiesGlowing();
+			case ArmorGlint -> getGbuffersGlint();
+			case SpiderEyes -> getGbuffersEntityEyes();
+			case Hand -> getGbuffersHand();
+			case Weather -> getGbuffersWeather();
+			case Water -> getGbuffersWater();
+			case HandWater -> getGbuffersHandWater();
+			case Final -> getCompositeFinal();
+			case DhTerrain -> getDhTerrain();
+			case DhGeneric -> getDhGeneric();
+			case DhWater -> getDhWater();
+			case DhShadow -> getDhShadow();
+			default -> Optional.empty();
+		};
 	}
 
 	public ProgramSource[] getDeferred() {

src/main/java/net/coderbot/iris/shaderpack/ShaderProperties.java

@@ -495,15 +495,15 @@ public class ShaderProperties {
                 customUniforms.addVariable(parts[0], parts[1], value, false);
             });
 
-            handlePassDirective("uniform.", key, value, pass -> {
-               String[] parts = pass.split("\\.");
-               if (parts.length != 2) {
-                   Iris.logger.warn("Custom uniforms sould take the form of `uniform.<type>.<name> = <expression>. Ignoring " + key);
-                   return;
-               }
+			handlePassDirective("uniform.", key, value, pass -> {
+				String[] parts = pass.split("\\.");
+				if (parts.length != 2) {
+					Iris.logger.warn("Custom uniforms sould take the form of `uniform.<type>.<name> = <expression>. Ignoring " + key);
+					return;
+				}
 
-               customUniforms.addVariable(parts[0], parts[1], value, true);
-            });
+				customUniforms.addVariable(parts[0], parts[1], value, true);
+			});
 
 			// TODO: Buffer size directives
 			// TODO: Conditional program enabling directives

src/main/java/net/coderbot/iris/shaderpack/loading/ProgramGroup.java

@@ -7,7 +7,8 @@ public enum ProgramGroup {
 	Gbuffers("gbuffers"),
 	Deferred("deferred"),
 	Composite("composite"),
-	Final("final")
+	Final("final"),
+	Dh("dh")
 	;
 
 	private final String baseName;

src/main/java/net/coderbot/iris/shaderpack/loading/ProgramId.java

@@ -47,6 +47,10 @@ public enum ProgramId {
 	Weather(ProgramGroup.Gbuffers, "weather", TexturedLit),
 	Water(ProgramGroup.Gbuffers, "water", Terrain),
 	HandWater(ProgramGroup.Gbuffers, "hand_water", Hand),
+	DhTerrain(ProgramGroup.Dh, "terrain"),
+	DhWater(ProgramGroup.Dh, "water", DhTerrain),
+	DhGeneric(ProgramGroup.Dh, "generic", DhTerrain),
+	DhShadow(ProgramGroup.Dh, "shadow"),
 
 	Final(ProgramGroup.Final, ""),
 	;

src/main/java/net/coderbot/iris/shadow/ShadowMatrices.java

@@ -11,16 +11,16 @@ public class ShadowMatrices {
 
 	// NB: These matrices are in column-major order, not row-major order like what you'd expect!
 
-	public static Matrix4f createOrthoMatrix(float halfPlaneLength) {
+	public static Matrix4f createOrthoMatrix(float halfPlaneLength, float nearPlane, float farPlane) {
 		return new Matrix4f(
 				// column 1
 				1.0f / halfPlaneLength, 0f, 0f, 0f,
 				// column 2
 				0f, 1.0f / halfPlaneLength, 0f, 0f,
 				// column 3
-				0f, 0f, 2.0f / (NEAR - FAR), 0f,
+				0f, 0f, 2.0f / (nearPlane - farPlane), 0f,
 				// column 4
-				0f, 0f, -(FAR + NEAR) / (FAR - NEAR), 1f
+				0f, 0f, -(farPlane + nearPlane) / (farPlane - nearPlane), 1f
 		);
 	}
 
@@ -104,7 +104,7 @@ public class ShadowMatrices {
 					0f, 0f, -1.000390648841858f, 1f
 			);
 
-			test("ortho projection hpl=32", expected, createOrthoMatrix(32.0f));
+			test("ortho projection hpl=32", expected, createOrthoMatrix(32.0f, 0.05f, 256.0f));
 
 			// const float shadowDistance = 110.0;
 			// /* SHADOWHPL:110.0 */
@@ -115,7 +115,7 @@ public class ShadowMatrices {
 					0, 0, -1.000390648841858f, 1
 			);
 
-			test("ortho projection hpl=110", expected110, createOrthoMatrix(110.0f));
+			test("ortho projection hpl=110", expected110, createOrthoMatrix(110.0f, 0.05f, 256.0f));
 
 			Matrix4f expected90Proj = new Matrix4f(
 					1.0f, 0.0f, 0.0f, 0.0f,

src/main/java/net/coderbot/iris/shadows/ShadowRenderTargets.java

@@ -206,6 +206,20 @@ public class ShadowRenderTargets {
 		return framebuffer;
 	}
 
+	public GlFramebuffer createDHFramebuffer(ImmutableSet<Integer> stageWritesToAlt, int[] drawBuffers) {
+		if (drawBuffers.length == 0) {
+			return createEmptyFramebuffer();
+		}
+
+		ImmutableSet<Integer> stageWritesToMain = invert(stageWritesToAlt, drawBuffers);
+
+		GlFramebuffer framebuffer = createColorFramebuffer(stageWritesToMain, drawBuffers);
+
+		framebuffer.addDepthAttachment(mainDepth.getTextureId());
+
+		return framebuffer;
+	}
+
 	public GlFramebuffer createShadowFramebuffer(ImmutableSet<Integer> stageWritesToAlt, int[] drawBuffers) {
 		if (drawBuffers.length == 0) {
 			return createEmptyFramebuffer();

src/main/java/net/coderbot/iris/shadows/frustum/CullEverythingFrustum.java

@@ -1,5 +1,8 @@
 package net.coderbot.iris.shadows.frustum;
 
+import cpw.mods.fml.common.Optional;
+import com.seibel.distanthorizons.api.interfaces.override.rendering.IDhApiShadowCullingFrustum;
+import com.seibel.distanthorizons.api.objects.math.DhApiMat4f;
 import net.minecraft.client.renderer.culling.Frustrum;
 import net.minecraft.util.AxisAlignedBB;
 import org.embeddedt.embeddium.impl.render.viewport.Viewport;
@@ -7,7 +10,8 @@ import org.embeddedt.embeddium.impl.render.viewport.ViewportProvider;
 import org.embeddedt.embeddium.impl.render.viewport.frustum.Frustum;
 import org.joml.Vector3d;
 
-public class CullEverythingFrustum extends Frustrum implements ViewportProvider, Frustum {
+@Optional.Interface(modid = "distanthorizons", iface = "com.seibel.distanthorizons.api.interfaces.override.rendering.IDhApiShadowCullingFrustum")
+public class CullEverythingFrustum extends Frustrum implements ViewportProvider, Frustum, IDhApiShadowCullingFrustum {
 	private final Vector3d position = new Vector3d();
 
 	@Override
@@ -24,4 +28,16 @@ public class CullEverythingFrustum extends Frustrum implements ViewportProvider,
 	public Viewport sodium$createViewport() {
 		return new Viewport(this, position.set(xPosition, yPosition, zPosition));
 	}
+
+	@Optional.Method(modid = "distanthorizons")
+	@Override
+	public void update(int worldMinBlockY, int worldMaxBlockY, DhApiMat4f worldViewProjection) {
+
+	}
+
+	@Optional.Method(modid = "distanthorizons")
+	@Override
+	public boolean intersects(int lodBlockPosMinX, int lodBlockPosMinZ, int lodBlockWidth, int lodDetailLevel) {
+		return false;
+	}
 }

src/main/java/net/coderbot/iris/shadows/frustum/advanced/AdvancedShadowCullingFrustum.java

@@ -1,5 +1,8 @@
 package net.coderbot.iris.shadows.frustum.advanced;
 
+import cpw.mods.fml.common.Optional;
+import com.seibel.distanthorizons.api.interfaces.override.rendering.IDhApiShadowCullingFrustum;
+import com.seibel.distanthorizons.api.objects.math.DhApiMat4f;
 import net.coderbot.iris.shadows.frustum.BoxCuller;
 import net.minecraft.client.renderer.culling.Frustrum;
 import net.minecraft.util.AxisAlignedBB;
@@ -8,6 +11,7 @@ import org.embeddedt.embeddium.impl.render.viewport.ViewportProvider;
 import org.embeddedt.embeddium.impl.render.viewport.frustum.Frustum;
 import org.joml.Math;
 import org.joml.Matrix4f;
+import org.joml.Matrix4fc;
 import org.joml.Vector3d;
 import org.joml.Vector3f;
 import org.joml.Vector4f;
@@ -32,7 +36,8 @@ import org.joml.Vector4f;
  * are not sensitive to the specific internal ordering of planes and corners, in order to avoid potential bugs at the
  * cost of slightly more computations.</p>
  */
-public class AdvancedShadowCullingFrustum extends Frustrum implements ViewportProvider, Frustum {
+@Optional.Interface(modid = "distanthorizons", iface = "com.seibel.distanthorizons.api.interfaces.override.rendering.IDhApiShadowCullingFrustum")
+public class AdvancedShadowCullingFrustum extends Frustrum implements ViewportProvider, Frustum, IDhApiShadowCullingFrustum {
 	private static final int MAX_CLIPPING_PLANES = 13;
 
 	/**
@@ -79,6 +84,8 @@ public class AdvancedShadowCullingFrustum extends Frustrum implements ViewportPr
 
 	private final BaseClippingPlanes baseClippingPlanes = new BaseClippingPlanes();
 	private final boolean[] isBackArray = new boolean[6];
+	private int worldMinYDH;
+	private int worldMaxYDH;
 
 	public AdvancedShadowCullingFrustum() {
 		for (int i = 0; i < MAX_CLIPPING_PLANES; i++) {
@@ -86,7 +93,7 @@ public class AdvancedShadowCullingFrustum extends Frustrum implements ViewportPr
 		}
 	}
 
-	public void init(Matrix4f playerView, Matrix4f playerProjection, Vector3f shadowLightVector, BoxCuller boxCuller) {
+	public void init(Matrix4fc playerView, Matrix4fc playerProjection, Vector3f shadowLightVector, BoxCuller boxCuller) {
 		this.shadowLightVectorFromOrigin.set(shadowLightVector);
 		this.boxCuller = boxCuller;
 		this.planeCount = 0;
@@ -298,4 +305,17 @@ public class AdvancedShadowCullingFrustum extends Frustrum implements ViewportPr
 
 		return true;
 	}
+
+	@Optional.Method(modid = "distanthorizons")
+	@Override
+	public void update(int worldMinBlockY, int worldMaxBlockY, DhApiMat4f worldViewProjection) {
+		this.worldMinYDH = worldMinBlockY;
+		this.worldMaxYDH = worldMaxBlockY;
+	}
+
+	@Optional.Method(modid = "distanthorizons")
+	@Override
+	public boolean intersects(int lodBlockPosMinX, int lodBlockPosMinZ, int lodBlockWidth, int lodDetailLevel) {
+		return this.isVisible(lodBlockPosMinX, this.worldMinYDH, lodBlockPosMinZ, lodBlockPosMinX + lodBlockWidth, this.worldMaxYDH, lodBlockPosMinZ + lodBlockWidth);
+	}
 }

src/main/java/net/coderbot/iris/shadows/frustum/advanced/BaseClippingPlanes.java

@@ -1,6 +1,7 @@
 package net.coderbot.iris.shadows.frustum.advanced;
 
 import org.joml.Matrix4f;
+import org.joml.Matrix4fc;
 import org.joml.Vector4f;
 
 public class BaseClippingPlanes {
@@ -13,7 +14,7 @@ public class BaseClippingPlanes {
 		}
 	}
 
-	public void init(Matrix4f view, Matrix4f projection) {
+	public void init(Matrix4fc view, Matrix4fc projection) {
 		// Transform = Transpose(Projection x View)
 		transformScratch.set(projection);
 		transformScratch.mul(view);

src/main/java/net/coderbot/iris/shadows/frustum/advanced/SafeZoneCullingFrustum.java

@@ -3,12 +3,13 @@ package net.coderbot.iris.shadows.frustum.advanced;
 import net.coderbot.iris.shadows.frustum.BoxCuller;
 import net.minecraft.util.AxisAlignedBB;
 import org.joml.Matrix4f;
+import org.joml.Matrix4fc;
 import org.joml.Vector3f;
 
 public class SafeZoneCullingFrustum extends AdvancedShadowCullingFrustum {
 	private final BoxCuller distanceCuller;
 
-	public SafeZoneCullingFrustum(Matrix4f playerView, Matrix4f playerProjection, Vector3f shadowLightVector, BoxCuller voxelCuller, BoxCuller distanceCuller) {
+	public SafeZoneCullingFrustum(Matrix4fc playerView, Matrix4fc playerProjection, Vector3f shadowLightVector, BoxCuller voxelCuller, BoxCuller distanceCuller) {
 		super();
 		init(playerView, playerProjection, shadowLightVector, voxelCuller);
 		this.distanceCuller = distanceCuller;

src/main/java/net/coderbot/iris/shadows/frustum/fallback/BoxCullingFrustum.java

@@ -1,5 +1,8 @@
 package net.coderbot.iris.shadows.frustum.fallback;
 
+import cpw.mods.fml.common.Optional;
+import com.seibel.distanthorizons.api.interfaces.override.rendering.IDhApiShadowCullingFrustum;
+import com.seibel.distanthorizons.api.objects.math.DhApiMat4f;
 import net.coderbot.iris.shadows.frustum.BoxCuller;
 import net.minecraft.client.renderer.culling.Frustrum;
 import net.minecraft.util.AxisAlignedBB;
@@ -8,9 +11,12 @@ import org.embeddedt.embeddium.impl.render.viewport.ViewportProvider;
 import org.embeddedt.embeddium.impl.render.viewport.frustum.Frustum;
 import org.joml.Vector3d;
 
-public class BoxCullingFrustum extends Frustrum implements ViewportProvider, Frustum {
+@Optional.Interface(modid = "distanthorizons", iface = "com.seibel.distanthorizons.api.interfaces.override.rendering.IDhApiShadowCullingFrustum")
+public class BoxCullingFrustum extends Frustrum implements ViewportProvider, Frustum, IDhApiShadowCullingFrustum {
 	private final BoxCuller boxCuller;
 	private final Vector3d position = new Vector3d();
+	private int worldMinYDH;
+	private int worldMaxYDH;
 
 	public BoxCullingFrustum(BoxCuller boxCuller) {
 		this.boxCuller = boxCuller;
@@ -36,4 +42,17 @@ public class BoxCullingFrustum extends Frustrum implements ViewportProvider, Fru
 	public Viewport sodium$createViewport() {
 		return new Viewport(this, position.set(xPosition, yPosition, zPosition));
 	}
+
+	@Optional.Method(modid = "distanthorizons")
+	@Override
+	public void update(int worldMinBlockY, int worldMaxBlockY, DhApiMat4f worldViewProjection) {
+		this.worldMinYDH = worldMinBlockY;
+		this.worldMaxYDH = worldMaxBlockY;
+	}
+
+	@Optional.Method(modid = "distanthorizons")
+	@Override
+	public boolean intersects(int lodBlockPosMinX, int lodBlockPosMinZ, int lodBlockWidth, int lodDetailLevel) {
+		return !boxCuller.isCulled(lodBlockPosMinX, this.worldMinYDH, lodBlockPosMinZ, lodBlockPosMinX + lodBlockWidth, this.worldMaxYDH, lodBlockPosMinZ + lodBlockWidth);
+	}
 }

src/main/java/net/coderbot/iris/shadows/frustum/fallback/NonCullingFrustum.java

@@ -1,5 +1,8 @@
 package net.coderbot.iris.shadows.frustum.fallback;
 
+import cpw.mods.fml.common.Optional;
+import com.seibel.distanthorizons.api.interfaces.override.rendering.IDhApiShadowCullingFrustum;
+import com.seibel.distanthorizons.api.objects.math.DhApiMat4f;
 import net.minecraft.client.renderer.culling.Frustrum;
 import net.minecraft.util.AxisAlignedBB;
 import org.embeddedt.embeddium.impl.render.viewport.Viewport;
@@ -7,7 +10,8 @@ import org.embeddedt.embeddium.impl.render.viewport.ViewportProvider;
 import org.embeddedt.embeddium.impl.render.viewport.frustum.Frustum;
 import org.joml.Vector3d;
 
-public class NonCullingFrustum extends Frustrum implements ViewportProvider, Frustum {
+@Optional.Interface(modid = "distanthorizons", iface = "com.seibel.distanthorizons.api.interfaces.override.rendering.IDhApiShadowCullingFrustum")
+public class NonCullingFrustum extends Frustrum implements ViewportProvider, Frustum, IDhApiShadowCullingFrustum {
 	private final Vector3d position = new Vector3d();
 
 	@Override
@@ -24,4 +28,17 @@ public class NonCullingFrustum extends Frustrum implements ViewportProvider, Fru
 	public Viewport sodium$createViewport() {
 		return new Viewport(this, position.set(xPosition, yPosition, zPosition));
 	}
+
+	@Optional.Method(modid = "distanthorizons")
+	@Override
+	public void update(int worldMinBlockY, int worldMaxBlockY, DhApiMat4f worldViewProjection) {
+
+	}
+
+	@Optional.Method(modid = "distanthorizons")
+	@Override
+	public boolean intersects(int lodBlockPosMinX, int lodBlockPosMinZ, int lodBlockWidth, int lodDetailLevel) {
+		return true;
+	}
+
 }

src/main/java/net/coderbot/iris/uniforms/CameraUniforms.java

@@ -4,8 +4,12 @@ import com.gtnewhorizons.angelica.rendering.RenderingState;
 import lombok.Getter;
 import net.coderbot.iris.gl.uniform.UniformHolder;
 import net.minecraft.client.Minecraft;
+import org.joml.Matrix3f;
 import org.joml.Vector3d;
-import org.joml.Vector3dc;
+import org.joml.Vector3f;
+import org.joml.Vector3fc;
+import org.joml.Vector3i;
+import org.joml.Vector3ic;
 
 import static net.coderbot.iris.gl.uniform.UniformUpdateFrequency.ONCE;
 import static net.coderbot.iris.gl.uniform.UniformUpdateFrequency.PER_FRAME;
@@ -15,6 +19,8 @@ import static net.coderbot.iris.gl.uniform.UniformUpdateFrequency.PER_FRAME;
  */
 public class CameraUniforms {
 	private static final Minecraft client = Minecraft.getMinecraft();
+	private static final Vector3f tempVec3f = new Vector3f();
+	private static final Vector3i tempVec3i = new Vector3i();
 
 	private CameraUniforms() {
 	}
@@ -27,7 +33,27 @@ public class CameraUniforms {
 			.uniform1f(PER_FRAME, "far", CameraUniforms::getRenderDistanceInBlocks)
 			.uniform3d(PER_FRAME, "cameraPosition", tracker::getCurrentCameraPosition)
 			.uniform1f(PER_FRAME, "eyeAltitude", tracker::getCurrentCameraPositionY)
-			.uniform3d(PER_FRAME, "previousCameraPosition", tracker::getPreviousCameraPosition);
+			.uniform3d(PER_FRAME, "previousCameraPosition", tracker::getPreviousCameraPosition)
+			.uniform3i(PER_FRAME, "cameraPositionInt", () -> getCameraPositionInt(getUnshiftedCameraPosition()))
+			.uniform3f(PER_FRAME, "cameraPositionFract", () -> getCameraPositionFract(getUnshiftedCameraPosition()))
+			.uniform3i(PER_FRAME, "previousCameraPositionInt", () -> getCameraPositionInt(tracker.getPreviousCameraPositionUnshifted()))
+			.uniform3f(PER_FRAME, "previousCameraPositionFract", () -> getCameraPositionFract(tracker.getPreviousCameraPositionUnshifted()));
+	}
+
+	public static Vector3fc getCameraPositionFract(Vector3d originalPos) {
+		return tempVec3f.set(
+			(float) (originalPos.x - Math.floor(originalPos.x)),
+			(float) (originalPos.y - Math.floor(originalPos.y)),
+			(float) (originalPos.z - Math.floor(originalPos.z))
+		);
+	}
+
+	public static Vector3ic getCameraPositionInt(Vector3d originalPos) {
+		return tempVec3i.set(
+			(int) Math.floor(originalPos.x),
+			(int) Math.floor(originalPos.y),
+			(int) Math.floor(originalPos.z)
+		);
 	}
 
 	private static int getRenderDistanceInBlocks() {
@@ -35,7 +61,7 @@ public class CameraUniforms {
 		return client.gameSettings.renderDistanceChunks * 16;
 	}
 
-	public static Vector3dc getUnshiftedCameraPosition() {
+	public static Vector3d getUnshiftedCameraPosition() {
         return RenderingState.INSTANCE.getCameraPosition();
 	}
 
@@ -50,10 +76,12 @@ public class CameraUniforms {
 		private static final double TP_RANGE = 1000;
 
 		@Getter
-        private Vector3d previousCameraPosition = new Vector3d();
+		private Vector3d previousCameraPosition = new Vector3d();
 		@Getter
-        private Vector3d currentCameraPosition = new Vector3d();
+		private Vector3d currentCameraPosition = new Vector3d();
 		private final Vector3d shift = new Vector3d();
+		private Vector3d previousCameraPositionUnshifted = new Vector3d();
+		private Vector3d currentCameraPositionUnshifted = new Vector3d();
 
 		CameraPositionTracker(FrameUpdateNotifier notifier) {
 			notifier.addListener(this::update);
@@ -61,7 +89,9 @@ public class CameraUniforms {
 
 		private void update() {
 			previousCameraPosition.set(currentCameraPosition);
+			previousCameraPositionUnshifted = currentCameraPositionUnshifted;
 			currentCameraPosition.set(getUnshiftedCameraPosition()).add(shift);
+			currentCameraPositionUnshifted.set(getUnshiftedCameraPosition());
 
 			updateShift();
 		}
@@ -104,8 +134,12 @@ public class CameraUniforms {
 			previousCameraPosition.z += dZ;
 		}
 
-        public double getCurrentCameraPositionY() {
+		public double getCurrentCameraPositionY() {
 			return currentCameraPosition.y;
 		}
+
+		public Vector3d getPreviousCameraPositionUnshifted() {
+			return previousCameraPositionUnshifted;
+		}
 	}
 }

src/main/java/net/coderbot/iris/uniforms/CommonUniforms.java

@@ -7,6 +7,7 @@ import com.gtnewhorizons.angelica.glsm.texture.TextureInfo;
 import com.gtnewhorizons.angelica.glsm.texture.TextureInfoCache;
 import com.gtnewhorizons.angelica.client.rendering.TextureTracker;
 import com.gtnewhorizons.angelica.mixins.interfaces.EntityRendererAccessor;
+import net.coderbot.iris.compat.dh.DHCompat;
 import net.coderbot.iris.gl.state.FogMode;
 import net.coderbot.iris.gl.state.ValueUpdateNotifier;
 import net.coderbot.iris.gl.uniform.DynamicUniformHolder;
@@ -137,7 +138,10 @@ public final class CommonUniforms {
 			.uniform1f(PER_TICK, "rainStrength", CommonUniforms::getRainStrength)
 			.uniform1f(PER_TICK, "wetness", new SmoothedFloat(directives.getWetnessHalfLife(), directives.getDrynessHalfLife(), CommonUniforms::getRainStrength, updateNotifier))
 			.uniform3d(PER_FRAME, "skyColor", CommonUniforms::getSkyColor)
-			.uniform3d(PER_FRAME, "fogColor", GLStateManager::getFogColor);
+			.uniform3d(PER_FRAME, "fogColor", GLStateManager::getFogColor)
+			.uniform1f(PER_FRAME, "dhFarPlane", DHCompat::getFarPlane)
+			.uniform1f(PER_FRAME, "dhNearPlane", DHCompat::getNearPlane)
+			.uniform1i(PER_FRAME, "dhRenderDistance", DHCompat::getRenderDistance);
 	}
 
     private static boolean isOnGround() {

src/main/java/net/coderbot/iris/uniforms/MatrixUniforms.java

@@ -1,11 +1,13 @@
 package net.coderbot.iris.uniforms;
 
 import com.gtnewhorizons.angelica.rendering.RenderingState;
+import net.coderbot.iris.compat.dh.DHCompat;
 import net.coderbot.iris.gl.uniform.UniformHolder;
 import net.coderbot.iris.pipeline.ShadowRenderer;
 import net.coderbot.iris.shaderpack.PackDirectives;
 import net.coderbot.iris.shadow.ShadowMatrices;
 import org.joml.Matrix4f;
+import org.joml.Matrix4fc;
 
 import java.util.function.Supplier;
 
@@ -20,27 +22,37 @@ public final class MatrixUniforms {
 		// TODO: In some cases, gbufferProjectionInverse takes on a value much different than OptiFine...
 		// We need to audit Mojang's linear algebra.
 		addMatrix(uniforms, "Projection", RenderingState.INSTANCE::getProjectionMatrix);
+		addDHMatrix(uniforms, "Projection", DHCompat::getProjection);
 		addShadowMatrix(uniforms, "ModelView", () -> ShadowRenderer.createShadowModelView(directives.getSunPathRotation(), directives.getShadowDirectives().getIntervalSize()).peek().getModel());
-        addShadowMatrix(uniforms, "Projection", () -> ShadowMatrices.createOrthoMatrix(directives.getShadowDirectives().getDistance()));
+		addShadowMatrix(uniforms, "Projection", () -> ShadowMatrices.createOrthoMatrix(directives.getShadowDirectives().getDistance(), directives.getShadowDirectives().getNearPlane() < 0 ? -DHCompat.getRenderDistance() : directives.getShadowDirectives().getNearPlane(),
+			directives.getShadowDirectives().getFarPlane() < 0 ? DHCompat.getRenderDistance() : directives.getShadowDirectives().getFarPlane()));
 	}
 
-	private static void addMatrix(UniformHolder uniforms, String name, Supplier<Matrix4f> supplier) {
+	private static void addMatrix(UniformHolder uniforms, String name, Supplier<Matrix4fc> supplier) {
 		uniforms
 			.uniformMatrix(PER_FRAME, "gbuffer" + name, supplier)
 			.uniformMatrix(PER_FRAME, "gbuffer" + name + "Inverse", new Inverted(supplier))
 			.uniformMatrix(PER_FRAME, "gbufferPrevious" + name, new Previous(supplier));
 	}
 
-	private static void addShadowMatrix(UniformHolder uniforms, String name, Supplier<Matrix4f> supplier) {
+	private static void addDHMatrix(UniformHolder uniforms, String name, Supplier<Matrix4fc> supplier) {
+		uniforms
+			.uniformMatrix(PER_FRAME, "dh" + name, supplier)
+			.uniformMatrix(PER_FRAME, "dh" + name + "Inverse", new Inverted(supplier))
+			.uniformMatrix(PER_FRAME, "dhPrevious" + name, new Previous(supplier));
+	}
+
+
+	private static void addShadowMatrix(UniformHolder uniforms, String name, Supplier<Matrix4fc> supplier) {
 		uniforms
 				.uniformMatrix(PER_FRAME, "shadow" + name, supplier)
 				.uniformMatrix(PER_FRAME, "shadow" + name + "Inverse", new Inverted(supplier));
 	}
 
-	private static class Inverted implements Supplier<Matrix4f> {
-		private final Supplier<Matrix4f> parent;
+	private static class Inverted implements Supplier<Matrix4fc> {
+		private final Supplier<Matrix4fc> parent;
 
-		Inverted(Supplier<Matrix4f> parent) {
+		Inverted(Supplier<Matrix4fc> parent) {
 			this.parent = parent;
 		}
 
@@ -56,11 +68,11 @@ public final class MatrixUniforms {
 	}
 
 
-	private static class Previous implements Supplier<Matrix4f> {
-		private final Supplier<Matrix4f> parent;
-		private Matrix4f previous;
+	private static class Previous implements Supplier<Matrix4fc> {
+		private final Supplier<Matrix4fc> parent;
+		private Matrix4fc previous;
 
-		Previous(Supplier<Matrix4f> parent) {
+		Previous(Supplier<Matrix4fc> parent) {
 			this.parent = parent;
 			this.previous = new Matrix4f();
 		}

src/main/java/net/coderbot/iris/uniforms/custom/CustomUniformFixedInputUniformsHolder.java

@@ -25,7 +25,8 @@ import org.joml.Vector2f;
 import org.joml.Vector2i;
 import org.joml.Vector3d;
 import org.joml.Vector3f;
-import org.joml.Vector3i;
+import org.joml.Vector3fc;
+import org.joml.Vector3ic;
 import org.joml.Vector4f;
 
 import java.util.Collection;
@@ -116,12 +117,12 @@ public class CustomUniformFixedInputUniformsHolder {
 		}
 
 		@Override
-		public Builder uniform3f(UniformUpdateFrequency updateFrequency, String name, Supplier<Vector3f> value) {
+		public Builder uniform3f(UniformUpdateFrequency updateFrequency, String name, Supplier<Vector3fc> value) {
 			return this.put(name, new Float3VectorCachedUniform(name, updateFrequency, value));
 		}
 
 		@Override
-		public Builder uniform3i(UniformUpdateFrequency updateFrequency, String name, Supplier<Vector3i> value) {
+		public Builder uniform3i(UniformUpdateFrequency updateFrequency, String name, Supplier<Vector3ic> value) {
 			return this.put(name, new Int3VectorCachedUniform(name, updateFrequency, value));
 		}
 
@@ -172,7 +173,7 @@ public class CustomUniformFixedInputUniformsHolder {
 
 		@Override
 		public UniformHolder uniformMatrix(
-			UniformUpdateFrequency updateFrequency, String name, Supplier<Matrix4f> value) {
+			UniformUpdateFrequency updateFrequency, String name, Supplier<Matrix4fc> value) {
 			return this.put(name, new Float4MatrixCachedUniform(name, updateFrequency, value));
 		}
 

src/main/java/net/coderbot/iris/uniforms/custom/cached/Float3VectorCachedUniform.java

@@ -4,23 +4,24 @@ import net.coderbot.iris.gl.uniform.UniformUpdateFrequency;
 import net.coderbot.iris.parsing.VectorType;
 import org.joml.Vector3f;
 import com.gtnewhorizons.angelica.glsm.GLStateManager;
+import org.joml.Vector3fc;
 
 import java.util.function.Supplier;
 
-public class Float3VectorCachedUniform extends VectorCachedUniform<Vector3f> {
+public class Float3VectorCachedUniform extends VectorCachedUniform<Vector3fc> {
 
-	public Float3VectorCachedUniform(String name, UniformUpdateFrequency updateFrequency, Supplier<Vector3f> supplier) {
+	public Float3VectorCachedUniform(String name, UniformUpdateFrequency updateFrequency, Supplier<Vector3fc> supplier) {
 		super(name, updateFrequency, new Vector3f(), supplier);
 	}
 
 	@Override
-	protected void setFrom(Vector3f other) {
-		this.cached.set(other);
+	protected void setFrom(Vector3fc other) {
+		((Vector3f)this.cached).set(other);
 	}
 
 	@Override
 	public void push(int location) {
-		GLStateManager.glUniform3f(location, this.cached.x, this.cached.y, this.cached.z);
+		GLStateManager.glUniform3f(location, this.cached.x(), this.cached.y(), this.cached.z());
 	}
 
 	@Override

src/main/java/net/coderbot/iris/uniforms/custom/cached/Float4MatrixCachedUniform.java

@@ -4,21 +4,22 @@ import net.coderbot.iris.gl.uniform.UniformUpdateFrequency;
 import net.coderbot.iris.parsing.MatrixType;
 import org.joml.Matrix4f;
 import com.gtnewhorizons.angelica.glsm.GLStateManager;
+import org.joml.Matrix4fc;
 
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.nio.FloatBuffer;
 import java.util.function.Supplier;
 
-public class Float4MatrixCachedUniform extends VectorCachedUniform<Matrix4f> {
+public class Float4MatrixCachedUniform extends VectorCachedUniform<Matrix4fc> {
 	final private FloatBuffer buffer = ByteBuffer.allocateDirect(16 << 2).order(ByteOrder.nativeOrder()).asFloatBuffer();
 
-	public Float4MatrixCachedUniform(String name, UniformUpdateFrequency updateFrequency, Supplier<Matrix4f> supplier) {
+	public Float4MatrixCachedUniform(String name, UniformUpdateFrequency updateFrequency, Supplier<Matrix4fc> supplier) {
 		super(name, updateFrequency, new Matrix4f(), supplier);
 	}
 
 	@Override
-	protected void setFrom(Matrix4f other) {
+	protected void setFrom(Matrix4fc other) {
 		((Matrix4f) this.cached).set(other);
 	}
 

src/main/java/net/coderbot/iris/uniforms/custom/cached/Int3VectorCachedUniform.java

@@ -4,23 +4,24 @@ import net.coderbot.iris.gl.uniform.UniformUpdateFrequency;
 import net.coderbot.iris.parsing.VectorType;
 import org.joml.Vector3i;
 import com.gtnewhorizons.angelica.glsm.GLStateManager;
+import org.joml.Vector3ic;
 
 import java.util.function.Supplier;
 
-public class Int3VectorCachedUniform extends VectorCachedUniform<Vector3i> {
+public class Int3VectorCachedUniform extends VectorCachedUniform<Vector3ic> {
 
-	public Int3VectorCachedUniform(String name, UniformUpdateFrequency updateFrequency, Supplier<Vector3i> supplier) {
+	public Int3VectorCachedUniform(String name, UniformUpdateFrequency updateFrequency, Supplier<Vector3ic> supplier) {
 		super(name, updateFrequency, new Vector3i(), supplier);
 	}
 
 	@Override
-	protected void setFrom(Vector3i other) {
-		this.cached.set(other);
+	protected void setFrom(Vector3ic other) {
+		((Vector3i)this.cached).set(other);
 	}
 
 	@Override
 	public void push(int location) {
-		GLStateManager.glUniform3i(location, this.cached.x, this.cached.y, this.cached.z);
+		GLStateManager.glUniform3i(location, this.cached.x(), this.cached.y(), this.cached.z());
 	}
 
 	@Override

src/mixin/java/com/gtnewhorizons/angelica/mixins/early/shaders/MixinEntityRenderer.java

@@ -7,6 +7,7 @@ import com.llamalad7.mixinextras.injector.wrapoperation.WrapOperation;
 import com.llamalad7.mixinextras.sugar.Share;
 import com.llamalad7.mixinextras.sugar.ref.LocalRef;
 import net.coderbot.iris.Iris;
+import net.coderbot.iris.compat.dh.DHCompat;
 import net.coderbot.iris.gl.program.Program;
 import net.coderbot.iris.pipeline.HandRenderer;
 import net.coderbot.iris.pipeline.WorldRenderingPhase;
@@ -35,6 +36,9 @@ public abstract class MixinEntityRenderer implements IResourceManagerReloadListe
 
     @Inject(at = @At(value = "INVOKE", target = "Lnet/minecraft/client/renderer/culling/ClippingHelperImpl;getInstance()Lnet/minecraft/client/renderer/culling/ClippingHelper;", shift = At.Shift.AFTER, ordinal = 0), method = "renderWorld(FJ)V")
     private void iris$beginRender(float partialTicks, long startTime, CallbackInfo ci, @Share("pipeline") LocalRef<WorldRenderingPipeline> pipeline) {
+        DHCompat.checkFrame();
+        Iris.tryLoadShaderpackWhenPossible();
+
         CapturedRenderingState.INSTANCE.setTickDelta(partialTicks);
         SystemTimeUniforms.COUNTER.beginFrame();
         SystemTimeUniforms.TIMER.beginFrame(System.nanoTime());