From 6aad156a32ab552bac8f3a24df0edf78bda98a8a Mon Sep 17 00:00:00 2001
From: James Seibel <jeseibel@gondtc.com>
Date: Tue, 24 Mar 2026 07:16:31 -0500
Subject: [PATCH] Fix Iris using the wrong far clip plane

https://github.com/IrisShaders/Iris/issues/2534
---
 .../distanthorizons/core/util/RenderUtil.java | 39 ++++++++++++++++---
 1 file changed, 33 insertions(+), 6 deletions(-)

diff --git a/core/src/main/java/com/seibel/distanthorizons/core/util/RenderUtil.java b/core/src/main/java/com/seibel/distanthorizons/core/util/RenderUtil.java
index bc9bc7799..30c22169d 100644
--- a/core/src/main/java/com/seibel/distanthorizons/core/util/RenderUtil.java
+++ b/core/src/main/java/com/seibel/distanthorizons/core/util/RenderUtil.java
@@ -19,12 +19,17 @@
 
 package com.seibel.distanthorizons.core.util;
 
+import com.seibel.distanthorizons.api.DhApi;
 import com.seibel.distanthorizons.api.objects.math.DhApiMat4f;
 import com.seibel.distanthorizons.core.api.internal.ClientApi;
 import com.seibel.distanthorizons.core.config.Config;
+import com.seibel.distanthorizons.core.dependencyInjection.ModAccessorInjector;
 import com.seibel.distanthorizons.core.dependencyInjection.SingletonInjector;
+import com.seibel.distanthorizons.core.logging.DhLogger;
+import com.seibel.distanthorizons.core.logging.DhLoggerBuilder;
 import com.seibel.distanthorizons.core.wrapperInterfaces.minecraft.IMinecraftClientWrapper;
 import com.seibel.distanthorizons.core.wrapperInterfaces.minecraft.IMinecraftRenderWrapper;
+import com.seibel.distanthorizons.core.wrapperInterfaces.modAccessor.IIrisAccessor;
 import com.seibel.distanthorizons.core.wrapperInterfaces.world.IClientLevelWrapper;
 import com.seibel.distanthorizons.coreapi.util.MathUtil;
 import com.seibel.distanthorizons.core.util.math.Mat4f;
@@ -35,8 +40,11 @@ import com.seibel.distanthorizons.core.util.math.Mat4f;
  */
 public class RenderUtil
 {
+	private static final DhLogger LOGGER = new DhLoggerBuilder().maxCountPerSecond(1).build();
+	
 	private static final IMinecraftClientWrapper MC = SingletonInjector.INSTANCE.get(IMinecraftClientWrapper.class);
 	private static final IMinecraftRenderWrapper MC_RENDER = SingletonInjector.INSTANCE.get(IMinecraftRenderWrapper.class);
+	private static final IIrisAccessor IRIS_ACCESSOR = ModAccessorInjector.INSTANCE.get(IIrisAccessor.class);
 	
 	/** 
 	 * all speeds are measured in blocks per second 
@@ -79,7 +87,7 @@ public class RenderUtil
 			nearClipDist = Math.min(nearClipDist, 7.5f);
 		}
 		
-		float farClipDist = (float) RenderUtil.getFarClipPlaneDistanceInBlocks();
+		float farClipDist = RenderUtil.getFarClipPlaneDistanceInBlocks();
 		
 		// Create a copy of the current matrix, so it won't be modified.
 		Mat4f lodProj = new Mat4f(mcProjMat);
@@ -245,12 +253,31 @@ public class RenderUtil
 	
 	//region
 	
-	public static int getFarClipPlaneDistanceInBlocks()
+	public static float getFarClipPlaneDistanceInBlocks()
 	{
-		int lodChunkDist = Config.Client.Advanced.Graphics.Quality.lodChunkRenderDistanceRadius.get();
-		int lodBlockDist = lodChunkDist * LodUtil.CHUNK_WIDTH;
-		// * 2 to prevent clipping when high above the world
-		return (lodBlockDist + LodUtil.REGION_WIDTH) * 2;
+		if (IRIS_ACCESSOR != null)
+		{
+			// Iris doesn't use the far clip plane DH generates, instead
+			// they use a manually generated one, which causes problems.
+			// This is a hack so DH's far clip plane matches up with what Iris thinks it is,
+			// fixing projection/depth mapping.
+			// https://github.com/IrisShaders/Iris/issues/2534
+			
+			int lodChunkDist = DhApi.Delayed.configs.graphics().chunkRenderDistance().getValue();
+			int lodBlockDist = lodChunkDist * 16; /* 16 = chunk width in blocks */
+			// sqrt 2 to prevent the corners from being cut off
+			return (float) ((lodBlockDist + 512 /* 512 = region width in blocks */) * Math.sqrt(2));
+		}
+		else
+		{
+			// Current DH logic
+			// uses a farther depth to help when far above the world
+			
+			int lodChunkDist = Config.Client.Advanced.Graphics.Quality.lodChunkRenderDistanceRadius.get();
+			int lodBlockDist = lodChunkDist * LodUtil.CHUNK_WIDTH;
+			// * 2 to prevent clipping when high above the world
+			return (lodBlockDist + LodUtil.REGION_WIDTH) * 2;
+		}
 	}
 	
 	//endregion