From cb049f5ace4bd789a58f563c9d78089dcf4e5ab1 Mon Sep 17 00:00:00 2001
From: IMS212 <ims@irisshaders.dev>
Date: Fri, 23 Aug 2024 17:28:11 -0700
Subject: [PATCH] Use vertex buffer offsets instead of pointers

---
 .../iris/mixin/MixinByteBufferBuilder.java    | 17 ++++++++++
 .../mixin/vertices/MixinBufferBuilder.java    | 33 ++++++++++++-------
 .../vertices/BufferBuilderPolygonView.java    | 18 +++++-----
 .../iris/vertices/MojangBufferAccessor.java   |  5 +++
 common/src/main/resources/mixins.iris.json    |  1 +
 5 files changed, 54 insertions(+), 20 deletions(-)
 create mode 100644 common/src/main/java/net/irisshaders/iris/mixin/MixinByteBufferBuilder.java
 create mode 100644 common/src/main/java/net/irisshaders/iris/vertices/MojangBufferAccessor.java

diff --git a/common/src/main/java/net/irisshaders/iris/mixin/MixinByteBufferBuilder.java b/common/src/main/java/net/irisshaders/iris/mixin/MixinByteBufferBuilder.java
new file mode 100644
index 0000000000..25b8039664
--- /dev/null
+++ b/common/src/main/java/net/irisshaders/iris/mixin/MixinByteBufferBuilder.java
@@ -0,0 +1,17 @@
+package net.irisshaders.iris.mixin;
+
+import com.mojang.blaze3d.vertex.ByteBufferBuilder;
+import net.irisshaders.iris.vertices.MojangBufferAccessor;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+
+@Mixin(ByteBufferBuilder.class)
+public class MixinByteBufferBuilder implements MojangBufferAccessor {
+	@Shadow
+	long pointer;
+
+	@Override
+	public long getPointer() {
+		return this.pointer;
+	}
+}
diff --git a/common/src/main/java/net/irisshaders/iris/mixin/vertices/MixinBufferBuilder.java b/common/src/main/java/net/irisshaders/iris/mixin/vertices/MixinBufferBuilder.java
index 980984b94a..bdbd7aa1df 100644
--- a/common/src/main/java/net/irisshaders/iris/mixin/vertices/MixinBufferBuilder.java
+++ b/common/src/main/java/net/irisshaders/iris/mixin/vertices/MixinBufferBuilder.java
@@ -1,6 +1,7 @@
 package net.irisshaders.iris.mixin.vertices;
 
 import com.mojang.blaze3d.vertex.BufferBuilder;
+import com.mojang.blaze3d.vertex.ByteBufferBuilder;
 import com.mojang.blaze3d.vertex.DefaultVertexFormat;
 import com.mojang.blaze3d.vertex.VertexConsumer;
 import com.mojang.blaze3d.vertex.VertexFormat;
@@ -12,6 +13,7 @@
 import net.irisshaders.iris.vertices.ExtendedDataHelper;
 import net.irisshaders.iris.vertices.ImmediateState;
 import net.irisshaders.iris.vertices.IrisVertexFormats;
+import net.irisshaders.iris.vertices.MojangBufferAccessor;
 import net.irisshaders.iris.vertices.NormI8;
 import net.irisshaders.iris.vertices.NormalHelper;
 import org.joml.Vector3f;
@@ -76,7 +78,7 @@ public abstract class MixinBufferBuilder implements VertexConsumer, BlockSensiti
 	@Unique
 	private int currentLocalPosZ;
 	@Unique
-	private final long[] vertexPointers = new long[4];
+	private final long[] vertexOffsets = new long[4];
 
 	@Shadow
 	public abstract VertexConsumer setNormal(float f, float g, float h);
@@ -84,6 +86,10 @@ public abstract class MixinBufferBuilder implements VertexConsumer, BlockSensiti
 	@Shadow
 	protected abstract long beginElement(VertexFormatElement vertexFormatElement);
 
+	@Shadow
+	@Final
+	private ByteBufferBuilder buffer;
+
 	@ModifyVariable(method = "<init>", at = @At(value = "FIELD", target = "Lcom/mojang/blaze3d/vertex/VertexFormatElement;POSITION:Lcom/mojang/blaze3d/vertex/VertexFormatElement;", ordinal = 0), argsOnly = true)
 	private VertexFormat iris$extendFormat(VertexFormat format) {
         boolean iris$isTerrain = false;
@@ -170,7 +176,7 @@ private void injectMidBlock(float x, float y, float z, CallbackInfoReturnable<Ve
 			return;
 		}
 
-		vertexPointers[iris$vertexCount] = vertexPointer;
+		vertexOffsets[iris$vertexCount] = vertexPointer - ((MojangBufferAccessor) buffer).getPointer();
 
 		iris$vertexCount++;
 
@@ -203,7 +209,7 @@ private void fillExtendedData(int vertexAmount) {
 
 		int stride = format.getVertexSize();
 
-		polygon.setup(vertexPointers, stride, vertexAmount);
+		polygon.setup(((MojangBufferAccessor) buffer).getPointer(), vertexOffsets, stride, vertexAmount);
 
 		float midU = 0;
 		float midV = 0;
@@ -223,13 +229,14 @@ private void fillExtendedData(int vertexAmount) {
 			// NormalHelper.computeFaceNormalTri(normal, polygon);	// Removed to enable smooth shaded triangles. Mods rendering triangles with bad normals need to recalculate their normals manually or otherwise shading might be inconsistent.
 
 			for (int vertex = 0; vertex < vertexAmount; vertex++) {
-				int vertexNormal = MemoryUtil.memGetInt(vertexPointers[vertex] + normalOffset); // retrieve per-vertex normal
+				long newPointer = ((MojangBufferAccessor) buffer).getPointer() + vertexOffsets[vertex];
+				int vertexNormal = MemoryUtil.memGetInt(newPointer + normalOffset); // retrieve per-vertex normal
 
 				int tangent = NormalHelper.computeTangentSmooth(NormI8.unpackX(vertexNormal), NormI8.unpackY(vertexNormal), NormI8.unpackZ(vertexNormal), polygon);
 
-				MemoryUtil.memPutFloat(vertexPointers[vertex] + midTexOffset, midU);
-				MemoryUtil.memPutFloat(vertexPointers[vertex] + midTexOffset + 4, midV);
-				MemoryUtil.memPutInt(vertexPointers[vertex] + tangentOffset, tangent);
+				MemoryUtil.memPutFloat(newPointer + midTexOffset, midU);
+				MemoryUtil.memPutFloat(newPointer + midTexOffset + 4, midV);
+				MemoryUtil.memPutInt(newPointer + tangentOffset, tangent);
 			}
 		} else {
 			NormalHelper.computeFaceNormal(normal, polygon);
@@ -237,13 +244,15 @@ private void fillExtendedData(int vertexAmount) {
 			int tangent = NormalHelper.computeTangent(normal.x, normal.y, normal.z, polygon);
 
 			for (int vertex = 0; vertex < vertexAmount; vertex++) {
-				MemoryUtil.memPutFloat(vertexPointers[vertex] + midTexOffset, midU);
-				MemoryUtil.memPutFloat(vertexPointers[vertex] + midTexOffset + 4, midV);
-				MemoryUtil.memPutInt(vertexPointers[vertex] + normalOffset, packedNormal);
-				MemoryUtil.memPutInt(vertexPointers[vertex] + tangentOffset, tangent);
+				long newPointer = ((MojangBufferAccessor) buffer).getPointer() + vertexOffsets[vertex];
+
+				MemoryUtil.memPutFloat(newPointer + midTexOffset, midU);
+				MemoryUtil.memPutFloat(newPointer + midTexOffset + 4, midV);
+				MemoryUtil.memPutInt(newPointer + normalOffset, packedNormal);
+				MemoryUtil.memPutInt(newPointer + tangentOffset, tangent);
 			}
 		}
 
-		Arrays.fill(vertexPointers, 0);
+		Arrays.fill(vertexOffsets, 0);
 	}
 }
diff --git a/common/src/main/java/net/irisshaders/iris/vertices/BufferBuilderPolygonView.java b/common/src/main/java/net/irisshaders/iris/vertices/BufferBuilderPolygonView.java
index 19e30e5be1..d0aafb5365 100644
--- a/common/src/main/java/net/irisshaders/iris/vertices/BufferBuilderPolygonView.java
+++ b/common/src/main/java/net/irisshaders/iris/vertices/BufferBuilderPolygonView.java
@@ -4,34 +4,36 @@
 import org.lwjgl.system.MemoryUtil;
 
 public class BufferBuilderPolygonView implements QuadView {
-	private long[] writePointers;
+	private long[] writeOffsets;
+	private long pointer;
 
-	public void setup(long[] writePointers, int stride, int vertexAmount) {
-		this.writePointers = writePointers;
+	public void setup(long pointer, long[] writeOffsets, int stride, int vertexAmount) {
+		this.pointer = pointer;
+		this.writeOffsets = writeOffsets;
 	}
 
 	@Override
 	public float x(int index) {
-		return MemoryUtil.memGetFloat(writePointers[index]);
+		return MemoryUtil.memGetFloat(pointer + writeOffsets[index]);
 	}
 
 	@Override
 	public float y(int index) {
-		return MemoryUtil.memGetFloat(writePointers[index] + 4);
+		return MemoryUtil.memGetFloat(pointer + writeOffsets[index] + 4);
 	}
 
 	@Override
 	public float z(int index) {
-		return MemoryUtil.memGetFloat(writePointers[index] + 8);
+		return MemoryUtil.memGetFloat(pointer + writeOffsets[index] + 8);
 	}
 
 	@Override
 	public float u(int index) {
-		return MemoryUtil.memGetFloat(writePointers[index] + 16);
+		return MemoryUtil.memGetFloat(pointer + writeOffsets[index] + 16);
 	}
 
 	@Override
 	public float v(int index) {
-		return MemoryUtil.memGetFloat(writePointers[index] + 20);
+		return MemoryUtil.memGetFloat(pointer + writeOffsets[index] + 20);
 	}
 }
diff --git a/common/src/main/java/net/irisshaders/iris/vertices/MojangBufferAccessor.java b/common/src/main/java/net/irisshaders/iris/vertices/MojangBufferAccessor.java
new file mode 100644
index 0000000000..80797469b4
--- /dev/null
+++ b/common/src/main/java/net/irisshaders/iris/vertices/MojangBufferAccessor.java
@@ -0,0 +1,5 @@
+package net.irisshaders.iris.vertices;
+
+public interface MojangBufferAccessor {
+	long getPointer();
+}
diff --git a/common/src/main/resources/mixins.iris.json b/common/src/main/resources/mixins.iris.json
index adeba4c9e9..9cf26e2834 100644
--- a/common/src/main/resources/mixins.iris.json
+++ b/common/src/main/resources/mixins.iris.json
@@ -15,6 +15,7 @@
     "MixinBiomes",
     "MixinBlockStateBehavior",
     "MixinBooleanState",
+    "MixinByteBufferBuilder",
     "MixinChainedJsonException",
     "MixinClientLanguage",
     "MixinClientPacketListener",