From 60e33ec044c999c5b4ee7015860175d40519e901 Mon Sep 17 00:00:00 2001
From: JellySquid <jellysquid@pm.me>
Date: Sat, 18 Jan 2025 12:45:58 -0600
Subject: [PATCH] Use 8 bits of sub-texel precision and fix off-by-one error
---
.../chunk/shader/DefaultShaderInterface.java | 28 +++++++------------
.../format/impl/CompactChunkVertex.java | 4 +--
2 files changed, 12 insertions(+), 20 deletions(-)
diff --git a/common/src/main/java/net/caffeinemc/mods/sodium/client/render/chunk/shader/DefaultShaderInterface.java b/common/src/main/java/net/caffeinemc/mods/sodium/client/render/chunk/shader/DefaultShaderInterface.java
index 5d0bda6be3..f2cb18fcb6 100644
--- a/common/src/main/java/net/caffeinemc/mods/sodium/client/render/chunk/shader/DefaultShaderInterface.java
+++ b/common/src/main/java/net/caffeinemc/mods/sodium/client/render/chunk/shader/DefaultShaderInterface.java
@@ -5,6 +5,7 @@
import net.caffeinemc.mods.sodium.client.gl.shader.uniform.GlUniformFloat3v;
import net.caffeinemc.mods.sodium.client.gl.shader.uniform.GlUniformInt;
import net.caffeinemc.mods.sodium.client.gl.shader.uniform.GlUniformMatrix4f;
+import net.caffeinemc.mods.sodium.client.render.chunk.vertex.format.impl.CompactChunkVertex;
import net.caffeinemc.mods.sodium.client.util.TextureUtil;
import net.caffeinemc.mods.sodium.mixin.core.render.texture.TextureAtlasAccessor;
import net.minecraft.client.Minecraft;
@@ -20,22 +21,9 @@
*/
public class DefaultShaderInterface implements ChunkShaderInterface {
// Direct3D specifies at least 8 bits of sub-texel precision for texture fetches. OpenGL specifies at least
- // 4 bits of sub-texel precision. Most OpenGL-capable graphics are Direct3D-capable as well, so we could
+ // 4 bits of sub-texel precision. Most OpenGL-capable graphics are Direct3D-capable as well, so we can
// *probably* assume 8 bits of precision.
- //
- // However, in practice, this seems to be a complete mess. The rounding behavior for point-filtering seems to
- // be defined inconsistently and depends on the shader compiler and hardware implementation. Apple's GL-on-Metal
- // implementation is the worst of all of them, with a very large epsilon (1.0 / 32.0) being needed to cure
- // texture seams between blocks.
- //
- // Unless we implemented texture filtering in the shader ourselves (i.e. using texelFetch(..)), it is unlikely
- // we could avoid these issues. And that would not help much in the case of linear interpolation across
- // mip layers.
- //
- // So in other words, this constant is the lowest common denominator we found through evaluation on the target
- // hardware. It is rather pessimistic to accommodate for Apple's implementation, but does seem to reliably fix
- // texture seams.
- private static final int SUB_TEXEL_PRECISION_BITS = 5;
+ private static final int SUB_TEXEL_PRECISION_BITS = 8;
private final Map<ChunkShaderTextureSlot, GlUniformInt> uniformTextures;
@@ -71,10 +59,14 @@ public void setupState() {
.getTexture(TextureAtlas.LOCATION_BLOCKS);
// There is a limited amount of sub-texel precision when using hardware texture sampling. The mapped texture
- // area must be "shrunk" by at least one sub-texel to avoid bleed between textures in the atlas.
+ // area must be "shrunk" by at least one sub-texel to avoid bleed between textures in the atlas. And since we
+ // offset texture coordinates in the vertex format by one texel, we also need to undo that here.
+ double subTexelPrecision = (1 << SUB_TEXEL_PRECISION_BITS);
+ double subTexelOffset = 1.0f / CompactChunkVertex.TEXTURE_MAX_VALUE;
+
this.uniformTexCoordShrink.set(
- (1.0f / textureAtlas.getWidth()) / (1 << SUB_TEXEL_PRECISION_BITS),
- (1.0f / textureAtlas.getHeight()) / (1 << SUB_TEXEL_PRECISION_BITS)
+ (float) (subTexelOffset + ((1.0D / textureAtlas.getWidth()) / subTexelPrecision)),
+ (float) (subTexelOffset + ((1.0D / textureAtlas.getHeight()) / subTexelPrecision))
);
this.fogShader.setup();
diff --git a/common/src/main/java/net/caffeinemc/mods/sodium/client/render/chunk/vertex/format/impl/CompactChunkVertex.java b/common/src/main/java/net/caffeinemc/mods/sodium/client/render/chunk/vertex/format/impl/CompactChunkVertex.java
index 44c73a8719..410dc0a5c0 100644
--- a/common/src/main/java/net/caffeinemc/mods/sodium/client/render/chunk/vertex/format/impl/CompactChunkVertex.java
+++ b/common/src/main/java/net/caffeinemc/mods/sodium/client/render/chunk/vertex/format/impl/CompactChunkVertex.java
@@ -18,8 +18,8 @@ public class CompactChunkVertex implements ChunkVertexType {
.addElement(DefaultChunkMeshAttributes.LIGHT_MATERIAL_INDEX, ChunkShaderBindingPoints.ATTRIBUTE_LIGHT_MATERIAL_INDEX, 16)
.build();
- private static final int POSITION_MAX_VALUE = 1 << 20;
- private static final int TEXTURE_MAX_VALUE = 1 << 15;
+ public static final int POSITION_MAX_VALUE = 1 << 20;
+ public static final int TEXTURE_MAX_VALUE = 1 << 15;
private static final float MODEL_ORIGIN = 8.0f;
private static final float MODEL_RANGE = 32.0f;