From 66a31d4fa00cd96148cc3dae220a99b55bcca1f5 Mon Sep 17 00:00:00 2001
From: viethungle0503 <viethungitmi@gmail.com>
Date: Thu, 2 Jul 2026 10:17:31 +0700
Subject: [PATCH 1/2] Sanitize splat rgba when packing ExtSplats to match
 PackedSplats clamping

---
 src/shaders/splatDefines.glsl | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/shaders/splatDefines.glsl b/src/shaders/splatDefines.glsl
index 3f082ac0..a30e4ea7 100644
--- a/src/shaders/splatDefines.glsl
+++ b/src/shaders/splatDefines.glsl
@@ -309,6 +309,7 @@ void packSplatExtCov(
     out uvec4 packedData, out uvec4 packedData2,
     vec3 center, vec4 rgba, vec3 xxyyzz, vec3 xyxzyz
 ) {
+    rgba = mix(clamp(rgba, 0.0, 65504.0), vec4(0.0), isnan(rgba));
     packedData.x = floatBitsToUint(center.x);
     packedData.y = floatBitsToUint(center.y);
     packedData.z = floatBitsToUint(center.z);
@@ -357,6 +358,7 @@ void packSplatExt(
     out uvec4 packedData, out uvec4 packedData2,
     vec3 center, vec3 scales, vec4 quaternion, vec4 rgba
 ) {
+    rgba = mix(clamp(rgba, 0.0, 65504.0), vec4(0.0), isnan(rgba));
     packedData.x = floatBitsToUint(center.x);
     packedData.y = floatBitsToUint(center.y);
     packedData.z = floatBitsToUint(center.z);

From a1d97a9ac76bb20579e44c9c814ef2fbdb5695f9 Mon Sep 17 00:00:00 2001
From: viethungle0503 <viethungitmi@gmail.com>
Date: Thu, 2 Jul 2026 18:32:45 +0700
Subject: [PATCH 2/2] Move the clamp to splatVertex and only clamp RGB to
 positive

---
 src/shaders/splatDefines.glsl | 2 --
 src/shaders/splatVertex.glsl  | 4 ++++
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/shaders/splatDefines.glsl b/src/shaders/splatDefines.glsl
index a30e4ea7..3f082ac0 100644
--- a/src/shaders/splatDefines.glsl
+++ b/src/shaders/splatDefines.glsl
@@ -309,7 +309,6 @@ void packSplatExtCov(
     out uvec4 packedData, out uvec4 packedData2,
     vec3 center, vec4 rgba, vec3 xxyyzz, vec3 xyxzyz
 ) {
-    rgba = mix(clamp(rgba, 0.0, 65504.0), vec4(0.0), isnan(rgba));
     packedData.x = floatBitsToUint(center.x);
     packedData.y = floatBitsToUint(center.y);
     packedData.z = floatBitsToUint(center.z);
@@ -358,7 +357,6 @@ void packSplatExt(
     out uvec4 packedData, out uvec4 packedData2,
     vec3 center, vec3 scales, vec4 quaternion, vec4 rgba
 ) {
-    rgba = mix(clamp(rgba, 0.0, 65504.0), vec4(0.0), isnan(rgba));
     packedData.x = floatBitsToUint(center.x);
     packedData.y = floatBitsToUint(center.y);
     packedData.z = floatBitsToUint(center.z);
diff --git a/src/shaders/splatVertex.glsl b/src/shaders/splatVertex.glsl
index ffbf93a0..1ad7c1b6 100644
--- a/src/shaders/splatVertex.glsl
+++ b/src/shaders/splatVertex.glsl
@@ -103,6 +103,10 @@ void main() {
         }
     }
 
+    // Match the reference 3DGS rasterizer (graphdeco-inria/diff-gaussian-rasterization),
+    // which clamps the SH-evaluated color to positive
+    rgba.rgb = max(rgba.rgb, vec3(0.0));
+
     adjustedStdDev = maxStdDev;
     if (rgba.a > 1.0) {
         // Stretch 1..2 to 1..5