From 85b134b7be0411fcda366ee0ce6a969cdc978b7d Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Tue, 4 Nov 2025 13:27:21 +0100
Subject: [PATCH] Add improved Global SDF quality and precision of
 rasterization

---
 Content/Editor/Primitives/Cube.flax               | 4 ++--
 Source/Engine/Tools/ModelTool/ModelTool.cpp       | 2 ++
 Source/Shaders/SDF.shader                         | 2 ++
 Source/Shaders/ThirdParty/TressFX/TressFXSDF.hlsl | 8 ++++++++
 4 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/Content/Editor/Primitives/Cube.flax b/Content/Editor/Primitives/Cube.flax
index 6328a7bbc..b12f75e05 100644
--- a/Content/Editor/Primitives/Cube.flax
+++ b/Content/Editor/Primitives/Cube.flax
@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:b5a18bf58e0b93c8bba9459fd77a92898f0fae373b58d3acbcb9e36f66c89cd7
-size 23537
+oid sha256:8e8d210a74ae373793eaee1ddab1372a6a50a000c489f97b2258a09cd93cc2d0
+size 5031
diff --git a/Source/Engine/Tools/ModelTool/ModelTool.cpp b/Source/Engine/Tools/ModelTool/ModelTool.cpp
index 0ae1e0639..78a3fe515 100644
--- a/Source/Engine/Tools/ModelTool/ModelTool.cpp
+++ b/Source/Engine/Tools/ModelTool/ModelTool.cpp
@@ -366,9 +366,11 @@ bool ModelTool::GenerateModelSDF(Model* inputModel, const ModelData* modelData,
         return true;
     ModelBase::SDFData sdf;
     sdf.WorldUnitsPerVoxel = METERS_TO_UNITS(0.1f) / Math::Max(resolutionScale, 0.0001f); // 1 voxel per 10 centimeters
+#if 0
     const float boundsMargin = sdf.WorldUnitsPerVoxel * 0.5f; // Add half-texel margin around the mesh
     bounds.Minimum -= boundsMargin;
     bounds.Maximum += boundsMargin;
+#endif
     const Float3 size = bounds.GetSize();
     Int3 resolution(Float3::Ceil(Float3::Clamp(size / sdf.WorldUnitsPerVoxel, 4, 256)));
     Float3 uvwToLocalMul = size;
diff --git a/Source/Shaders/SDF.shader b/Source/Shaders/SDF.shader
index ba2626ff9..2239e2dbe 100644
--- a/Source/Shaders/SDF.shader
+++ b/Source/Shaders/SDF.shader
@@ -142,8 +142,10 @@ void CS_RasterizeTriangle(uint3 DispatchThreadId : SV_DispatchThreadID)
                 int voxelIndex = GetVoxelIndex(voxelCoord);
                 float3 voxelPos = GetVoxelPos(voxelCoord);
                 float distance = SignedDistancePointToTriangle(voxelPos, v0, v1, v2);
+#if 0
                 if (distance < -10.0f) // TODO: find a better way to reject negative distance from degenerate triangles that break SDF shape
                     distance = abs(distance);
+#endif
                 InterlockedMin(SDF[voxelIndex], FloatFlip3(distance));
             }
         }
diff --git a/Source/Shaders/ThirdParty/TressFX/TressFXSDF.hlsl b/Source/Shaders/ThirdParty/TressFX/TressFXSDF.hlsl
index 13c28f16d..7128ba9ca 100644
--- a/Source/Shaders/ThirdParty/TressFX/TressFXSDF.hlsl
+++ b/Source/Shaders/ThirdParty/TressFX/TressFXSDF.hlsl
@@ -52,6 +52,14 @@ uint IFloatFlip3(uint f2)
 
 float DistancePointToEdge(float3 p, float3 x0, float3 x1, out float3 n)
 {
+    // Hack to swap to ensure the order is correct (.x only for simplicity)
+	if (x0.x > x1.x)
+	{
+		float3 temp = x0;
+		x0 = x1;
+		x1 = temp;
+	}
+
     float3 x10 = x1 - x0;
 
     float t = dot(x1 - p, x10) / dot(x10, x10);