Add gaussian splat asset caching groundwork

engine/assets/builtin/shaders/gaussian-splat-composite.shader

@@ -0,0 +1,46 @@
+Shader "Builtin Gaussian Splat Composite"
+{
+    SubShader
+    {
+        Pass
+        {
+            Name "GaussianComposite"
+            Tags { "LightMode" = "GaussianComposite" }
+            Cull Off
+            ZWrite Off
+            ZTest Always
+            Blend One OneMinusSrcAlpha
+            HLSLPROGRAM
+            #pragma target 4.5
+            #pragma vertex MainVS
+            #pragma fragment MainPS
+
+            Texture2D GaussianSplatAccumulationTexture;
+
+            struct VSOutput
+            {
+                float4 position : SV_POSITION;
+            };
+
+            VSOutput MainVS(uint vertexId : SV_VertexID)
+            {
+                const float2 positions[3] = {
+                    float2(-1.0f, -1.0f),
+                    float2(-1.0f,  3.0f),
+                    float2( 3.0f, -1.0f)
+                };
+
+                VSOutput output;
+                output.position = float4(positions[vertexId], 1.0f, 1.0f);
+                return output;
+            }
+
+            float4 MainPS(VSOutput input) : SV_TARGET
+            {
+                const int2 pixelCoord = int2(input.position.xy);
+                return GaussianSplatAccumulationTexture.Load(int3(pixelCoord, 0));
+            }
+            ENDHLSL
+        }
+    }
+}

engine/assets/builtin/shaders/gaussian-splat-utilities.shader

@@ -229,21 +229,21 @@ Shader "Builtin Gaussian Splat Utilities"
     }
 
     float3 CalcCovariance2D(
-        float3 viewPosition,
+        float3 localPosition,
         float3 covariance3D0,
         float3 covariance3D1,
-        float4x4 viewMatrix,
+        float4x4 modelViewMatrix,
         float4x4 projectionMatrix,
         float2 screenSize)
     {
+        const float3 viewPosition = mul(modelViewMatrix, float4(localPosition, 1.0)).xyz;
         if (abs(viewPosition.z) <= 1.0e-5)
         {
             return float3(0.3, 0.0, 0.3);
         }
 
-        const float aspect = projectionMatrix[0][0] / projectionMatrix[1][1];
         const float tanFovX = rcp(projectionMatrix[0][0]);
-        const float tanFovY = rcp(projectionMatrix[1][1] * aspect);
+        const float tanFovY = rcp(projectionMatrix[1][1]);
         const float limitX = 1.3 * tanFovX;
         const float limitY = 1.3 * tanFovY;
 
@@ -264,7 +264,7 @@ Shader "Builtin Gaussian Splat Utilities"
             0.0,
             0.0,
             0.0);
-        const float3x3 worldToView = (float3x3)viewMatrix;
+        const float3x3 worldToView = (float3x3)modelViewMatrix;
         const float3x3 transform = mul(jacobian, worldToView);
         const float3x3 covariance3D = float3x3(
             covariance3D0.x, covariance3D0.y, covariance3D0.z,
@@ -284,7 +284,7 @@ Shader "Builtin Gaussian Splat Utilities"
         const float offDiagonal = covariance2D.y;
         const float mid = 0.5 * (diagonal0 + diagonal1);
         const float radius = length(float2((diagonal0 - diagonal1) * 0.5, offDiagonal));
-        const float lambda0 = max(mid + radius, 0.1);
+        const float lambda0 = mid + radius;
         const float lambda1 = max(mid - radius, 0.1);
 
         float2 basis = normalize(float2(offDiagonal, lambda0 - diagonal0));
@@ -425,22 +425,22 @@ Shader "Builtin Gaussian Splat Utilities"
                 GaussianSplatSortDistances[index] = FloatToSortableUint(viewCenter.z);
 
                 const float4 clipCenter = mul(gProjectionMatrix, float4(viewCenter, 1.0));
-                if (clipCenter.w > 0.0)
+                const float nearClip = max(gCameraWorldPos.w, 1.0e-4);
+                if (clipCenter.w > 0.0 && viewCenter.z > nearClip)
                 {
-                    const float3x3 modelLinear = (float3x3)gModelMatrix;
+                    const float4x4 modelViewMatrix = mul(gViewMatrix, gModelMatrix);
                     const float3x3 rotationScaleMatrix =
                         CalcMatrixFromRotationScale(otherData.rotation, otherData.scaleReserved.xyz);
-                    const float3x3 worldRotationScale = mul(modelLinear, rotationScaleMatrix);
 
                     float3 covariance3D0 = 0.0;
                     float3 covariance3D1 = 0.0;
-                    CalcCovariance3D(worldRotationScale, covariance3D0, covariance3D1);
+                    CalcCovariance3D(rotationScaleMatrix, covariance3D0, covariance3D1);
 
                     const float3 covariance2D = CalcCovariance2D(
-                        viewCenter,
+                        localCenter,
                         covariance3D0,
                         covariance3D1,
-                        gViewMatrix,
+                        modelViewMatrix,
                         gProjectionMatrix,
                         gScreenParams.xy);
 

engine/assets/builtin/shaders/gaussian-splat.shader

@@ -4,6 +4,7 @@ Shader "Builtin Gaussian Splat"
     {
         _PointScale ("Point Scale", Float) = 1.0
         _OpacityScale ("Opacity Scale", Float) = 1.0
+        _DebugViewMode ("Debug View Mode", Float) = 0.0
     }
     HLSLINCLUDE
     cbuffer PerObjectConstants
@@ -23,6 +24,7 @@ Shader "Builtin Gaussian Splat"
     {
         float4 gPointScaleParams;
         float4 gOpacityScaleParams;
+        float4 gDebugViewModeParams;
     };
 
     struct GaussianSplatViewData
@@ -91,8 +93,14 @@ Shader "Builtin Gaussian Splat"
             discard;
         }
 
-        return float4(input.colorOpacity.rgb, alpha);
+        if (gDebugViewModeParams.x >= 0.5)
+        {
+            return float4(alpha, alpha, alpha, alpha);
+        }
+
+        return float4(input.colorOpacity.rgb * alpha, alpha);
     }
+
     ENDHLSL
 
     SubShader
@@ -105,12 +113,13 @@ Shader "Builtin Gaussian Splat"
             Cull Off
             ZWrite Off
             ZTest LEqual
-            Blend SrcAlpha OneMinusSrcAlpha
+            Blend OneMinusDstAlpha One
             HLSLPROGRAM
             #pragma target 4.5
             #pragma vertex MainVS
             #pragma fragment MainPS
             ENDHLSL
         }
+
     }
 }