[Port] [6000.0] URP: Fix screen-space decals in Deferred

Author: Mikkel Simonsen

Packages/com.unity.render-pipelines.universal/Editor/Decal/DecalPass.template

@@ -64,8 +64,8 @@ Pass
     #endif
     #if _RENDER_PASS_ENABLED
     #define GBUFFER3 0
+    FRAMEBUFFER_INPUT_X_FLOAT(GBUFFER3);
     #define GBUFFER4 1
-    FRAMEBUFFER_INPUT_X_HALF(GBUFFER3);
     FRAMEBUFFER_INPUT_X_HALF(GBUFFER4);
     #endif
     // Includes

Packages/com.unity.render-pipelines.universal/Editor/ShaderGraph/Includes/ShaderPassDecal.hlsl

@@ -240,15 +240,21 @@ void Frag(PackedVaryings packedInput,
 #endif
 
 #if defined(DECAL_RECONSTRUCT_NORMAL)
-    #if defined(_DECAL_NORMAL_BLEND_HIGH)
+    #if defined(_RENDER_PASS_ENABLED)
+        half3 normalWS = half3(ReconstructNormalDerivative(input.positionCS.xy, LOAD_FRAMEBUFFER_X_INPUT(GBUFFER3, positionCS.xy).x));
+    #elif defined(_DECAL_NORMAL_BLEND_HIGH)
         half3 normalWS = half3(ReconstructNormalTap9(positionCS.xy));
     #elif defined(_DECAL_NORMAL_BLEND_MEDIUM)
         half3 normalWS = half3(ReconstructNormalTap5(positionCS.xy));
     #else
         half3 normalWS = half3(ReconstructNormalDerivative(input.positionCS.xy));
     #endif
 #elif defined(DECAL_LOAD_NORMAL)
-    half3 normalWS = half3(LoadSceneNormals(positionCS.xy));
+    #if defined(_RENDER_PASS_ENABLED)
+    half3 normalWS = normalize(LOAD_FRAMEBUFFER_X_INPUT(GBUFFER2, positionCS.xy).rgb);
+    #else
+    half3 normalWS = normalize(LoadSceneNormals(positionCS.xy).rgb);
+    #endif
 #endif
 
     float2 positionSS = FoveatedRemapNonUniformToLinearCS(input.positionCS.xy) * _ScreenSize.zw;

Packages/com.unity.render-pipelines.universal/Editor/VFXGraph/Shaders/Templates/URPDecal/PassGBuffer.template

@@ -44,8 +44,8 @@
 
     #if _RENDER_PASS_ENABLED
     #define GBUFFER3 0
+    FRAMEBUFFER_INPUT_X_FLOAT(GBUFFER3);
     #define GBUFFER4 1
-    FRAMEBUFFER_INPUT_X_HALF(GBUFFER3);
     FRAMEBUFFER_INPUT_X_HALF(GBUFFER4);
     #endif
 

Packages/com.unity.render-pipelines.universal/ShaderLibrary/NormalReconstruction.hlsl

@@ -20,6 +20,26 @@ float GetRawDepth(float2 uv)
 // https://github.com/keijiro/DepthInverseProjection
 // constructs view space ray at the far clip plane from the screen uv
 // then multiplies that ray by the linear 01 depth
+float3 ViewSpacePosAtScreenUV(float2 uv, float deviceDepth)
+{
+    float3 viewSpaceRay = mul(_NormalReconstructionMatrix[unity_eyeIndex], float4(uv * 2.0 - 1.0, 1.0, 1.0) * _ProjectionParams.z).xyz;
+    return viewSpaceRay * Linear01Depth(deviceDepth, _ZBufferParams);
+}
+
+float3 ViewSpacePosAtPixelPosition(float2 positionSS, float deviceDepth)
+{
+    float2 uv = positionSS * _ScreenSize.zw;
+    return ViewSpacePosAtScreenUV(uv, deviceDepth);
+}
+
+half3 ReconstructNormalDerivative(float2 positionSS, float deviceDepth)
+{
+    float3 viewSpacePos = ViewSpacePosAtPixelPosition(positionSS, deviceDepth);
+    float3 hDeriv = ddy(viewSpacePos);
+    float3 vDeriv = ddx(viewSpacePos);
+    return half3(SafeNormalize(cross(hDeriv, vDeriv)));
+}
+
 float3 ViewSpacePosAtScreenUV(float2 uv)
 {
     float3 viewSpaceRay = mul(_NormalReconstructionMatrix[unity_eyeIndex], float4(uv * 2.0 - 1.0, 1.0, 1.0) * _ProjectionParams.z).xyz;