[2021.2] Fixing a shadow artefact on Terrain Detail objects

com.unity.render-pipelines.universal/CHANGELOG.md

@@ -104,6 +104,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed depth of field pass usage on unsupported devices. [case 1327076](https://issuetracker.unity3d.com/issues/adreno-3xx-nothing-is-rendered-when-post-processing-is-enabled)
 - Fixed an issue with Shader Graph Lit shaders where the normalized view direction produced incorrect lighting. [1332804]
 - Fixed return values from GetStereoProjectionMatrix() and SetStereoViewMatrix(). [case 1312813](https://issuetracker.unity3d.com/issues/xr-urp-begincamerarender-method-is-lagging-behind-when-using-urp)
+- Fixed an issue where shadow artefacts appeared between cascades on Terrain Detail objects.
 
 ### Changed
 - Change Asset/Create/Shader/Universal Render Pipeline/Lit Shader Graph to Asset/Create/Shader Graph/URP/Lit Shader Graph

com.unity.render-pipelines.universal/Shaders/Terrain/TerrainDetailLitPasses.hlsl

@@ -19,13 +19,11 @@ struct Varyings
     DECLARE_LIGHTMAP_OR_SH(staticLightmapUV, vertexSH, 1);
     half4   Color           : TEXCOORD2; // Vertex Color
     half4   LightingFog     : TEXCOORD3; // Vertex Lighting, Fog Factor
-    #if defined(MAIN_LIGHT_CALCULATE_SHADOWS)
+    #if defined(REQUIRES_VERTEX_SHADOW_COORD_INTERPOLATOR)
     float4  ShadowCoords    : TEXCOORD4; // Shadow UVs
     #endif
     half4   NormalWS        : TEXCOORD5;
-    #if defined(DEBUG_DISPLAY)
-    float3 positionWS       : TEXCOORD6;
-    #endif
+    float3  PositionWS      : TEXCOORD6;
     float4  PositionCS      : SV_POSITION; // Clip Position
 
     UNITY_VERTEX_INPUT_INSTANCE_ID
@@ -38,11 +36,15 @@ void InitializeInputData(Varyings input, out InputData inputData)
 
     inputData.normalWS = half3(0, 1, 0);
     inputData.viewDirectionWS = half3(0, 0, 1);
-    #if defined(MAIN_LIGHT_CALCULATE_SHADOWS)
-    inputData.shadowCoord = input.ShadowCoords;
+
+    #if defined(REQUIRES_VERTEX_SHADOW_COORD_INTERPOLATOR)
+        inputData.shadowCoord = IN.shadowCoord;
+    #elif defined(MAIN_LIGHT_CALCULATE_SHADOWS)
+        inputData.shadowCoord = TransformWorldToShadowCoord(input.PositionWS);
     #else
-    inputData.shadowCoord = float4(0, 0, 0, 0);
+        inputData.shadowCoord = float4(0, 0, 0, 0);
     #endif
+
     inputData.fogCoord = input.LightingFog.a;
     inputData.vertexLighting = input.LightingFog.rgb;
     inputData.bakedGI = SAMPLE_GI(input.staticLightmapUV, input.vertexSH, input.NormalWS.xyz);
@@ -59,11 +61,9 @@ void InitializeInputData(Varyings input, out InputData inputData)
     inputData.tangentToWorld;
     #endif
 
+    inputData.positionWS = input.PositionWS;
     #if defined(DEBUG_DISPLAY)
-    inputData.positionWS = input.positionWS;
     inputData.uv = input.UV01;
-    #else
-    inputData.positionWS = float3(0, 0, 0);
     #endif
 }
 
@@ -134,8 +134,8 @@ Varyings TerrainLitVertex(Attributes input)
     output.PositionCS = vertexInput.positionCS;
 
     // Shadow Coords
-    #if defined(MAIN_LIGHT_CALCULATE_SHADOWS)
-    output.ShadowCoords = GetShadowCoord(vertexInput);
+    #if defined(REQUIRES_VERTEX_SHADOW_COORD_INTERPOLATOR)
+        output.ShadowCoords = GetShadowCoord(vertexInput);
     #endif
 
     // Vertex Lighting
@@ -169,10 +169,7 @@ Varyings TerrainLitVertex(Attributes input)
     output.LightingFog.w = ComputeFogFactor(output.PositionCS.z);
 
     output.NormalWS.xyz = NormalWS;
-
-    #if defined(DEBUG_DISPLAY)
-    output.positionWS = vertexInput.positionWS;
-    #endif
+    output.PositionWS = vertexInput.positionWS;
 
     return output;
 }