[Unity6][URP] Fixing shadow issues when using Deferred Rendering (UUM-39576, UUM-71595, UUM-71598)

This PR does the following:

* Fixes UUM-39576 where additional light shadows would flicker if they exceeded the platform max for additional lights.
* Fixes UUM-71595 where additional light shadows were incorrectly ordered resulting in "random" order on screen.
* Fixes UUM-71598 where disabled additional lights shadows in the URP Asset had no effect when using deferred.
* Small performance improvements by refactoring some things in the additional light shadow caster pass
  * Improved the ComputeShadowRequestHash() function by not retrieving the VisibleLight twice and having unnecessary if checks. Also made sure this code only runs in Editor and Development builds, which are the only places it's used.
  * Moved some checks, that were done for each light and each slice but were only needed per light
  * Reduced the size of various containers inside AdditoinalLightShadowCasterPass. From int to short or byte.

Author: ellioman

Packages/com.unity.render-pipelines.universal/Runtime/DeferredLights.cs

@@ -321,10 +321,7 @@ internal void SetupLights(CommandBuffer cmd, UniversalCameraData cameraData, Vec
                 out m_stencilVisLights,
                 out m_stencilVisLightOffsets,
                 ref lightData.visibleLights,
-                lightData.additionalLightsCount != 0 || lightData.mainLightIndex >= 0,
-                cameraData.camera.worldToCameraMatrix,
-                cameraData.camera.orthographic,
-                cameraData.camera.nearClipPlane
+                lightData.additionalLightsCount != 0 || lightData.mainLightIndex >= 0
             );
 
             {
@@ -727,10 +724,7 @@ void PrecomputeLights(
             out NativeArray<ushort> stencilVisLights,
             out NativeArray<ushort> stencilVisLightOffsets,
             ref NativeArray<VisibleLight> visibleLights,
-            bool hasAdditionalLights,
-            Matrix4x4 view,
-            bool isOrthographic,
-            float zNear)
+            bool hasAdditionalLights)
         {
             const int lightTypeCount = (int)LightType.Tube + 1;
 
@@ -807,21 +801,26 @@ void RenderStencilLights(RasterCommandBuffer cmd, UniversalLightData lightData,
             using (new ProfilingScope(cmd, m_ProfilingSamplerDeferredStencilPass))
             {
                 NativeArray<VisibleLight> visibleLights = lightData.visibleLights;
+                bool hasLightCookieManager = m_LightCookieManager != null;
+                bool hasAdditionalLightPass = m_AdditionalLightsShadowCasterPass != null;
 
                 if (HasStencilLightsOfType(LightType.Directional))
-                    RenderStencilDirectionalLights(cmd, stripShadowsOffVariants, lightData, shadowData, visibleLights, lightData.mainLightIndex);
+                    RenderStencilDirectionalLights(cmd, stripShadowsOffVariants, lightData, shadowData, visibleLights, hasAdditionalLightPass, hasLightCookieManager, lightData.mainLightIndex);
 
-                if (HasStencilLightsOfType(LightType.Point))
-                    RenderStencilPointLights(cmd, stripShadowsOffVariants, lightData, shadowData, visibleLights);
+                if (lightData.supportsAdditionalLights)
+                {
+                    if (HasStencilLightsOfType(LightType.Point))
+                        RenderStencilPointLights(cmd, stripShadowsOffVariants, lightData, shadowData, visibleLights, hasAdditionalLightPass, hasLightCookieManager);
 
-                if (HasStencilLightsOfType(LightType.Spot))
-                    RenderStencilSpotLights(cmd, stripShadowsOffVariants, lightData, shadowData, visibleLights);
+                    if (HasStencilLightsOfType(LightType.Spot))
+                        RenderStencilSpotLights(cmd, stripShadowsOffVariants, lightData, shadowData, visibleLights, hasAdditionalLightPass, hasLightCookieManager);
+                }
             }
 
             Profiler.EndSample();
         }
 
-        void RenderStencilDirectionalLights(RasterCommandBuffer cmd, bool stripShadowsOffVariants, UniversalLightData lightData, UniversalShadowData shadowData, NativeArray<VisibleLight> visibleLights, int mainLightIndex)
+        void RenderStencilDirectionalLights(RasterCommandBuffer cmd, bool stripShadowsOffVariants, UniversalLightData lightData, UniversalShadowData shadowData, NativeArray<VisibleLight> visibleLights, bool hasAdditionalLightPass, bool hasLightCookieManager, int mainLightIndex)
         {
             if (m_FullscreenMesh == null)
                 m_FullscreenMesh = CreateFullscreenMesh();
@@ -830,10 +829,8 @@ void RenderStencilDirectionalLights(RasterCommandBuffer cmd, bool stripShadowsOf
 
             // TODO bundle extra directional lights rendering by batches of 8.
             // Also separate shadow caster lights from non-shadow caster.
-            bool isFirstLight = true;
-            bool hasLightCookieManager = m_LightCookieManager != null;
-            bool hasAdditionalLightPass = m_AdditionalLightsShadowCasterPass != null;
             int lastLightCookieIndex = -1;
+            bool isFirstLight = true;
             bool lastLightCookieKeywordState = false;
             bool lastShadowsKeywordState = false;
             bool lastSoftShadowsKeywordState = false;
@@ -891,17 +888,15 @@ void RenderStencilDirectionalLights(RasterCommandBuffer cmd, bool stripShadowsOf
             cmd.SetKeyword(ShaderGlobalKeywords._DIRECTIONAL, false);
         }
 
-        void RenderStencilPointLights(RasterCommandBuffer cmd, bool stripShadowsOffVariants, UniversalLightData lightData, UniversalShadowData shadowData, NativeArray<VisibleLight> visibleLights)
+        void RenderStencilPointLights(RasterCommandBuffer cmd, bool stripShadowsOffVariants, UniversalLightData lightData, UniversalShadowData shadowData, NativeArray<VisibleLight> visibleLights, bool hasAdditionalLightPass, bool hasLightCookieManager)
         {
             if (m_SphereMesh == null)
                 m_SphereMesh = CreateSphereMesh();
 
             cmd.SetKeyword(ShaderGlobalKeywords._POINT, true);
 
-            bool isFirstLight = true;
-            bool hasLightCookieManager = m_LightCookieManager != null;
-            bool hasAdditionalLightPass = m_AdditionalLightsShadowCasterPass != null;
             int lastLightCookieIndex = -1;
+            bool isFirstLight = true;
             bool lastLightCookieKeywordState = false;
             bool lastShadowsKeywordState = false;
             bool lastSoftShadowsKeywordState = false;
@@ -933,6 +928,7 @@ void RenderStencilPointLights(RasterCommandBuffer cmd, bool stripShadowsOffVaria
                 if (light.bakingOutput.lightmapBakeType == LightmapBakeType.Mixed)
                     lightFlags |= (int)LightFlag.SubtractiveMixedLighting;
 
+                // Determine whether the light is casting shadows and what the index it should use.
                 int shadowLightIndex = hasAdditionalLightPass ? m_AdditionalLightsShadowCasterPass.GetShadowLightIndexFromLightIndex(visLightIndex) : -1;
                 bool hasDeferredShadows = light && light.shadows != LightShadows.None && shadowLightIndex >= 0;
 
@@ -962,23 +958,22 @@ void RenderStencilPointLights(RasterCommandBuffer cmd, bool stripShadowsOffVaria
             cmd.SetKeyword(ShaderGlobalKeywords._POINT, false);
         }
 
-        void RenderStencilSpotLights(RasterCommandBuffer cmd, bool stripShadowsOffVariants, UniversalLightData lightData, UniversalShadowData shadowData, NativeArray<VisibleLight> visibleLights)
+        void RenderStencilSpotLights(RasterCommandBuffer cmd, bool stripShadowsOffVariants, UniversalLightData lightData, UniversalShadowData shadowData, NativeArray<VisibleLight> visibleLights, bool hasAdditionalLightPass, bool hasLightCookieManager)
         {
             if (m_HemisphereMesh == null)
                 m_HemisphereMesh = CreateHemisphereMesh();
 
             cmd.SetKeyword(ShaderGlobalKeywords._SPOT, true);
 
-            bool isFirstLight = true;
-            bool hasLightCookieManager = m_LightCookieManager != null;
-            bool hasAdditionalLightPass = m_AdditionalLightsShadowCasterPass != null;
             int lastLightCookieIndex = -1;
+            bool isFirstLight = true;
             bool lastLightCookieKeywordState = false;
             bool lastShadowsKeywordState = false;
             bool lastSoftShadowsKeywordState = false;
             for (int soffset = m_stencilVisLightOffsets[(int)LightType.Spot]; soffset < m_stencilVisLights.Length; ++soffset)
             {
                 ushort visLightIndex = m_stencilVisLights[soffset];
+
                 ref VisibleLight vl = ref visibleLights.UnsafeElementAtMutable(visLightIndex);
                 if (vl.lightType != LightType.Spot)
                     break;
@@ -993,8 +988,7 @@ void RenderStencilSpotLights(RasterCommandBuffer cmd, bool stripShadowsOffVarian
                 // The tighter the spot shape, the lesser inflation is needed.
                 float guard = Mathf.Lerp(1.0f, kStencilShapeGuard, sinAlpha);
 
-                Vector4 lightPos, lightColor, lightAttenuation, lightSpotDir, lightOcclusionChannel;
-                UniversalRenderPipeline.InitializeLightConstants_Common(visibleLights, visLightIndex, out lightPos, out lightColor, out lightAttenuation, out lightSpotDir, out lightOcclusionChannel);
+                UniversalRenderPipeline.InitializeLightConstants_Common(visibleLights, visLightIndex, out Vector4 lightPos, out Vector4 lightColor, out Vector4 lightAttenuation, out Vector4 lightSpotDir, out Vector4 lightOcclusionChannel);
 
                 if (lightData.supportsLightLayers)
                     SetRenderingLayersMask(cmd, light, ShaderConstants._LightLayerMask);
@@ -1003,6 +997,7 @@ void RenderStencilSpotLights(RasterCommandBuffer cmd, bool stripShadowsOffVarian
                 if (light.bakingOutput.lightmapBakeType == LightmapBakeType.Mixed)
                     lightFlags |= (int)LightFlag.SubtractiveMixedLighting;
 
+                // Determine whether the light is casting shadows and what the index it should use.
                 int shadowLightIndex = hasAdditionalLightPass ? m_AdditionalLightsShadowCasterPass.GetShadowLightIndexFromLightIndex(visLightIndex) : -1;
                 bool hasDeferredShadows = light && light.shadows != LightShadows.None && shadowLightIndex >= 0;
 
@@ -1032,7 +1027,6 @@ void RenderStencilSpotLights(RasterCommandBuffer cmd, bool stripShadowsOffVarian
 
                 isFirstLight = false;
             }
-
             cmd.SetKeyword(ShaderGlobalKeywords._SPOT, false);
         }
 

Packages/com.unity.render-pipelines.universal/Runtime/Passes/AdditionalLightsShadowAtlasLayout.cs

@@ -339,7 +339,7 @@ static int EstimateScaleFactorNeededToFitAllShadowsInAtlas(in NativeArray<Shadow
         }
 
         // Sort array in decreasing requestedResolution order,
-        // sub-sorting in "HardShadow > SoftShadow" and then "Spot > Point",
+        // sub-sorting in "HardShadow > SoftShadow",
         //   i.e place last requests that will be removed in priority to make room for the others,
         //   because their resolution is too small to produce good-looking shadows ; or because they take relatively more space in the atlas )
         // sub-sub-sorting in light distance to camera
@@ -350,10 +350,9 @@ static Func<ShadowResolutionRequest, ShadowResolutionRequest, int> CreateCompare
             {
                 return (((curr.requestedResolution > other.requestedResolution)
                          || (curr.requestedResolution == other.requestedResolution && !curr.softShadow && other.softShadow)
-                         || (curr.requestedResolution == other.requestedResolution && curr.softShadow == other.softShadow && !curr.pointLightShadow && other.pointLightShadow)
-                         || (curr.requestedResolution == other.requestedResolution && curr.softShadow == other.softShadow && curr.pointLightShadow == other.pointLightShadow && s_VisibleLightIndexToCameraSquareDistance[curr.visibleLightIndex] < s_VisibleLightIndexToCameraSquareDistance[other.visibleLightIndex])
-                         || (curr.requestedResolution == other.requestedResolution && curr.softShadow == other.softShadow && curr.pointLightShadow == other.pointLightShadow && s_VisibleLightIndexToCameraSquareDistance[curr.visibleLightIndex] == s_VisibleLightIndexToCameraSquareDistance[other.visibleLightIndex] && curr.visibleLightIndex < other.visibleLightIndex)
-                         || (curr.requestedResolution == other.requestedResolution && curr.softShadow == other.softShadow && curr.pointLightShadow == other.pointLightShadow && s_VisibleLightIndexToCameraSquareDistance[curr.visibleLightIndex] == s_VisibleLightIndexToCameraSquareDistance[other.visibleLightIndex] && curr.visibleLightIndex == other.visibleLightIndex && curr.perLightShadowSliceIndex < other.perLightShadowSliceIndex)))
+                         || (curr.requestedResolution == other.requestedResolution && curr.softShadow == other.softShadow && s_VisibleLightIndexToCameraSquareDistance[curr.visibleLightIndex] < s_VisibleLightIndexToCameraSquareDistance[other.visibleLightIndex])
+                         || (curr.requestedResolution == other.requestedResolution && curr.softShadow == other.softShadow && s_VisibleLightIndexToCameraSquareDistance[curr.visibleLightIndex] == s_VisibleLightIndexToCameraSquareDistance[other.visibleLightIndex] && curr.visibleLightIndex < other.visibleLightIndex)
+                         || (curr.requestedResolution == other.requestedResolution && curr.softShadow == other.softShadow && s_VisibleLightIndexToCameraSquareDistance[curr.visibleLightIndex] == s_VisibleLightIndexToCameraSquareDistance[other.visibleLightIndex] && curr.visibleLightIndex == other.visibleLightIndex && curr.perLightShadowSliceIndex < other.perLightShadowSliceIndex)))
                     ? -1 : 1;
             };
         }