[Port] [Forward] Clear indirect arguments buffer for local fog volumes.

Author: svc-reach-platform-support

Packages/com.unity.render-pipelines.high-definition/Runtime/Lighting/VolumetricLighting/HDRenderPipeline.VolumetricLighting.cs

@@ -1051,11 +1051,13 @@ class VolumetricFogVoxelizationPassData
             public bool fogOverdrawDebugEnabled;
 
             // Regular fogs
+            public ComputeShader clearVolumetricMaterialCS;
             public ComputeShader volumetricMaterialCS;
             public GraphicsBuffer globalIndirectBuffer;
             public GraphicsBuffer globalIndirectionBuffer;
             public GraphicsBuffer materialDataBuffer;
             public GraphicsBuffer visibleVolumeGlobalIndices;
+            public int clearRenderingParametersKernel;
             public int computeRenderingParametersKernel;
             public ComputeBuffer visibleVolumeBoundsBuffer;
         }
@@ -1210,7 +1212,9 @@ unsafe TextureHandle FogVolumeAndVFXVoxelizationPass(RenderGraph renderGraph,
                         passData.vfxDebugRendererList = renderGraph.CreateRendererList(vfxDebugFogRenderListDesc);
                         builder.UseRendererList(passData.vfxDebugRendererList);
                     }
+                    passData.clearVolumetricMaterialCS = runtimeShaders.clearVolumetricMaterialCS;
                     passData.volumetricMaterialCS = runtimeShaders.volumetricMaterialCS;
+                    passData.clearRenderingParametersKernel = passData.clearVolumetricMaterialCS.FindKernel("Clear");
                     passData.computeRenderingParametersKernel = passData.volumetricMaterialCS.FindKernel("ComputeVolumetricMaterialRenderingParameters");
                     passData.visibleVolumeBoundsBuffer = visibleVolumeBoundsBuffer;
                     passData.globalIndirectBuffer = LocalVolumetricFogManager.manager.globalIndirectBuffer;
@@ -1226,6 +1230,13 @@ unsafe TextureHandle FogVolumeAndVFXVoxelizationPass(RenderGraph renderGraph,
                         {
                             var natCmd = CommandBufferHelpers.GetNativeCommandBuffer(ctx.cmd);
 
+                            // Clear the indirect arguments.
+                            natCmd.SetComputeBufferParam(data.clearVolumetricMaterialCS, data.clearRenderingParametersKernel, HDShaderIDs._VolumetricGlobalIndirectArgsBuffer, data.globalIndirectBuffer);
+                            natCmd.SetComputeIntParam(data.clearVolumetricMaterialCS, HDShaderIDs._MaxVolumeCount, data.globalIndirectBuffer.count);
+
+                            int dispatchXCount = HDUtils.DivRoundUp(data.globalIndirectBuffer.count, 64);
+                            natCmd.DispatchCompute(data.clearVolumetricMaterialCS, data.clearRenderingParametersKernel, dispatchXCount, 1, 1);
+
                             // Prepare draw indirect command for the draw
                             int volumeCount = data.volumetricFogs.Count;
 
@@ -1240,7 +1251,7 @@ unsafe TextureHandle FogVolumeAndVFXVoxelizationPass(RenderGraph renderGraph,
                             natCmd.SetComputeIntParam(data.volumetricMaterialCS, HDShaderIDs._VolumetricViewCount, data.hdCamera.viewCount);
                             ConstantBuffer.PushGlobal(natCmd, data.volumetricCB, HDShaderIDs._ShaderVariablesVolumetric);
 
-                            int dispatchXCount = Mathf.Max(1, Mathf.CeilToInt((float)(volumeCount * data.hdCamera.viewCount) / 32.0f));
+                            dispatchXCount = Mathf.Max(1, Mathf.CeilToInt((float)(volumeCount * data.hdCamera.viewCount) / 32.0f));
                             natCmd.DispatchCompute(data.volumetricMaterialCS, data.computeRenderingParametersKernel, dispatchXCount, 1, 1);
 
                             natCmd.SetGlobalBuffer(HDShaderIDs._VolumetricGlobalIndirectionBuffer, data.globalIndirectionBuffer);

Packages/com.unity.render-pipelines.high-definition/Runtime/Material/VolumetricMaterial/ClearVolumetricMaterial.compute

@@ -0,0 +1,25 @@
+#pragma only_renderers d3d11 playstation xboxone xboxseries vulkan metal switch switch2
+
+#pragma kernel Clear
+
+#include "Packages/com.unity.render-pipelines.core/ShaderLibrary/Common.hlsl"
+#include "Packages/com.unity.render-pipelines.high-definition/Runtime/ShaderLibrary/ShaderVariables.hlsl"
+
+uint _MaxVolumeCount;
+
+RWBuffer<uint> _VolumetricGlobalIndirectArgsBuffer;
+
+[numthreads(64, 1, 1)]
+void Clear(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    if (dispatchThreadID.x >= _MaxVolumeCount)
+        return;
+
+    uint volumeIndex = dispatchThreadID.x;
+
+    _VolumetricGlobalIndirectArgsBuffer[volumeIndex * 5 + 0] = 0; // IndexCountPerInstance
+    _VolumetricGlobalIndirectArgsBuffer[volumeIndex * 5 + 1] = 0; // InstanceCount
+    _VolumetricGlobalIndirectArgsBuffer[volumeIndex * 5 + 2] = 0; // StartIndexLocation
+    _VolumetricGlobalIndirectArgsBuffer[volumeIndex * 5 + 3] = 0; // BaseVertexLocation
+    _VolumetricGlobalIndirectArgsBuffer[volumeIndex * 5 + 4] = 0; // StartInstanceLocation
+}

Packages/com.unity.render-pipelines.high-definition/Runtime/Material/VolumetricMaterial/ClearVolumetricMaterial.compute.meta

@@ -1206,6 +1206,7 @@ static class HDShaderIDs
 
         // Volumetric Materials
         public static readonly int _VolumeCount = Shader.PropertyToID("_VolumeCount");
+        public static readonly int _MaxVolumeCount = Shader.PropertyToID("_MaxVolumeCount");
         public static readonly int _MaxSliceCount = Shader.PropertyToID("_MaxSliceCount");
         public static readonly int _VolumetricGlobalIndirectArgsBuffer = Shader.PropertyToID("_VolumetricGlobalIndirectArgsBuffer");
         public static readonly int _VolumetricGlobalIndirectionBuffer = Shader.PropertyToID("_VolumetricGlobalIndirectionBuffer");

Packages/com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/HDStringConstants.cs

@@ -120,7 +120,7 @@ public Shader copyDepthBufferPS
             get => m_CopyDepthBufferPS;
             set => this.SetValueAndNotify(ref m_CopyDepthBufferPS, value);
         }
-		
+
         [SerializeField, ResourcePath("Runtime/ShaderLibrary/Blit.shader")]
         private Shader m_BlitPS;
 
@@ -822,6 +822,15 @@ public ComputeShader volumetricMaterialCS
             set => this.SetValueAndNotify(ref m_VolumetricMaterialCS, value);
         }
 
+        [SerializeField, ResourcePath("Runtime/Material/VolumetricMaterial/ClearVolumetricMaterial.compute")]
+        private ComputeShader m_ClearVolumetricMaterialCS;
+
+        public ComputeShader clearVolumetricMaterialCS
+        {
+            get => m_ClearVolumetricMaterialCS;
+            set => this.SetValueAndNotify(ref m_ClearVolumetricMaterialCS, value);
+        }
+
         [SerializeField, ResourcePath("Runtime/Material/Eye/EyeCausticLUTGen.compute")]
         private ComputeShader m_EyeMaterialCS;