Avoid redundant color buffer restores using new Unity 2018.2 CommandBuffer.SetRenderTarget overloads

Author: hkr

PostProcessing/Runtime/PostProcessLayer.cs

@@ -379,7 +379,7 @@ void BuildCommandBuffers()
                 // on tiled GPU as it won't be able to resolve
                 int tempTarget0 = m_TargetPool.Get();
                 context.GetScreenSpaceTemporaryRT(cmd, tempTarget0, 0, sourceFormat);
-                cmd.Blit(cameraTarget, tempTarget0);
+                cmd.BuiltinBlit(cameraTarget, BuiltinRenderTextureType.CurrentActive);
                 context.source = tempTarget0;
 
                 int tempTarget1 = -1;
@@ -424,7 +424,7 @@ void BuildCommandBuffers()
             // tiled GPUs
             int tempRt = m_TargetPool.Get();
             context.GetScreenSpaceTemporaryRT(m_LegacyCmdBuffer, tempRt, 0, sourceFormat, RenderTextureReadWrite.sRGB);
-            m_LegacyCmdBuffer.Blit(cameraTarget, tempRt, RuntimeUtilities.copyStdMaterial, stopNaNPropagation ? 1 : 0);
+            m_LegacyCmdBuffer.BuiltinBlit(cameraTarget, tempRt, RuntimeUtilities.copyStdMaterial, stopNaNPropagation ? 1 : 0);
             if (!m_NaNKilled)
                 m_NaNKilled = stopNaNPropagation;
 

PostProcessing/Runtime/Utils/RuntimeUtilities.cs

@@ -146,12 +146,31 @@ public static PropertySheet copySheet
             }
         }
 
+        public static void SetRenderTargetWithLoadStoreAction(this CommandBuffer cmd, RenderTargetIdentifier rt, RenderBufferLoadAction loadAction, RenderBufferStoreAction storeAction)
+        {
+            #if UNITY_2018_2_OR_NEWER
+            cmd.SetRenderTarget(rt, loadAction, storeAction);
+            #else
+            cmd.SetRenderTarget(rt);
+            #endif
+        }
+        public static void SetRenderTargetWithLoadStoreAction(this CommandBuffer cmd,
+            RenderTargetIdentifier color, RenderBufferLoadAction colorLoadAction, RenderBufferStoreAction colorStoreAction,
+            RenderTargetIdentifier depth, RenderBufferLoadAction depthLoadAction, RenderBufferStoreAction depthStoreAction)
+        {
+            #if UNITY_2018_2_OR_NEWER
+            cmd.SetRenderTarget(color, colorLoadAction, colorStoreAction, depth, depthLoadAction, depthStoreAction);
+            #else
+            cmd.SetRenderTarget(color, depth);
+            #endif
+        }
+
         // Use a custom blit method to draw a fullscreen triangle instead of a fullscreen quad
         // https://michaldrobot.com/2014/04/01/gcn-execution-patterns-in-full-screen-passes/
         public static void BlitFullscreenTriangle(this CommandBuffer cmd, RenderTargetIdentifier source, RenderTargetIdentifier destination, bool clear = false)
         {
             cmd.SetGlobalTexture(ShaderIDs.MainTex, source);
-            cmd.SetRenderTarget(destination);
+            cmd.SetRenderTargetWithLoadStoreAction(destination, RenderBufferLoadAction.DontCare, RenderBufferStoreAction.Store);
 
             if (clear)
                 cmd.ClearRenderTarget(true, true, Color.clear);
@@ -162,7 +181,7 @@ public static void BlitFullscreenTriangle(this CommandBuffer cmd, RenderTargetId
         public static void BlitFullscreenTriangle(this CommandBuffer cmd, RenderTargetIdentifier source, RenderTargetIdentifier destination, PropertySheet propertySheet, int pass, bool clear = false)
         {
             cmd.SetGlobalTexture(ShaderIDs.MainTex, source);
-            cmd.SetRenderTarget(destination);
+            cmd.SetRenderTargetWithLoadStoreAction(destination, RenderBufferLoadAction.DontCare, RenderBufferStoreAction.Store);
 
             if (clear)
                 cmd.ClearRenderTarget(true, true, Color.clear);
@@ -173,10 +192,18 @@ public static void BlitFullscreenTriangle(this CommandBuffer cmd, RenderTargetId
         public static void BlitFullscreenTriangle(this CommandBuffer cmd, RenderTargetIdentifier source, RenderTargetIdentifier destination, RenderTargetIdentifier depth, PropertySheet propertySheet, int pass, bool clear = false)
         {
             cmd.SetGlobalTexture(ShaderIDs.MainTex, source);
-            cmd.SetRenderTarget(destination, depth);
-
+            
             if (clear)
+            {
+                cmd.SetRenderTargetWithLoadStoreAction(destination, RenderBufferLoadAction.DontCare, RenderBufferStoreAction.Store,
+                                                       depth, RenderBufferLoadAction.DontCare, RenderBufferStoreAction.Store);
                 cmd.ClearRenderTarget(true, true, Color.clear);
+            }
+            else
+            {
+                cmd.SetRenderTargetWithLoadStoreAction(destination, RenderBufferLoadAction.DontCare, RenderBufferStoreAction.Store,
+                                                       depth, RenderBufferLoadAction.Load, RenderBufferStoreAction.Store);
+            }
 
             cmd.DrawMesh(fullscreenTriangle, Matrix4x4.identity, propertySheet.material, 0, pass, propertySheet.properties);
         }
@@ -200,11 +227,32 @@ public static void BlitFullscreenTriangle(Texture source, RenderTexture destinat
             if (source != null)
                 material.SetTexture(ShaderIDs.MainTex, source);
 
+            if (destination != null)
+                destination.DiscardContents(true, false);
+
             Graphics.SetRenderTarget(destination);
             Graphics.DrawMeshNow(fullscreenTriangle, Matrix4x4.identity);
             RenderTexture.active = oldRt;
         }
 
+        public static void BuiltinBlit(this CommandBuffer cmd, Rendering.RenderTargetIdentifier source, Rendering.RenderTargetIdentifier dest)
+        {
+            #if UNITY_2018_2_OR_NEWER
+            cmd.SetRenderTarget(dest, RenderBufferLoadAction.DontCare, RenderBufferStoreAction.Store);
+            dest = BuiltinRenderTextureType.CurrentActive;
+            #endif
+            cmd.Blit(source, dest);
+        }
+
+        public static void BuiltinBlit(this CommandBuffer cmd, Rendering.RenderTargetIdentifier source, Rendering.RenderTargetIdentifier dest, Material mat, int pass = 0)
+        {
+            #if UNITY_2018_2_OR_NEWER
+            cmd.SetRenderTarget(dest, RenderBufferLoadAction.DontCare, RenderBufferStoreAction.Store);
+            dest = BuiltinRenderTextureType.CurrentActive;
+            #endif
+            cmd.Blit(source, dest, mat, pass);
+        }
+
         // Fast basic copy texture if available, falls back to blit copy if not
         // Assumes that both textures have the exact same type and format
         public static void CopyTexture(CommandBuffer cmd, RenderTargetIdentifier source, RenderTargetIdentifier destination)