[Port] [2021.3] Fix DRS + CustomPass AfterPostprocess and camera depth

Author: svc-reach-platform-support

Packages/com.unity.render-pipelines.high-definition/Editor/RenderPipeline/CustomPass/CustomPassDrawer.cs

@@ -167,6 +167,16 @@ void DoCommonSettingsGUI(ref Rect rect)
             {
                 EditorGUI.PropertyField(rect, m_TargetDepthBuffer, Styles.targetDepthBuffer);
                 rect.y += Styles.defaultLineSpace;
+
+                CustomPass.TargetBuffer requestedDepth = m_TargetDepthBuffer.GetEnumValue<CustomPass.TargetBuffer>();
+                if (m_CustomPass.getConstrainedDepthBuffer() != requestedDepth)
+                {
+                    Rect helpBoxRect = rect;
+                    float helpBoxHeight = EditorGUIUtility.singleLineHeight * 2;
+                    helpBoxRect.height = helpBoxHeight;
+                    EditorGUI.HelpBox(helpBoxRect, "Camera depth isn't supported when dynamic scaling is on. We will automatically fall back to not doing depth-testing for this pass.", MessageType.Warning);
+                    rect.y += helpBoxHeight;
+                }
             }
 
             if ((commonPassUIFlags & PassUIFlag.ClearFlags) != 0)
@@ -259,6 +269,13 @@ internal float GetPropertyHeight(SerializedProperty property, GUIContent label)
                 }
 
                 height += Styles.defaultLineSpace * lines;
+
+                // Add height for the help box if it will be shown
+                if ((commonPassUIFlags & PassUIFlag.TargetDepthBuffer) != 0 &&
+                    m_CustomPass.getConstrainedDepthBuffer() != m_TargetDepthBuffer.GetEnumValue<CustomPass.TargetBuffer>())
+                {
+                    height += EditorGUIUtility.singleLineHeight * 2; // Help box height
+                }
             }
 
             return height + GetPassHeight(property);

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

@@ -52,6 +52,24 @@ internal ProfilingSampler profilingSampler
         /// </summary>
         public TargetBuffer targetDepthBuffer;
 
+        // The actual depth buffer has to follow some constraints, and thus may not be the same result as the target
+        // depth buffer that the user has requested. Apply these constraints and return a result.
+        internal TargetBuffer getConstrainedDepthBuffer()
+        {
+            TargetBuffer depth = targetDepthBuffer;
+            if (depth == TargetBuffer.Camera &&
+                HDRenderPipeline.currentAsset.currentPlatformRenderPipelineSettings.dynamicResolutionSettings.enabled &&
+                currentHDCamera.allowDynamicResolution &&
+                injectionPoint == CustomPassInjectionPoint.AfterPostProcess)
+            {
+                // This custom pass is injected after postprocessing, and Dynamic Resolution Scaling is enabled, which
+                // means an upscaler is active. In this case, the camera color buffer is the full display resolution,
+                // but the camera depth buffer is a lower, pre-upscale resolution. So we cannot do depth testing here.
+                depth = TargetBuffer.None;
+            }
+            return depth;
+        }
+
         /// <summary>
         /// What clear to apply when the color and depth buffer are bound
         /// </summary>
@@ -270,7 +288,7 @@ internal void ExecuteInternal(RenderGraph renderGraph, HDCamera hdCamera, Cullin
                         customPass.isExecuting = false;
 
                         // Set back the camera color buffer if we were using a custom buffer as target
-                        if (customPass.targetDepthBuffer != TargetBuffer.Camera)
+                        if (customPass.getConstrainedDepthBuffer() != TargetBuffer.Camera)
                             CoreUtils.SetRenderTarget(ctx.cmd, outputColorBuffer);
                     });
             }
@@ -307,16 +325,17 @@ bool IsMSAAEnabled(HDCamera hdCamera)
         // This function must be only called from the ExecuteInternal method (requires current render target and current RT manager)
         void SetCustomPassTarget(CommandBuffer cmd)
         {
+            TargetBuffer depth = getConstrainedDepthBuffer();
             // In case all the buffer are set to none, we can't bind anything
-            if (targetColorBuffer == TargetBuffer.None && targetDepthBuffer == TargetBuffer.None)
+            if (targetColorBuffer == TargetBuffer.None && depth == TargetBuffer.None)
                 return;
 
             RTHandle colorBuffer = (targetColorBuffer == TargetBuffer.Custom) ? currentRenderTarget.customColorBuffer.Value : currentRenderTarget.colorBufferRG;
-            RTHandle depthBuffer = (targetDepthBuffer == TargetBuffer.Custom) ? currentRenderTarget.customDepthBuffer.Value : currentRenderTarget.depthBufferRG;
+            RTHandle depthBuffer = (depth == TargetBuffer.Custom) ? currentRenderTarget.customDepthBuffer.Value : currentRenderTarget.depthBufferRG;
 
-            if (targetColorBuffer == TargetBuffer.None && targetDepthBuffer != TargetBuffer.None)
+            if (targetColorBuffer == TargetBuffer.None && depth != TargetBuffer.None)
                 CoreUtils.SetRenderTarget(cmd, depthBuffer, clearFlags);
-            else if (targetColorBuffer != TargetBuffer.None && targetDepthBuffer == TargetBuffer.None)
+            else if (targetColorBuffer != TargetBuffer.None && depth == TargetBuffer.None)
                 CoreUtils.SetRenderTarget(cmd, colorBuffer, clearFlags);
             else
             {