[HDRP] Added a RenderGraph pass that resets the camera size after the dynamic res upscale (#3070)

* Added a RenderGraph pass that resets the camera size after the dynamic res upscale

* Updated changelog

# Conflicts:
#	com.unity.render-pipelines.high-definition/CHANGELOG.md

* fixed class name

* update class name

* PR fix

* Fixed RTHandle scale

Co-authored-by: sebastienlagarde <sebastien@unity3d.com>

Author: alelievr

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Fixed
 - Fixed GC allocations from XR occlusion mesh when using multipass.
 - Fixed XR depth copy when using MSAA.
+- Fixed after post process custom pass scale issue when dynamic resolution is enabled (case 1299194).
 
 ### Changed
 - Change the source value for the ray tracing frame index iterator from m_FrameCount to the camera frame count (case 1301356).

com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Camera/HDCamera.cs

@@ -343,6 +343,8 @@ internal GameObject exposureTarget
 
         internal bool stopNaNs => m_AdditionalCameraData != null && m_AdditionalCameraData.stopNaNs;
 
+        internal bool allowDynamicResolution => m_AdditionalCameraData != null && m_AdditionalCameraData.allowDynamicResolution;
+
         internal HDPhysicalCamera physicalParameters { get; private set; }
 
         internal IEnumerable<AOVRequestData> aovRequests =>

com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/HDRenderPipeline.RenderGraph.cs

@@ -275,6 +275,8 @@ void ExecuteWithRenderGraph(RenderRequest           renderRequest,
             }
             PushFullScreenExposureDebugTexture(m_RenderGraph, postProcessDest);
 
+            ResetCameraSizeForAfterPostProcess(m_RenderGraph, hdCamera, commandBuffer);
+
             RenderCustomPass(m_RenderGraph, hdCamera, postProcessDest, prepassOutput, customPassCullingResults, cullingResults, CustomPassInjectionPoint.AfterPostProcess, aovRequest, aovCustomPassBuffers);
 
             CopyXRDepth(m_RenderGraph, hdCamera, prepassOutput.resolvedDepthBuffer, backBuffer);
@@ -1542,6 +1544,34 @@ bool RenderCustomPass(RenderGraph                 renderGraph,
             return executed;
         }
 
+        class ResetCameraSizeForAfterPostProcessPassData
+        {
+            public HDCamera hdCamera;
+            public ShaderVariablesGlobal shaderVariablesGlobal;
+        }
+
+        void ResetCameraSizeForAfterPostProcess(RenderGraph renderGraph, HDCamera hdCamera, CommandBuffer commandBuffer)
+        {
+            if (DynamicResolutionHandler.instance.DynamicResolutionEnabled())
+            {
+                using (var builder = renderGraph.AddRenderPass("Reset Camera Size After Post Process", out ResetCameraSizeForAfterPostProcessPassData passData))
+                {
+                    passData.hdCamera = hdCamera;
+                    passData.shaderVariablesGlobal = m_ShaderVariablesGlobalCB;
+                    builder.AllowPassCulling(false);
+
+                    builder.SetRenderFunc(
+                        (ResetCameraSizeForAfterPostProcessPassData data, RenderGraphContext ctx) =>
+                        {
+                            data.shaderVariablesGlobal._ScreenSize = new Vector4(data.hdCamera.finalViewport.width, data.hdCamera.finalViewport.height, 1.0f / data.hdCamera.finalViewport.width, 1.0f / data.hdCamera.finalViewport.height);
+                            data.shaderVariablesGlobal._RTHandleScale = RTHandles.rtHandleProperties.rtHandleScale;
+                            ConstantBuffer.PushGlobal(ctx.cmd, data.shaderVariablesGlobal, HDShaderIDs._ShaderVariablesGlobal);
+                            RTHandles.SetReferenceSize((int)data.hdCamera.finalViewport.width, (int)data.hdCamera.finalViewport.height, data.hdCamera.msaaSamples);
+                        });
+                }
+            }
+        }
+
         class BindCustomPassBuffersPassData
         {
             public Lazy<RTHandle> customColorTexture;