[HDRP] Add custom pass buffer scaling functions

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

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Added
 - Added a SG node to get the main directional light direction.
+- Added new functions that sample the custom buffer in custom passes (CustomPassSampleCustomColor and CustomPassLoadCustomColor) to handle the RTHandleScale automatically.
 
 ### Changed
 - MaterialReimporter.ReimportAllMaterials and MaterialReimporter.ReimportAllHDShaderGraphs now batch the asset database changes to improve performance.
@@ -26,6 +27,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed overwriting of preview camera background color. [case 1357004](https://issuetracker.unity3d.com/product/unity/issues/guid/1361557/)
 - Fixed selection of light types (point, area, directional) for path-traced Unlit shadow mattes.
 - Fixed precision issues with the scene voxelization for APV, especially with geometry at the origin.
+- Fixed scaling issues with dynamic resolution and the CustomPassSampleCameraColor function.
 
 ## [13.0.0] - 2021-09-01
 

com.unity.render-pipelines.high-definition/Documentation~/Custom-Pass-Creating.md

@@ -463,6 +463,11 @@ You can also load custom buffers using the following functions:
 - `LoadCustomColor(uint2 pixelCoords)`
 - `LoadCustomDepth(uint2 pixelCoords)`
 
+Note that depending on the injection point used for the Fullscreen custom pass, sampling the custom buffer can result in incorrect scaling. Thus it's recommended to use these functions instead:
+
+- `CustomPassSampleCustomColor(float2 uv)`
+- `CustomPassLoadCustomColor(uint2 pixelCoords)`
+
 HDRP sets the custom pass target buffers to the Camera buffers by default. However, you can select a custom buffer in the UI of the Custom Pass. To do this, go to your Custom Pass component and change the **Target Color Buffer** or **Target Depth Buffer** properties.
 
 To change the buffer format of the Custom Pass component in your HDRP asset, go to **Rendering > Custom Pass > Custom Buffer Format** and select one of the following formats from the drop down menu:

com.unity.render-pipelines.high-definition/Editor/RenderPipeline/CustomPass/CustomPassFullScreenShader.template

@@ -23,8 +23,8 @@ Shader "FullScreen/#SCRIPTNAME#"
     // To sample custom buffers, you have access to these functions:
     // But be careful, on most platforms you can't sample to the bound color buffer. It means that you
     // can't use the SampleCustomColor when the pass color buffer is set to custom (and same for camera the buffer).
-    // float4 SampleCustomColor(float2 uv);
-    // float4 LoadCustomColor(uint2 pixelCoords);
+    // float4 CustomPassSampleCustomColor(float2 uv);
+    // float4 CustomPassLoadCustomColor(uint2 pixelCoords);
     // float LoadCustomDepth(uint2 pixelCoords);
     // float SampleCustomDepth(float2 uv);
 

com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/RenderPass/CustomPass/CustomPassCommon.hlsl

@@ -24,9 +24,10 @@ float3 CustomPassSampleCameraColor(float2 uv, float lod, bool uvGuards = true)
         case CUSTOMPASSINJECTIONPOINT_BEFORE_RENDERING: return float3(0, 0, 0);
         // there is no color pyramid yet for before transparent so we can't sample with mips.
         // Also, we don't use _RTHandleScaleHistory to sample because the color pyramid bound is the actual camera color buffer which is at the resolution of the camera
-        case CUSTOMPASSINJECTIONPOINT_BEFORE_TRANSPARENT:
-        case CUSTOMPASSINJECTIONPOINT_BEFORE_PRE_REFRACTION: return SAMPLE_TEXTURE2D_X_LOD(_ColorPyramidTexture, s_trilinear_clamp_sampler, uv * _RTHandleScaleHistory.xy, 0).rgb;
-        case CUSTOMPASSINJECTIONPOINT_AFTER_POST_PROCESS: return SAMPLE_TEXTURE2D_X_LOD(_AfterPostProcessColorBuffer, s_trilinear_clamp_sampler, uv * _RTHandleScaleHistory.xy, 0).rgb;
+        case CUSTOMPASSINJECTIONPOINT_BEFORE_TRANSPARENT: return SAMPLE_TEXTURE2D_X_LOD(_ColorPyramidTexture, s_trilinear_clamp_sampler, uv * _RTHandleScaleHistory.xy, 0).rgb;
+        case CUSTOMPASSINJECTIONPOINT_BEFORE_POST_PROCESS:
+        case CUSTOMPASSINJECTIONPOINT_BEFORE_PRE_REFRACTION: return SAMPLE_TEXTURE2D_X_LOD(_ColorPyramidTexture, s_trilinear_clamp_sampler, uv * _RTHandleScale.xy, 0).rgb;
+        case CUSTOMPASSINJECTIONPOINT_AFTER_POST_PROCESS: return SAMPLE_TEXTURE2D_X_LOD(_AfterPostProcessColorBuffer, s_trilinear_clamp_sampler, uv * _RTHandleScale.zw, 0).rgb;
         default: return SampleCameraColor(uv, lod);
     }
 }
@@ -44,6 +45,20 @@ float3 CustomPassLoadCameraColor(uint2 pixelCoords, float lod)
     }
 }
 
+float4 CustomPassSampleCustomColor(float2 uv)
+{
+    switch ((int)_CustomPassInjectionPoint)
+    {
+        case CUSTOMPASSINJECTIONPOINT_AFTER_POST_PROCESS: return LOAD_TEXTURE2D_X_LOD(_CustomColorTexture, uv * _ScreenSize.xy, 0);
+        default: return SampleCustomColor(uv);
+    }
+}
+
+float4 CustomPassLoadCustomColor(uint2 pixelCoords)
+{
+    return LoadCustomColor(pixelCoords);
+}
+
 struct Attributes
 {
     uint vertexID : SV_VertexID;