Simplified gathering of color, depth and motion vector RTs by using the game camera texture directly, and blitting just before dispatch.

This gets rid of all the OnRenderImage song and dance in the game camera component, and requires less keeping track of instance variables.

Assets/Scripts/Fsr2Controller.cs

@@ -37,7 +37,6 @@ public class Fsr2Controller : MonoBehaviour
     private Fsr2Context _context;
     private readonly Fsr2.DispatchDescription _dispatchDescription = new Fsr2.DispatchDescription();
 
-    private RenderTexture _colorRT, _depthRT, _motionVectorsRT;
     private RenderTexture _outputRT;
 
     private Material _copyDepthMat;
@@ -89,6 +88,7 @@ public class Fsr2Controller : MonoBehaviour
         _context = Fsr2.CreateContext(DisplaySize, RenderSize);
 
         // TODO: do we need a depth buffer for the output? We will need depth & motion vectors for subsequent post-FX. How should FSR2 output these?
+        // TODO: can probably be a temporary RT
         _outputRT = new RenderTexture(DisplaySize.x, DisplaySize.y, 24, RenderTextureFormat.ARGBHalf) { enableRandomWrite = true };
         _outputRT.Create();
     }
@@ -110,22 +110,8 @@ public class Fsr2Controller : MonoBehaviour
         RenderPipelineManager.endContextRendering -= OnEndContextRendering;
     }
 
-    public void OnRenderGameCamera(RenderTexture renderTarget, Vector2 jitterOffset)
+    public void SetJitterOffset(Vector2 jitterOffset)
     {
-        // I hate having to allocate extra RTs just to duplicate already existing Unity render buffers, but AFAIK there is no way to directly address these buffers individually from code 
-        _colorRT = RenderTexture.GetTemporary(renderTarget.width, renderTarget.height, 0, RenderTextureFormat.ARGBHalf);
-        _depthRT = RenderTexture.GetTemporary(renderTarget.width, renderTarget.height, 0, RenderTextureFormat.RFloat);
-        _motionVectorsRT = RenderTexture.GetTemporary(renderTarget.width, renderTarget.height, 0, RenderTextureFormat.RGHalf);
-        
-        // TODO: might be able to combine color + depth into a single RT and separate them out using RenderTextureSubElement
-        // TODO: we can copy to all RTs at the same time using a multi-target blit, requiring only a single shader + material
-        Graphics.Blit(renderTarget, _colorRT);
-        Graphics.Blit(renderTarget, _depthRT, CopyDepthMaterial);
-        Graphics.Blit(renderTarget, _motionVectorsRT, CopyMotionVectorsMaterial);
-
-        _dispatchDescription.Color = _colorRT;
-        _dispatchDescription.Depth = _depthRT;
-        _dispatchDescription.MotionVectors = _motionVectorsRT;
         _dispatchDescription.JitterOffset = jitterOffset;
     }
 
@@ -138,10 +124,20 @@ public class Fsr2Controller : MonoBehaviour
     // For legacy built-in render pipeline
     private void OnRenderImage(RenderTexture src, RenderTexture dest)
     {
-        // Ensure the input resources were updated correctly before upscaling
-        if (_colorRT == null || _depthRT == null || _motionVectorsRT == null)
-            return;
+        var color = gameCamera.targetTexture;
+        
+        // I hate having to allocate extra RTs just to duplicate already existing Unity render buffers, but AFAIK there is no way to directly address these buffers individually from code
+        var depth = RenderTexture.GetTemporary(color.width, color.height, 0, RenderTextureFormat.RFloat);
+        var motionVectors = RenderTexture.GetTemporary(color.width, color.height, 0, RenderTextureFormat.RGHalf);
+        
+        // TODO: might be able to combine color + depth into a single RT and separate them out using RenderTextureSubElement
+        // TODO: we can copy to all RTs at the same time using a multi-target blit, requiring only a single shader + material
+        Graphics.Blit(color, depth, CopyDepthMaterial);
+        Graphics.Blit(color, motionVectors, CopyMotionVectorsMaterial);
 
+        _dispatchDescription.Color = color;
+        _dispatchDescription.Depth = depth;
+        _dispatchDescription.MotionVectors = motionVectors;
         _dispatchDescription.Output = _outputRT;
         _dispatchDescription.Exposure = null;
         _dispatchDescription.Reactive = null;
@@ -158,10 +154,8 @@ public class Fsr2Controller : MonoBehaviour
 
         _context.Dispatch(_dispatchDescription);
         
-        RenderTexture.ReleaseTemporary(_colorRT);
-        RenderTexture.ReleaseTemporary(_depthRT);
-        RenderTexture.ReleaseTemporary(_motionVectorsRT);
-        _colorRT = _depthRT = _motionVectorsRT = null;
+        RenderTexture.ReleaseTemporary(depth);
+        RenderTexture.ReleaseTemporary(motionVectors);
         
         // Output upscaled image to screen
         Graphics.Blit(_outputRT, dest);

Assets/Scripts/SubsampleTest.cs

@@ -19,7 +19,6 @@ public class SubsampleTest : MonoBehaviour
     private bool enableJitter;
 
     private Fsr2Controller _fsr2Controller;
-    private Vector2 _jitterOffset;
     
     private void OnEnable()
     {
@@ -86,13 +85,13 @@ public class SubsampleTest : MonoBehaviour
         outputCamera.clearFlags = CameraClearFlags.Color;
     }
 
-    private Rect tempRect;
+    private Rect _tempRect;
     
     private void OnPreRender()
     {
         gameCamera.aspect = (Screen.width * gameCamera.rect.width) / (Screen.height * gameCamera.rect.height);
         
-        tempRect = gameCamera.rect;
+        _tempRect = gameCamera.rect;
         gameCamera.rect = new Rect(0, 0, 1, 1);
 
         if (enableJitter)
@@ -100,28 +99,21 @@ public class SubsampleTest : MonoBehaviour
             // Perform custom jittering of the camera's projection matrix according to FSR2's instructions
             // Unity already does jittering behind the scenes for certain post-effects, so can we perhaps integrate with that? 
             int jitterPhaseCount = Fsr2.GetJitterPhaseCount(gameCamera.targetTexture.width, Screen.width);
-            Fsr2.GetJitterOffset(out _jitterOffset.x, out _jitterOffset.y, Time.frameCount, jitterPhaseCount);
+            Fsr2.GetJitterOffset(out float jitterX, out float jitterY, Time.frameCount, jitterPhaseCount);
 
-            float jitterX = 2.0f * _jitterOffset.x / gameCamera.targetTexture.width;
-            float jitterY = -2.0f * _jitterOffset.y / gameCamera.targetTexture.height;
+            jitterX = 2.0f * jitterX / gameCamera.targetTexture.width;
+            jitterY = -2.0f * jitterY / gameCamera.targetTexture.height;
 
             var jitterTranslationMatrix = Matrix4x4.Translate(new Vector3(jitterX, jitterY, 0));
             gameCamera.projectionMatrix = jitterTranslationMatrix * gameCamera.nonJitteredProjectionMatrix;
-        }
-    }
             
-    private void OnRenderImage(RenderTexture src, RenderTexture dest)
-    {
-        // We don't actually output any image from this camera; instead we pass its render buffers on to the FSR2 system
-        _fsr2Controller.OnRenderGameCamera(src, _jitterOffset);
-        
-        // Shut up Unity warning about not writing anything to the destination texture
-        Graphics.SetRenderTarget(dest);
+            _fsr2Controller.SetJitterOffset(new Vector2(jitterX, jitterY));
+        }
     }
 
     private void OnPostRender()
     {
-        gameCamera.rect = tempRect;
+        gameCamera.rect = _tempRect;
         gameCamera.ResetProjectionMatrix();
     }
 }