From b15e3b9c39525898ef5c9e97c4c51a8d30d69ac8 Mon Sep 17 00:00:00 2001
From: Nico de Poel <ndepoel@gmail.com>
Date: Thu, 23 Feb 2023 12:38:43 +0100
Subject: [PATCH] Use temporary render textures for storing color, depth and
 motion vectors copied from the game camera.

---
 Assets/Scripts/Fsr2Controller.cs | 47 ++++++++++++--------------------
 Assets/Scripts/SubsampleTest.cs  |  4 +++
 2 files changed, 21 insertions(+), 30 deletions(-)

diff --git a/Assets/Scripts/Fsr2Controller.cs b/Assets/Scripts/Fsr2Controller.cs
index 483a5cf..a746ab6 100644
--- a/Assets/Scripts/Fsr2Controller.cs
+++ b/Assets/Scripts/Fsr2Controller.cs
@@ -88,17 +88,7 @@ public class Fsr2Controller : MonoBehaviour
         // TODO: enable motion vector jitter cancellation or not?
         _context = Fsr2.CreateContext(DisplaySize, RenderSize);
 
-        // TODO: could make these temporary RTs
-        _colorRT = new RenderTexture(RenderSize.x, RenderSize.y, 0, RenderTextureFormat.ARGBHalf) { name = "FSR2 Color Input" };
-        _colorRT.Create();
-
-        _depthRT = new RenderTexture(RenderSize.x, RenderSize.y, 0, RenderTextureFormat.RFloat) { name = "FSR2 Depth Input" };
-        _depthRT.Create();
-
-        _motionVectorsRT = new RenderTexture(RenderSize.x, RenderSize.y, 0, RenderTextureFormat.RGHalf) { name = "FSR2 Motion Vectors Input" };
-        _motionVectorsRT.Create();
-
-        _outputRT = new RenderTexture(Screen.width, Screen.height, 24, RenderTextureFormat.ARGBHalf) { enableRandomWrite = true };  // TODO: does this need to be a UAV?
+        _outputRT = new RenderTexture(DisplaySize.x, DisplaySize.y, 24, RenderTextureFormat.ARGBHalf) { enableRandomWrite = true };
         _outputRT.Create();
 
         _exposure = new Texture2D(1, 1) { name = "FSR2 Exposure" };
@@ -120,24 +110,6 @@ public class Fsr2Controller : MonoBehaviour
             _outputRT = null;
         }
 
-        if (_motionVectorsRT != null)
-        {
-            _motionVectorsRT.Release();
-            _motionVectorsRT = null;
-        }
-
-        if (_depthRT != null)
-        {
-            _depthRT.Release();
-            _depthRT = null;
-        }
-
-        if (_colorRT != null)
-        {
-            _colorRT.Release();
-            _colorRT = null;
-        }
-
         if (_context != null)
         {
             _context.Destroy();
@@ -149,6 +121,12 @@ public class Fsr2Controller : MonoBehaviour
 
     public void UpdateInputResources(RenderTexture src)
     {
+        // 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 renderSize = RenderSize;
+        _colorRT = RenderTexture.GetTemporary(renderSize.x, renderSize.y, 0, RenderTextureFormat.ARGBHalf);
+        _depthRT = RenderTexture.GetTemporary(renderSize.x, renderSize.y, 0, RenderTextureFormat.RFloat);
+        _motionVectorsRT = RenderTexture.GetTemporary(renderSize.x, renderSize.y, 0, RenderTextureFormat.RGHalf);
+        
         Graphics.Blit(src, _colorRT);
         Graphics.Blit(src, _depthRT, CopyDepthMaterial);
         Graphics.Blit(src, _motionVectorsRT, CopyMotionVectorsMaterial);
@@ -163,6 +141,10 @@ 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;
+        
         _dispatchDescription.Color = _colorRT;
         _dispatchDescription.Depth = _depthRT;
         _dispatchDescription.MotionVectors = _motionVectorsRT;
@@ -181,7 +163,12 @@ public class Fsr2Controller : MonoBehaviour
 
         _context.Dispatch(_dispatchDescription);
         
-        // Output sharpened image to screen
+        RenderTexture.ReleaseTemporary(_colorRT);
+        RenderTexture.ReleaseTemporary(_depthRT);
+        RenderTexture.ReleaseTemporary(_motionVectorsRT);
+        _colorRT = _depthRT = _motionVectorsRT = null;
+        
+        // Output upscaled image to screen
         Graphics.Blit(_outputRT, dest);
     }
 }
diff --git a/Assets/Scripts/SubsampleTest.cs b/Assets/Scripts/SubsampleTest.cs
index f8f9044..d1e091c 100644
--- a/Assets/Scripts/SubsampleTest.cs
+++ b/Assets/Scripts/SubsampleTest.cs
@@ -116,7 +116,11 @@ public class SubsampleTest : MonoBehaviour
 
     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.UpdateInputResources(src);
+        
+        // Shut up Unity warning about not writing anything to the destination texture
+        Graphics.SetRenderTarget(dest);
     }
 
     private void OnPostRender()