Implemented screen scaling through camera viewport manipulation, done through the helper's LateUpdate.

This also led to some reorganization of variables and event ordering.
Added some bloom to the post-process layer to test the cooperation between FSR2 and other post effects.

Assets/Scenes/SampleScenePPV2.unity

@@ -152,7 +152,7 @@ Light:
   m_Type: 1
   m_Shape: 0
   m_Color: {r: 1, g: 0.95686275, b: 0.8392157, a: 1}
-  m_Intensity: 1
+  m_Intensity: 3
   m_Range: 10
   m_SpotAngle: 30
   m_InnerSpotAngle: 21.80208

Assets/Scenes/SampleScenePPV2_Profiles/Main Camera Profile.asset

@@ -14,6 +14,54 @@ MonoBehaviour:
   m_EditorClassIdentifier: 
   settings:
   - {fileID: 3185594499184808736}
+  - {fileID: 318921389242660834}
+--- !u!114 &318921389242660834
+MonoBehaviour:
+  m_ObjectHideFlags: 3
+  m_CorrespondingSourceObject: {fileID: 0}
+  m_PrefabInstance: {fileID: 0}
+  m_PrefabAsset: {fileID: 0}
+  m_GameObject: {fileID: 0}
+  m_Enabled: 1
+  m_EditorHideFlags: 0
+  m_Script: {fileID: 11500000, guid: 48a79b01ea5641d4aa6daa2e23605641, type: 3}
+  m_Name: Bloom
+  m_EditorClassIdentifier: 
+  active: 1
+  enabled:
+    overrideState: 1
+    value: 1
+  intensity:
+    overrideState: 1
+    value: 2
+  threshold:
+    overrideState: 1
+    value: 1
+  softKnee:
+    overrideState: 0
+    value: 0.5
+  clamp:
+    overrideState: 0
+    value: 65472
+  diffusion:
+    overrideState: 1
+    value: 4
+  anamorphicRatio:
+    overrideState: 0
+    value: 0
+  color:
+    overrideState: 0
+    value: {r: 1, g: 1, b: 1, a: 1}
+  fastMode:
+    overrideState: 0
+    value: 0
+  dirtTexture:
+    overrideState: 0
+    value: {fileID: 0}
+    defaultState: 1
+  dirtIntensity:
+    overrideState: 0
+    value: 0
 --- !u!114 &3185594499184808736
 MonoBehaviour:
   m_ObjectHideFlags: 3
@@ -33,6 +81,24 @@ MonoBehaviour:
   qualityMode:
     overrideState: 0
     value: 2
+  performSharpenPass:
+    overrideState: 0
+    value: 1
+  sharpness:
+    overrideState: 0
+    value: 0.8
+  enableFP16:
+    overrideState: 0
+    value: 0
+  enableAutoExposure:
+    overrideState: 0
+    value: 1
+  preExposure:
+    overrideState: 0
+    value: 1
+  autoGenerateReactiveMask:
+    overrideState: 0
+    value: 1
 --- !u!114 &4429786910217829299
 MonoBehaviour:
   m_ObjectHideFlags: 3

Assets/Scripts/Fsr2ImageEffect.cs

@@ -105,7 +105,7 @@ namespace FidelityFX
                 _renderCamera.AddCommandBuffer(CameraEvent.BeforeForwardAlpha, _opaqueInputCommandBuffer);
             }
 
-            // Apply a mipmap bias so that textures retain their original sharpness
+            // Apply a mipmap bias so that textures retain their sharpness
             float biasOffset = Fsr2.GetMipmapBiasOffset(_renderSize.x, _displaySize.x);
             Fsr2.GlobalCallbacks.ApplyMipmapBias(biasOffset);
 

Assets/Scripts/Fsr2PostProcessEffect.cs

@@ -42,10 +42,11 @@ namespace FidelityFX
         private Fsr2Context _fsrContext;
         private Fsr2PostProcessHelper _helper;
 
-        private Vector2Int _displaySize;
-        private Vector2Int _renderSize;
+        private ref Vector2Int DisplaySize => ref _helper.DisplaySize;
+        private ref Vector2Int RenderSize => ref _helper.RenderSize;
         
         private Fsr2.QualityMode _prevQualityMode;
+        private Vector2Int _prevDisplaySize;
         
         public override void Init()
         {
@@ -77,16 +78,6 @@ namespace FidelityFX
                 return;
             }
 
-            // Monitor for any resolution changes and recreate the FSR2 context if necessary
-            // We can't create an FSR2 context without info from the post-processing context, so delay the initial setup until here
-            if (_fsrContext == null || context.screenWidth != _displaySize.x || context.screenHeight != _displaySize.y || settings.qualityMode != _prevQualityMode)
-            {
-                DestroyFsrContext();
-                CreateFsrContext(context);
-                
-                _prevQualityMode = settings.qualityMode;
-            }
-            
             // Ensure that the helper script exists and is enabled
             if (_helper == null || !_helper.enabled)
             {
@@ -100,6 +91,16 @@ namespace FidelityFX
                 return;
             }
             
+            // Monitor for any resolution changes and recreate the FSR2 context if necessary
+            // We can't create an FSR2 context without info from the post-processing context, so delay the initial setup until here
+            if (_fsrContext == null || DisplaySize.x != _prevDisplaySize.x || DisplaySize.y != _prevDisplaySize.y || settings.qualityMode != _prevQualityMode)
+            {
+                DestroyFsrContext();
+                CreateFsrContext(context);
+                
+                _prevQualityMode = settings.qualityMode;
+            }
+
             //Debug.Log("[FSR2] Render, where am I being called from?");  // In OnPreCull... OH
             // TODO: executing in OnPreCull means we can do jittering in here, at least. Rect manipulation should still happen before PPV2 entirely.
             ApplyJitter(context.camera);
@@ -122,9 +123,10 @@ namespace FidelityFX
         
         private void CreateFsrContext(PostProcessRenderContext context)
         {
-            _displaySize = new Vector2Int(context.screenWidth, context.screenHeight);
-            Fsr2.GetRenderResolutionFromQualityMode(out var renderWidth, out var renderHeight, _displaySize.x, _displaySize.y, settings.qualityMode);
-            _renderSize = new Vector2Int(renderWidth, renderHeight);
+            _prevDisplaySize = DisplaySize;
+            
+            Fsr2.GetRenderResolutionFromQualityMode(out var renderWidth, out var renderHeight, DisplaySize.x, DisplaySize.y, settings.qualityMode);
+            RenderSize = new Vector2Int(renderWidth, renderHeight);
             
             Fsr2.InitializationFlags flags = 0;
             if (context.camera.allowHDR) flags |= Fsr2.InitializationFlags.EnableHighDynamicRange;
@@ -135,7 +137,11 @@ namespace FidelityFX
             flags |= Fsr2.InitializationFlags.EnableDebugChecking;
 #endif
             
-            _fsrContext = Fsr2.CreateContext(_displaySize, _renderSize, flags);
+            _fsrContext = Fsr2.CreateContext(DisplaySize, RenderSize, flags);
+
+            // Apply a mipmap bias so that textures retain their sharpness
+            float biasOffset = Fsr2.GetMipmapBiasOffset(RenderSize.x, DisplaySize.x);
+            Fsr2.GlobalCallbacks.ApplyMipmapBias(biasOffset);
         }
         
         private void DestroyFsrContext()
@@ -144,17 +150,21 @@ namespace FidelityFX
             {
                 _fsrContext.Destroy();
                 _fsrContext = null;
+                
+                // Undo the previous mipmap bias adjustment
+                float biasOffset = Fsr2.GetMipmapBiasOffset(RenderSize.x, _prevDisplaySize.x);
+                Fsr2.GlobalCallbacks.ApplyMipmapBias(-biasOffset);
             }
         }
 
         private void ApplyJitter(Camera camera)
         {
             // Perform custom jittering of the camera's projection matrix according to FSR2's recipe
-            int jitterPhaseCount = Fsr2.GetJitterPhaseCount(_renderSize.x, _displaySize.x);
+            int jitterPhaseCount = Fsr2.GetJitterPhaseCount(RenderSize.x, DisplaySize.x);
             Fsr2.GetJitterOffset(out float jitterX, out float jitterY, Time.frameCount, jitterPhaseCount);
 
-            jitterX = 2.0f * jitterX / _renderSize.x;
-            jitterY = 2.0f * jitterY / _renderSize.y;
+            jitterX = 2.0f * jitterX / RenderSize.x;
+            jitterY = 2.0f * jitterY / RenderSize.y;
 
             var jitterTranslationMatrix = Matrix4x4.Translate(new Vector3(jitterX, jitterY, 0));
             camera.nonJitteredProjectionMatrix = camera.projectionMatrix;
@@ -166,26 +176,64 @@ namespace FidelityFX
     internal class Fsr2PostProcessHelper : MonoBehaviour
     {
         internal Fsr2PostProcessEffect Settings;
+        internal Vector2Int DisplaySize;
+        internal Vector2Int RenderSize;
 
         private Camera _camera;
+        private Rect _originalRect;
 
         private void Awake()
         {
             _camera = GetComponent<Camera>();
             // TODO: inject opaque-only command buffer & anything else?
+
+            DisplaySize.x = _camera.pixelWidth;
+            DisplaySize.y = _camera.pixelHeight;
+            RenderSize = DisplaySize;
         }
 
-        private void OnPreCull()    // TODO: may need to do this in LateUpdate instead? So we execute before PPV2's OnPreCull
+        private void Start()
+        {
+            StartCoroutine(CResetCamera());
+        }
+
+        /// <summary>
+        /// This needs to run before PostProcessLayer's OnPreCull, hence why we place this code in LateUpdate.
+        /// </summary>
+        private void LateUpdate()
         {
-            // TODO: check if FSR2 is still enabled; if not: reset PPV2 source texture & disable self
-            // TODO: fiddle with the camera parameters, rect, jitter, etc
-            // Debug.Log("[FSR2] OnPreCull");
+            if (!Settings.enabled)
+            {
+                enabled = false;
+                return;
+            }
+
+            // Relay information about the camera's output size before rescaling
+            DisplaySize.x = _camera.pixelWidth;
+            DisplaySize.y = _camera.pixelHeight;
+            
+            // Render to a smaller portion of the screen by manipulating the camera's viewport rect
+            _originalRect = _camera.rect;
+            _camera.aspect = (_camera.pixelWidth * _originalRect.width) / (_camera.pixelHeight * _originalRect.height);
+            _camera.rect = new Rect(0, 0, _originalRect.width * RenderSize.x / DisplaySize.x, _originalRect.height * RenderSize.y / DisplaySize.y);
         }
 
-        private void OnPostRender()
+        // private void OnPreCull()    // TODO: may need to do this in LateUpdate instead? So we execute before PPV2's OnPreCull
+        // {
+        //     // TODO: check if FSR2 is still enabled; if not: reset PPV2 source texture & disable self
+        //     // TODO: fiddle with the camera parameters, rect, jitter, etc
+        // }
+
+        private IEnumerator CResetCamera()
+        {
+            while (true)
             {
+                yield return new WaitForEndOfFrame();
+
+                _camera.rect = _originalRect;
                 _camera.ResetProjectionMatrix();
             }
         }
+    }
 }
 #endif  // UNITY_POST_PROCESSING_STACK_V2