Changed auto-exposure texture into a double buffered resource (FSR3), to avoid issues with reading and writing to the same texture in the compute luminance pass. This allows fast exposure convergence without issues on OpenGL and Metal.

Runtime/FSR3/Fsr3UpscalerContext.cs

@@ -189,7 +189,7 @@ namespace FidelityFX.FSR3
 
             // If auto exposure is enabled use the auto exposure SRV, otherwise what the app sends
             if ((_contextDescription.Flags & Fsr3Upscaler.InitializationFlags.EnableAutoExposure) != 0)
-                dispatchParams.Exposure = new ResourceView(_resources.FrameInfo);
+                dispatchParams.Exposure = new ResourceView(_resources.FrameInfo[frameIndex]);
             else if (!dispatchParams.Exposure.IsValid) 
                 dispatchParams.Exposure = new ResourceView(_resources.DefaultExposure);
 
@@ -236,8 +236,8 @@ namespace FidelityFX.FSR3
                 commandBuffer.ClearRenderTarget(false, true, Color.clear);
                 
                 // Auto exposure always used to track luma changes in locking logic
-                commandBuffer.SetRenderTarget(_resources.FrameInfo);
-                commandBuffer.ClearRenderTarget(false, true, new Color(0f, 1f, 0f, 0f));
+                commandBuffer.SetRenderTarget(_resources.FrameInfo[frameIndex ^ 1]);
+                commandBuffer.ClearRenderTarget(false, true, new Color(0f, 1e8f, 0f, 0f));
 
                 // Reset atomic counter to 0
                 commandBuffer.SetRenderTarget(_resources.SpdAtomicCounter);

Runtime/FSR3/Fsr3UpscalerPass.cs

@@ -155,9 +155,10 @@ namespace FidelityFX.FSR3
         {
             commandBuffer.SetComputeTextureParam(ComputeShader, KernelIndex, Fsr3ShaderIDs.SrvCurrentLuma, Resources.Luma[frameIndex]);
             commandBuffer.SetComputeTextureParam(ComputeShader, KernelIndex, Fsr3ShaderIDs.SrvFarthestDepth, Fsr3ShaderIDs.UavIntermediate);
+            commandBuffer.SetComputeTextureParam(ComputeShader, KernelIndex, Fsr3ShaderIDs.SrvFrameInfo, Resources.FrameInfo[frameIndex ^ 1]);
 
             commandBuffer.SetComputeTextureParam(ComputeShader, KernelIndex, Fsr3ShaderIDs.UavSpdAtomicCount, Resources.SpdAtomicCounter);
-            commandBuffer.SetComputeTextureParam(ComputeShader, KernelIndex, Fsr3ShaderIDs.UavFrameInfo, Resources.FrameInfo);
+            commandBuffer.SetComputeTextureParam(ComputeShader, KernelIndex, Fsr3ShaderIDs.UavFrameInfo, Resources.FrameInfo[frameIndex]);
             commandBuffer.SetComputeTextureParam(ComputeShader, KernelIndex, Fsr3ShaderIDs.UavSpdMip0, Resources.SpdMips, 0);
             commandBuffer.SetComputeTextureParam(ComputeShader, KernelIndex, Fsr3ShaderIDs.UavSpdMip1, Resources.SpdMips, 1);
             commandBuffer.SetComputeTextureParam(ComputeShader, KernelIndex, Fsr3ShaderIDs.UavSpdMip2, Resources.SpdMips, 2);
@@ -273,7 +274,7 @@ namespace FidelityFX.FSR3
             commandBuffer.SetComputeTextureParam(ComputeShader, KernelIndex, Fsr3ShaderIDs.SrvInputExposure, exposure.RenderTarget, exposure.MipLevel, exposure.SubElement);
             commandBuffer.SetComputeTextureParam(ComputeShader, KernelIndex, Fsr3ShaderIDs.SrvDilatedReactiveMasks, Fsr3ShaderIDs.UavDilatedReactiveMasks);
             commandBuffer.SetComputeTextureParam(ComputeShader, KernelIndex, Fsr3ShaderIDs.SrvDilatedMotionVectors, Resources.DilatedVelocity);
-            commandBuffer.SetComputeTextureParam(ComputeShader, KernelIndex, Fsr3ShaderIDs.SrvFrameInfo, Resources.FrameInfo);
+            commandBuffer.SetComputeTextureParam(ComputeShader, KernelIndex, Fsr3ShaderIDs.SrvFrameInfo, Resources.FrameInfo[frameIndex]);
             commandBuffer.SetComputeTextureParam(ComputeShader, KernelIndex, Fsr3ShaderIDs.SrvLumaHistory, Resources.LumaHistory[frameIndex ^ 1]);
             commandBuffer.SetComputeTextureParam(ComputeShader, KernelIndex, Fsr3ShaderIDs.SrvFarthestDepthMip1, Fsr3ShaderIDs.UavFarthestDepthMip1);
             commandBuffer.SetComputeTextureParam(ComputeShader, KernelIndex, Fsr3ShaderIDs.SrvCurrentLuma, Resources.Luma[frameIndex]);

Runtime/FSR3/Fsr3UpscalerResources.cs

@@ -40,10 +40,10 @@ namespace FidelityFX.FSR3
         public RenderTexture DilatedVelocity;
         public RenderTexture DilatedDepth;
         public RenderTexture ReconstructedPrevNearestDepth;
-        public RenderTexture FrameInfo;
         public RenderTexture AutoReactive;
         public RenderTexture AutoComposition;
         
+        public readonly RenderTexture[] FrameInfo = new RenderTexture[2];
         public readonly RenderTexture[] Accumulation = new RenderTexture[2];
         public readonly RenderTexture[] Luma = new RenderTexture[2];
         public readonly RenderTexture[] InternalUpscaled = new RenderTexture[2];
@@ -106,8 +106,7 @@ namespace FidelityFX.FSR3
             ReconstructedPrevNearestDepth.Create();
             
             // Resource FSR3UPSCALER_FrameInfo: FFX_RESOURCE_USAGE_UAV, FFX_SURFACE_FORMAT_R32G32B32A32_FLOAT, FFX_RESOURCE_FLAGS_NONE
-            FrameInfo = new RenderTexture(1, 1, 0, GraphicsFormat.R32G32B32A32_SFloat) { name = "FSR3UPSCALER_FrameInfo", enableRandomWrite = true };
-            FrameInfo.Create();
+            CreateDoubleBufferedResource(FrameInfo, "FSR3UPSCALER_FrameInfo", Vector2Int.one, GraphicsFormat.R32G32B32A32_SFloat);
 
             // Resources FSR3UPSCALER_Accumulation1/2: FFX_RESOURCE_USAGE_RENDERTARGET | FFX_RESOURCE_USAGE_UAV, FFX_SURFACE_FORMAT_R8_UNORM, FFX_RESOURCE_FLAGS_NONE
             CreateDoubleBufferedResource(Accumulation, "FSR3UPSCALER_Accumulation", maxRenderSize, GraphicsFormat.R8_UNorm);
@@ -190,8 +189,8 @@ namespace FidelityFX.FSR3
             DestroyResource(InternalUpscaled);
             DestroyResource(Luma);
             DestroyResource(Accumulation);
+            DestroyResource(FrameInfo);
             
-            DestroyResource(ref FrameInfo);
             DestroyResource(ref ReconstructedPrevNearestDepth);
             DestroyResource(ref DilatedDepth);
             DestroyResource(ref DilatedVelocity);

Shaders/shaders/ffx_fsr3upscaler_luma_pyramid_pass.hlsl

@@ -22,6 +22,7 @@
 
 #define FSR3UPSCALER_BIND_SRV_CURRENT_LUMA                    0
 #define FSR3UPSCALER_BIND_SRV_FARTHEST_DEPTH                  1
+#define FSR3UPSCALER_BIND_SRV_FRAME_INFO                      2
 
 #define FSR3UPSCALER_BIND_UAV_SPD_GLOBAL_ATOMIC               0
 #define FSR3UPSCALER_BIND_UAV_FRAME_INFO                      1

Shaders/shaders/fsr3upscaler/ffx_fsr3upscaler_luma_pyramid.h

@@ -20,7 +20,7 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 
-FFX_GROUPSHARED FfxUInt32 spdCounter;
+FFX_GROUPSHARED FfxUInt32 spdCounter = 0u;
 
 void SpdIncreaseAtomicCounter(FfxUInt32 slice)
 {
@@ -95,7 +95,7 @@ void SpdStore(FfxInt32x2 pix, FfxFloat32x4 outValue, FfxUInt32 index, FfxUInt32
 
         if (all(FFX_EQUAL(pix, FfxInt32x2(0, 0))))
         {
-            FfxFloat32x4 frameInfo          = LoadFrameInfo();
+            FfxFloat32x4 frameInfo          = FrameInfo();
             const FfxFloat32 fSceneAvgLuma  = outValue[LUMA];
             const FfxFloat32 fPrevLogLuma   = frameInfo[FRAME_INFO_LOG_LUMA];
             FfxFloat32 fLogLuma             = outValue[LOG_LUMA];