cvpixelbuffer promise sRGB support improvements

MetalPetal · Feb 11, 2019 · ade9086 · ade9086
1 parent 1eede3d
commit ade9086
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Showing 3 changed files with 27 additions and 29 deletions.
diff --git a/Frameworks/MetalPetal/MTICVPixelBufferPromise.m b/Frameworks/MetalPetal/MTICVPixelBufferPromise.m
@@ -305,7 +305,7 @@ - (MTIImagePromiseRenderTarget *)resolveWithContext_MTI:(MTIImageRenderingContex
                 }
 
                 // Render Pipeline
-                MTLPixelFormat pixelFormat = self.sRGB ? MTLPixelFormatBGRA8Unorm_sRGB : MTLPixelFormatBGRA8Unorm;
+                MTLPixelFormat pixelFormat = MTLPixelFormatBGRA8Unorm;
                 MTITextureDescriptor *textureDescriptor = [MTITextureDescriptor texture2DDescriptorWithPixelFormat:pixelFormat width:CVPixelBufferGetWidth(_pixelBuffer) height:CVPixelBufferGetHeight(_pixelBuffer) usage:MTLTextureUsageShaderRead | MTLTextureUsageRenderTarget];
                 MTIImagePromiseRenderTarget *renderTarget = [renderingContext.context newRenderTargetWithResuableTextureDescriptor:textureDescriptor error:&error];
                 if (error) {
@@ -334,6 +334,8 @@ - (MTIImagePromiseRenderTarget *)resolveWithContext_MTI:(MTIImageRenderingContex
                 [renderCommandEncoder setFragmentTexture:cvMetalTextureY.texture atIndex:0];
                 [renderCommandEncoder setFragmentTexture:cvMetalTextureCbCr.texture atIndex:1];
                 [renderCommandEncoder setFragmentBytes:preferredConversion length:sizeof(MTIYUVColorConversion) atIndex:0];
+                bool convertToLinearRGB = self.sRGB;
+                [renderCommandEncoder setFragmentBytes:&convertToLinearRGB length:sizeof(convertToLinearRGB) atIndex:1];
                 [renderCommandEncoder drawPrimitives:MTLPrimitiveTypeTriangleStrip vertexStart:0 vertexCount:4 instanceCount:1];
                 [renderCommandEncoder endEncoding];
 

diff --git a/Frameworks/MetalPetal/Shaders/ColorConversionShaders.metal b/Frameworks/MetalPetal/Shaders/ColorConversionShaders.metal
@@ -8,6 +8,7 @@
 
 #include <metal_stdlib>
 #include <simd/simd.h>
+#include "MTIShaderLib.h"
 
 using namespace metal;
 
@@ -37,15 +38,15 @@ namespace metalpetal {
             return out;
         }
 
-        fragment half4 colorConversionFragment(Varyings in [[ stage_in ]],
+        fragment float4 colorConversionFragment(Varyings in [[ stage_in ]],
                                                texture2d<float, access::sample> yTexture [[ texture(0) ]],
                                                texture2d<float, access::sample> cbcrTexture [[ texture(1) ]],
-                                               constant ColorConversion &colorConversion [[ buffer(0) ]]) {
-
+                                               constant ColorConversion &colorConversion [[ buffer(0) ]],
+                                               constant bool &convertToLinearRGB [[ buffer(1) ]]) {
             constexpr sampler s(address::clamp_to_edge, filter::linear);
             float3 ycbcr = float3(yTexture.sample(s, in.texcoord).r, cbcrTexture.sample(s, in.texcoord).rg);
             float3 rgb = colorConversion.matrix * (ycbcr + colorConversion.offset);
-            return half4(half3(rgb), 1.0);
+            return float4(float3(convertToLinearRGB ? sRGBToLinear(rgb) : rgb), 1.0);
         }
 
         kernel void colorConversion(uint2 gid [[ thread_position_in_grid ]],

diff --git a/Frameworks/MetalPetal/Shaders/MTIShaderLib.h b/Frameworks/MetalPetal/Shaders/MTIShaderLib.h
@@ -60,14 +60,27 @@ namespace metalpetal {
     } VertexOut;
 
     // GLSL mod func for metal
-    template <typename T, typename _E = typename enable_if<is_same<float, typename make_scalar<T>::type>::value>::type>
+    template <typename T, typename _E = typename enable_if<is_floating_point<typename make_scalar<T>::type>::value>::type>
     METAL_FUNC T mod(T x, T y) {
         return x - y * floor(x/y);
     }
 
-    template <typename T, typename _E = typename enable_if<is_same<float, typename make_scalar<T>::type>::value>::type>
-    METAL_FUNC T sRGBToLinear(T x) {
-        return sign(x)*mix(abs(x)*0.077399380804954, pow(abs(x)*0.947867298578199 + 0.052132701421801, 2.4), step(0.04045, abs(x)));
+    template <typename T, typename _E = typename enable_if<is_floating_point<T>::value>::type>
+    METAL_FUNC T sRGBToLinear(T c) {
+        return (c <= 0.04045f) ? c / 12.92f : powr((c + 0.055f) / 1.055f, 2.4f);
+    }
+
+    METAL_FUNC float3 sRGBToLinear(float3 c) {
+        return float3(sRGBToLinear(c.r), sRGBToLinear(c.g), sRGBToLinear(c.b));
+    }
+
+    template <typename T, typename _E = typename enable_if<is_floating_point<T>::value>::type>
+    METAL_FUNC T linearToSRGB(T c) {
+        return (c < 0.0031308f) ? (12.92f * c) : (1.055f * powr(c, 1.f/2.4f) - 0.055f);
+    }
+
+    METAL_FUNC float3 linearToSRGB(float3 c) {
+        return float3(linearToSRGB(c.r), linearToSRGB(c.g), linearToSRGB(c.b));
     }
 
     METAL_FUNC float4 unpremultiply(float4 s) {
@@ -78,26 +91,8 @@ namespace metalpetal {
         return float4(s.rgb * s.a, s.a);
     }
 
-    METAL_FUNC float hue2rgb(float p, float q, float t){
-        if(t < 0.0) {
-            t += 1.0;
-        }
-        if(t > 1.0) {
-            t -= 1.0;
-        }
-        if(t < 1.0/6.0) {
-            return p + (q - p) * 6.0 * t;
-        }
-        if(t < 1.0/2.0) {
-            return q;
-        }
-        if(t < 2.0/3.0) {
-            return p + (q - p) * (2.0/3.0 - t) * 6.0;
-        }
-        return p;
-    }
-
-    METAL_FUNC half hue2rgb(half p, half q, half t){
+    template <typename T, typename _E = typename enable_if<is_floating_point<T>::value>::type>
+    METAL_FUNC T hue2rgb(T p, T q, T t){
         if(t < 0.0) {
             t += 1.0;
         }