Merge pull request #53 from Monroe88/yiq_hue

Add a YIQ Hue adjustment shader

misc/yiq-hue-adjustment.slang

@@ -0,0 +1,53 @@
+#version 450
+
+/* 
+	YIQ Hue Adjustment Shader
+	Ported from https://github.com/AnalyticalGraphicsInc/cesium/blob/master/Source/Shaders/Builtin/Functions/hue.glsl
+*/
+
+layout(push_constant) uniform Push
+{
+	vec4 SourceSize;
+	vec4 OriginalSize;
+	vec4 OutputSize;
+	uint FrameCount;
+	float hue_degrees;
+} params;
+
+layout(std140, set = 0, binding = 0) uniform UBO
+{
+	mat4 MVP;
+} global;
+
+#pragma parameter hue_degrees "Hue" 0.0 -360.0 360.0 1.0
+#define M_PI 3.1415926535897932384626433832795
+
+#include "colorspace-tools.h"
+
+#pragma stage vertex
+layout(location = 0) in vec4 Position;
+layout(location = 1) in vec2 TexCoord;
+layout(location = 0) out vec2 vTexCoord;
+
+void main()
+{
+   gl_Position = global.MVP * Position;
+   vTexCoord = TexCoord;
+}
+
+#pragma stage fragment
+layout(location = 0) in vec2 vTexCoord;
+layout(location = 0) out vec4 FragColor;
+layout(set = 0, binding = 2) uniform sampler2D Source;
+
+void main()
+{
+   vec3 rgb = texture(Source, vTexCoord).rgb;
+   vec3 yiq = RGBtoYIQ(rgb);
+   float hue_radians = params.hue_degrees * (M_PI / 180.0);
+   float hue = atan(yiq.z, yiq.y) + hue_radians;
+   float chroma = sqrt(yiq.z * yiq.z + yiq.y * yiq.y);
+   
+   vec3 color = vec3(yiq.x, chroma * cos(hue), chroma * sin(hue));
+   FragColor = vec4(YIQtoRGB(color).rgb, 1.0);
+}