slang-shaders/test/nonfunctional/shaders/mame/mame_chroma.slang

#version 450

// license:BSD-3-Clause
// copyright-holders:W. M. Martinez
//-----------------------------------------------------------------------------
// Phosphor Chromaticity to sRGB Transform Effect
//-----------------------------------------------------------------------------

layout(push_constant) uniform Push
{
	vec4 SourceSize;
	vec4 OriginalSize;
	vec4 OutputSize;
	uint FrameCount;
} params;

layout(std140, set = 0, binding = 0) uniform UBO
{
	mat4 MVP;
} global;

#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;

#define DiffuseSampler Source
#define mul(a,b) (b*a)

const vec3 YGain = vec3(0.2126, 0.7152, 0.0722);
const vec2 ChromaA = vec2(0.630, 0.340);
const vec2 ChromaB = vec2(0.310, 0.595);
const vec2 ChromaC = vec2(0.155, 0.070);

const mat3 XYZ_TO_sRGB = mat3(
	 3.2406, -1.5372, -0.4986,
        -0.9689,  1.8758,  0.0415,
	 0.0557, -0.2040,  1.0570);

void main()
{
	vec4 cin = texture(DiffuseSampler, vTexCoord);
	vec4 cout = vec4(0.0, 0.0, 0.0, cin.a);
	mat3x2 xy = { ChromaA, ChromaB, ChromaC };

	for (int i = 0; i < 3; ++i) {
		float Y = YGain[i] * cin[i];
		float X = xy[i].x * (Y / xy[i].y);
		float Z = (1.0 - xy[i].x - xy[i].y) * (Y / xy[i].y);
		cout.rgb += mul(XYZ_TO_sRGB, vec3(X, Y, Z));
	}
	FragColor = cout;
}