slang-shaders/nes_raw_palette/shaders/gtu-famicom/DAC.slang

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#version 450
layout(std140, set = 0, binding = 0) uniform UBO
{
mat4 MVP;
vec4 OutputSize;
vec4 OriginalSize;
vec4 SourceSize;
uint FrameCount;
} global;
////////////////////////////////////////////////////////
// GTU-famicom version 0.50
// Author: aliaspider - aliaspider@gmail.com
// License: GPLv3
////////////////////////////////////////////////////////
#define TO_INT2(X) int(floor(((X) * 3.0) + 0.5))
#define TO_INT3(X) int(floor(((X) * 7.0) + 0.5))
#define TO_INT4(X) int(floor(((X) * 15.0) + 0.5))
bool InColorp (int p, int color)
{
return ((color + p) % 12 < 6);
}
float NTSCsignal(int emphasis, int level, int color, int p)
{
float black = .518;
float white = 1.962;
float attenuation = 0.746;
const float levels[8] = float[] ( 0.350 , 0.518, 0.962, 1.550,
1.094f, 1.506, 1.962, 1.962);
if (color > 13)
level = 1;
float low = levels[0 + level];
float high = levels[4 + level];
if (color == 0)
low = high;
if (color > 12)
high = low;
float signal = InColorp(p, color) ? high : low;
if ((bool(emphasis & 1) && InColorp(p, 0)) ||
(bool(emphasis & 2) && InColorp(p, 4)) ||
(bool(emphasis & 4) && InColorp(p, 8)))
{
signal = signal * attenuation;
}
signal = (signal - black) / (white - black);
return signal;
}
#pragma stage vertex
layout(location = 0) in vec4 Position;
layout(location = 1) in vec2 TexCoord;
layout(location = 0) out vec2 vTexCoord;
layout(location = 1) out float colorPhase;
void main()
{
gl_Position = global.MVP * Position;
vTexCoord = TexCoord;
vec2 pos = (vTexCoord.xy*global.OutputSize.xy) - 0.5;
colorPhase = 8.0001 + pos.x + pos.y * 4.0001 + global.FrameCount * 4.0001;
}
#pragma stage fragment
layout(location = 0) in vec2 vTexCoord;
layout(location = 1) in float colorPhase;
layout(location = 0) out vec4 FragColor;
layout(set = 0, binding = 2) uniform sampler2D Source;
void main()
{
vec4 c = texture(Source, vTexCoord.xy);
int color = TO_INT4(c.x);
int level = TO_INT2(c.y);
int emphasis = TO_INT3(c.z);
float signal = NTSCsignal(emphasis, level, color, int(colorPhase + 0.5));
FragColor = vec4(signal);
}