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https://github.com/italicsjenga/slang-shaders.git
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add ntsc-xot shader and preset
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hunterk
parent
de73a1a98e
commit
a9455fec40
9
ntsc/ntsc-xot.slangp
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ntsc/ntsc-xot.slangp
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shaders = 2
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shader0 = ../stock.slang
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scale_type_x0 = absolute
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scale_x0 = "640.0"
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shader1 = shaders/ntsc-xot.slang
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scale1 = 1.0
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scale_type1 = source
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228
ntsc/shaders/ntsc-xot.slang
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ntsc/shaders/ntsc-xot.slang
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#version 450
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// NTSC Decoder
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//
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// Decodes composite video signal generated in Buffer A.
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// Move mouse to display the original signal.
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//
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// This is an intensive shader with a lot of sampling and
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// iterated filtering. Reduce filter width N to trade quality
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// for performance. N should be an integer multiple of four,
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// plus one (4n+1). Apologies to owners of melted phones.
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//
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// hunterk made the shader work in RGB instead of just a single
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// channel, though there's probably better ways to do it than
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// just tripling all of the operations. Improvements are welcome!
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//
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// copyright (c) 2017, John Leffingwell
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// license CC BY-SA Attribution-ShareAlike
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// adapted for RetroAch by hunterk from this shadertoy:
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// https://www.shadertoy.com/view/Mdffz7
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layout(push_constant) uniform Push
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{
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vec4 SourceSize;
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vec4 OriginalSize;
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vec4 OutputSize;
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uint FrameCount;
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} params;
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layout(std140, set = 0, binding = 0) uniform UBO
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{
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mat4 MVP;
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} global;
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#pragma stage vertex
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layout(location = 0) in vec4 Position;
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layout(location = 1) in vec2 TexCoord;
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layout(location = 0) out vec2 vTexCoord;
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void main()
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{
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gl_Position = global.MVP * Position;
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vTexCoord = TexCoord;
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}
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#pragma stage fragment
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layout(location = 0) in vec2 vTexCoord;
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layout(location = 0) out vec4 FragColor;
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layout(set = 0, binding = 2) uniform sampler2D Source;
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#define PI 3.14159265358979323846
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#define TAU 6.28318530717958647693
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// TV adjustments
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const float SAT = 1.0; // Saturation / "Color" (normally 1.0)
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const float HUE = 1.0; // Hue / "Tint" (normally 0.0)
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const float BRI = 1.0; // Brightness (normally 1.0)
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// Filter parameters
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const int N = 21; // Filter Width (4n+1)
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const float FC = 0.125; // Frequency Cutoff
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const mat3 YIQ2RGB = mat3(1.000, 1.000, 1.000,
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0.956,-0.272,-1.106,
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0.621,-0.647, 1.703);
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vec3 adjust(vec3 YIQ, float H, float S, float B) {
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mat3 M = mat3( B, 0.0, 0.0,
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0.0, S*cos(H), -sin(H),
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0.0, sin(H), S*cos(H) );
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return M * YIQ;
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}
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float sinc(float n) {
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if (n == 0.0) return 1.0;
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return sin(PI*n) / (PI*n);
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}
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float window_blackman(float n, float N) {
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return 0.42 - 0.5 * cos((2.0*PI*n)/(N-1.0)) + 0.08 * cos((4.0*PI*n)/(N-1.0));
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}
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float pulse(float a, float b, float x) {
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return step(a, x) * step(x, b);
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}
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void main()
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{
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vec2 size = params.SourceSize.xy;
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vec2 uv = vTexCoord.xy;
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// Compute sampling offsets and weights
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float sumR = 0.0;
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float sumG = 0.0;
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float sumB = 0.0;
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vec4 offsetR[N];
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vec4 offsetG[N];
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vec4 offsetB[N];
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// R
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for (int i=0; i<N; i++) {
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float jR = float(i) - (float(N-1)/2.0);
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float kR = sinc( 2.0 * FC * jR) * window_blackman(float(i),float(N));
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offsetR[i] = vec4(jR/size.x, 0.0, kR, -kR);
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sumR += kR;
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}
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// Low-pass filter input signal
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float tapR[N];
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for (int i=0; i<N; i++) {
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offsetR[i].zw /= sumR;
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tapR[i] = pulse(0.0, 1.0, uv.x + offsetR[i].x) * texture(Source, uv + offsetR[i].xy).r;
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}
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offsetR[(N-1)/2].w += 1.0;
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// Extract luma signal
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float lumaR = 0.0;
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for (int i=0; i<N; i++) {
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lumaR += tapR[i] * offsetR[i].z;
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}
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// Extract chroma signal
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float chromaR[N];
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for (int j=0; j<N; j++) {
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chromaR[j] = 0.0;
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for (int i=0; i<N; i++) {
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chromaR[j] += tapR[i+j-(N-1)/2] * offsetR[i].w;
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}
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}
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// G
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for (int i=0; i<N; i++) {
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float jG = float(i) - (float(N-1)/2.0);
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float kG = sinc( 2.0 * FC * jG) * window_blackman(float(i),float(N));
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offsetG[i] = vec4(jG/size.x, 0.0, kG, -kG);
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sumG += kG;
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}
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// Low-pass filter input signal
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float tapG[N];
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for (int i=0; i<N; i++) {
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offsetG[i].zw /= sumG;
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tapG[i] = pulse(0.0, 1.0, uv.x + offsetG[i].x) * texture(Source, uv + offsetG[i].xy).g;
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}
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offsetG[(N-1)/2].w += 1.0;
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// Extract luma signal
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float lumaG = 0.0;
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for (int i=0; i<N; i++) {
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lumaG += tapG[i] * offsetG[i].z;
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}
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// Extract chroma signal
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float chromaG[N];
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for (int j=0; j<N; j++) {
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chromaG[j] = 0.0;
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for (int i=0; i<N; i++) {
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chromaG[j] += tapG[i+j-(N-1)/2] * offsetG[i].w;
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}
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}
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// B
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for (int i=0; i<N; i++) {
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float jB = float(i) - (float(N-1)/2.0);
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float kB = sinc( 2.0 * FC * jB) * window_blackman(float(i),float(N));
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offsetB[i] = vec4(jB/size.x, 0.0, kB, -kB);
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sumB += kB;
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}
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// Low-pass filter input signal
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float tapB[N];
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for (int i=0; i<N; i++) {
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offsetB[i].zw /= sumB;
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tapB[i] = pulse(0.0, 1.0, uv.x + offsetB[i].x) * texture(Source, uv + offsetB[i].xy).b;
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}
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offsetB[(N-1)/2].w += 1.0;
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// Extract luma signal
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float lumaB = 0.0;
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for (int i=0; i<N; i++) {
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lumaB += tapB[i] * offsetB[i].z;
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}
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// Extract chroma signal
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float chromaB[N];
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for (int j=0; j<N; j++) {
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chromaB[j] = 0.0;
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for (int i=0; i<N; i++) {
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chromaB[j] += tapB[i+j-(N-1)/2] * offsetB[i].w;
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}
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}
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// Generate YIQ signal R
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float YR = lumaR;
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float IR = 0.0;
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float QR = 0.0;
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for (int j=0; j<N; j++) {
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float subcarrierR = TAU * 0.25 * size.x * (uv.s + float(j+(N-1)/2)/size.x);
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IR += cos(subcarrierR) * chromaR[j] * offsetR[j].z;
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QR += sin(subcarrierR) * chromaR[j] * offsetR[j].z;
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}
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// Generate YIQ signal G
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float YG = lumaG;
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float IG = 0.0;
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float QG = 0.0;
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for (int j=0; j<N; j++) {
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float subcarrierG = TAU * 0.25 * size.x * (uv.s + float(j+(N-1)/2)/size.x);
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IG += cos(subcarrierG) * chromaG[j] * offsetG[j].z;
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QG += sin(subcarrierG) * chromaG[j] * offsetG[j].z;
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}
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// Generate YIQ signal B
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float YB = lumaB;
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float IB = 0.0;
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float QB = 0.0;
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for (int j=0; j<N; j++) {
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float subcarrierB = TAU * 0.25 * size.x * (uv.s + float(j+(N-1)/2)/size.x);
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IB += cos(subcarrierB) * chromaB[j] * offsetB[j].z;
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QB += sin(subcarrierB) * chromaB[j] * offsetB[j].z;
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}
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// Apply TV adjustments to YIQ signal and convert to RGB
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FragColor.r = (YIQ2RGB * adjust(vec3(YR, IR, QR), HUE, SAT, BRI)).r;
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FragColor.g = (YIQ2RGB * adjust(vec3(YG, IG, QG), HUE, SAT, BRI)).g;
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FragColor.b = (YIQ2RGB * adjust(vec3(YB, IB, QB), HUE, SAT, BRI)).b;
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}
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