69 lines
1.7 KiB
GLSL
69 lines
1.7 KiB
GLSL
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#include "/var/signal.glsl"
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#define signal 0 // [0 1 2]
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#define wire 0 // [0 1]
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float luminance(vec3 color) {
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return dot(color, vec3(0.299, 0.587, 0.114));
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}
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vec3 ntsc(vec3 color) {
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// convert to YIQ
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float y = luminance(color);
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float i = dot(color, vec3(0.596, -.274, -.322));
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float q = dot(color, vec3(0.211, -.523, 0.312));
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// faux ntsc signal
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float carrier = 6.283 * 3.570 * gl_FragCoord.x; // 2π * 3.57MHz * x
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float phase = sin(carrier) * i + cos(carrier) * q;
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float quad = cos(carrier) * i - sin(carrier) * q;
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// decode faux signal
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#if wire == WIRE_COMPOSITE
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float composite = phase + (y * 5.500); // p + (y * 5.5MHz)
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y = round(composite * 5.500) / 30.250;
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phase = composite - quad - (y * 5.500);
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quad = composite - phase - (y * 5.500);
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#endif
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i = quad * cos(carrier);
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q = phase * sin(carrier);
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// convert back to RGB
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vec3 yiqColor = vec3(y, i, q);
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float r = dot(yiqColor, vec3(1, 0.956, 0.619));
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float g = dot(yiqColor, vec3(1, -.272, -.674));
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float b = dot(yiqColor, vec3(1, -1.106, 1.703));
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return vec3(r, g, b).rgb;
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}
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vec3 pal(vec3 color) {
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// convert to YUV
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float y = luminance(color);
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float u = 0.492 * (color.b - y);
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float v = 0.877 * (color.r - y);
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// faux pal signal
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float carrier = 6.283 * 4.434;
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float phase = sin(carrier) * u - cos(carrier) * v;
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float quad = cos(carrier) * u - sin(carrier) * v;
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// decode faux signal
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#if wire == WIRE_COMPOSITE
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float composite = y + phase;
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#endif
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u = quad * cos(carrier);
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v = phase * sin(carrier);
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// convert back to RGB
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vec3 yuvColor = vec3(y, u, v);
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float r = y + (1.140 * v);
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float g = y - (0.395 * u) - (0.581 * v);
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float b = y + (2.033 * u);
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return vec3(r, g, b).rgb;
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}
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