Troy James Sobotka
f1ff4a9047
While still not colour managed, and grossly assuming REC.709 display referred buffers, the effect as it currently stands can be improved to use the proper coefficients for REC.709, as opposed to legacy REC.601. Ideally there'd be a flag somewhere to flip between the two coefficient sets.
70 lines
2.2 KiB
GLSL
70 lines
2.2 KiB
GLSL
/*a fast implementation of the chromakey program
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(c) 2008 Edward Cannon (adapted to GLSL by Olive Team)
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feel free to use or modify at will*/
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/*the follwing three functions convert RGB into YCbCr in the same manner as in JPEG images*/
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uniform sampler2D tex;
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varying vec2 vTexCoord;
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uniform vec3 key_color;
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uniform float tola;
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uniform float tolb;
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uniform bool opt;
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uniform int mode;
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// This isn’t colour managed and is a huge mess, but in the
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// short term, using correct weights will give significantly
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// more ideal results. The correct weights for REC.709 are
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// 0.2126 R, 0.7152 G, and 0.722 B. Easy change.
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// The coefficients for YCbCr are calculated off of the
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// REC.709 values.
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return (0.2126*c.r + 0.7152*c.g + 0.0722*c.b);
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}
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float rgb2cb (vec3 c) {
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/*a utility function to convert colors in RGB into YCbCr*/
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return (0.5 + -0.1145721061*c.r - 0.3854278939*c.g + 0.5*c.b);
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}
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float rgb2cr (vec3 c) {
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/*a utility function to convert colors in RGB into YCbCr*/
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return (0.5 + 0.5*c.r - 0.4541529083*c.g - 0.0458470917*c.b);
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}
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float colorclose(float Cb_p,float Cr_p,float Cb_key,float Cr_key,float tola,float tolb) {
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/*decides if a color is close to the specified hue*/
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float temp = sqrt(((Cb_key-Cb_p)*(Cb_key-Cb_p))+((Cr_key-Cr_p)*(Cr_key-Cr_p)));
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if (temp < tola) {return (0.0);}
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if (temp < tolb) {return ((temp-tola)/(tolb-tola));}
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return (1.0);
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}
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void main(void) {
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float cb_key = rgb2cb(key_color);
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float cr_key = rgb2cr(key_color);
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vec4 texture_color = texture2D(tex, vTexCoord);
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float cb = rgb2cb(texture_color.rgb);
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float cr = rgb2cr(texture_color.rgb);
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float mask = colorclose(cb, cr, cb_key, cr_key, (tola/100.0), (tolb/100.0));
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if (mode == 0) { // composite
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//float submask = 1.0-mask;
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float submask = 0.0;
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texture_color.r = max(texture_color.r - submask*key_color.r, 0.0) + submask;
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texture_color.g = max(texture_color.g - submask*key_color.g, 0.0) + submask;
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texture_color.b = max(texture_color.b - submask*key_color.b, 0.0) + submask;
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texture_color.a *= mask;
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// premultiply
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texture_color.rgb *= texture_color.a;
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} else if (mode == 1) { // alpha
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texture_color.rgb = vec3(mask);
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} else if (mode == 2) { // original
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}
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gl_FragColor = texture_color;
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}
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