28 lines
804 B
GLSL
28 lines
804 B
GLSL
/**
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* Converts an RGB color to HSB (hue, saturation, brightness)
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* HSB <-> RGB conversion with minimal branching: {@link http://lolengine.net/blog/2013/07/27/rgb-to-hsv-in-glsl}
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*
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* @name czm_RGBToHSB
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* @glslFunction
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*
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* @param {vec3} rgb The color in RGB.
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*
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* @returns {vec3} The color in HSB.
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*
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* @example
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* vec3 hsb = czm_RGBToHSB(rgb);
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* hsb.z *= 0.1;
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* rgb = czm_HSBToRGB(hsb);
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*/
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const vec4 K_RGB2HSB = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
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vec3 czm_RGBToHSB(vec3 rgb)
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{
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vec4 p = mix(vec4(rgb.bg, K_RGB2HSB.wz), vec4(rgb.gb, K_RGB2HSB.xy), step(rgb.b, rgb.g));
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vec4 q = mix(vec4(p.xyw, rgb.r), vec4(rgb.r, p.yzx), step(p.x, rgb.r));
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float d = q.x - min(q.w, q.y);
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return vec3(abs(q.z + (q.w - q.y) / (6.0 * d + czm_epsilon7)), d / (q.x + czm_epsilon7), q.x);
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}
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