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// Fast and easy way to combine (additive mode) two RGBA colors with JavaScript. | |
// [red, green, blue, alpha] based on these maximul values [255, 255, 255, 1]. | |
var base = [69, 109, 160, 1]; | |
var added = [61, 47, 82, 0.8]; | |
var mix = []; | |
mix[3] = 1 - (1 - added[3]) * (1 - base[3]); // alpha | |
mix[0] = Math.round((added[0] * added[3] / mix[3]) + (base[0] * base[3] * (1 - added[3]) / mix[3])); // red | |
mix[1] = Math.round((added[1] * added[3] / mix[3]) + (base[1] * base[3] * (1 - added[3]) / mix[3])); // green | |
mix[2] = Math.round((added[2] * added[3] / mix[3]) + (base[2] * base[3] * (1 - added[3]) / mix[3])); // blue |