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July 31, 2015 09:55
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Combine two RGBA colors with JavaScript
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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 | |
| // Will return [63, 59, 98, 1] |
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Hi there. I made the Swift implementation. Maybe it will be useful for somebody.
https://gist.github.com/ilia3546/a90fcdc208b49f69be95ecd854544d73