obelisk.js/src/utils/ColorGeom.js

JavaScript Library for Building Pixel Isometric Element with HTML5 Canvas

/*jslint node:true*/

'use strict';

var ColorGeom, p;

ColorGeom = function () {
    throw new Error('ColorGeom is a static Class, cannot be instanced.');
};
p = ColorGeom;

// public methods
p.get32 = function (color) {
    return color < 0xFF000000 ? (color + 0xFF000000) : color;
};

p.applyBrightness = function (color, brightness, highlight) {
    var a, r, g, b, y, v, u;

    a = ((color >>> 24) & 0x000000FF);
    r = ((color >>> 16) & 0x000000FF);
    g = ((color >>> 8) & 0x000000FF);
    b = (color & 0x000000FF);

    y = ((r * 313524) >> 20) + ((g * 615514) >> 20) + ((b * 119538) >> 20);
    u = -((155189 * r) >> 20) - ((303038 * g) >> 20) + ((458227 * b) >> 20);
    v = ((644874 * r) >> 20) - ((540016 * g) >> 20) - ((104857 * b) >> 20);

    if (!highlight) {
        y += brightness;
    } else {
        y = 60 + Math.pow(y, 1.2);
    }

    r = y + ((1195376 * v) >> 20);
    g = y - ((408944 * u) >> 20) - ((608174 * v) >> 20);
    b = y + ((2128609 * u) >> 20);

    r = Math.max(0, Math.min(r, 255));
    g = Math.max(0, Math.min(g, 255));
    b = Math.max(0, Math.min(b, 255));

    return (a << 24) | (r << 16) | (g << 8) | b;
};

p.toString = function () {
    return '[ColorGeom]';
};

module.exports = ColorGeom;