var M = Math,
    random = M.random,
    canvas = document.getElementById('c'),
    ctx = canvas.getContext('2d'),
    population = [],
    env = random()*(1<<24)<<0,
    subject,
    popsize=64,
    cols=8,
    cell=32,
    size=(cols+2)*cell,
    r,g,b,
    r_ = (env&0xff0000)>>16,
    g_ = (env&0xff00)>>8,
    b_ = env&0xff,
    fitness,
    i;
canvas.width = size;
canvas.height = size;
ctx.shadowBlur = 10;
for(i=0; i<popsize; i++) {
    population.push(random()*(1<<24)<<0)
}
function color(s) {
    s=s.toString(16);
    while(s.length<6) s='0'+s;
    return '#'+s;
}
document.body.style.background=color(env);
setInterval((function() {
    ctx.clearRect(0,0,size,size);
    for(i=0;i<popsize;i++){
        subject=population[i];
        r = r_-((subject&0xff0000)>>16);
        g = g_-((subject&0xff00)>>8);
        b = b_-(subject&0xff);
        fitness=M.sqrt(r*r+g*g+b*b)/443;
        if(random()<fitness){
            // subject died, breed new one
            subject = population[i] = (
                // breed
                ((population[random()*popsize<<0]&0xfff000)|
                (population[random()*popsize<<0]&0xfff))
                // Mutate
                ^(1<<(random()*24<<0))
            );
        }
        ctx.fillStyle = color(subject);
        ctx.fillRect(1+(i%cols)<<5, 1+(i/cols)<<5, cell, cell);
    }
}), 100);