ZzSprite/ZzSprite.js at master · KilledByAPixel/ZzSprite · GitHub

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// ZzSprite - Tiny Sprite Generator - Frank Force 2020 - MIT License

'use strict';

// ==ClosureCompiler==
// @compilation_level ADVANCED_OPTIMIZATIONS
// @language_out ECMASCRIPT_2019
// @js_externs ZzSprite
// ==/ClosureCompiler==

function ZzSprite(context, x=0, y=0, seed=1, size=16, mode=0, mutateSeed=0, colorSeed=0)
{
    function Random(max=1, min=0)
    {
        randomSeed ^= randomSeed << 13;
        randomSeed ^= randomSeed >>> 17;
        return (Math.abs(randomSeed ^= randomSeed << 5) % 1e9 / 1e9)*(max-min) + min;
    }

    // random chance to flip drawing axis
    let randomSeed = seed;
    const flipAxis = Random() < .5;
    const w =  flipAxis ? size-3 : size/2 - 1 |0;
    const h = !flipAxis ? size-3 : size/2 - 1 |0;

    // apply mutations
    randomSeed += mutateSeed + 1e8;
    const spriteSize = size * Random(.9, .6);
    const density = Random(1, .9);
    const doubleCenter = Random() < .5;
    const yBias = Random(.1, -.1);
    const colorRand = (mode==1 ? .08 : .04);

    // recenter
    x += size/2 | 0;
    y += 2 | 0;

    function DrawSpriteInternal(x, y, outline)
    {
        // draw each pixel
        randomSeed = seed;
        const passCount = mode == 3 ? 3: 1
        for(let pass=0; pass < passCount; ++pass)
        for(let k=0; k < w*h; ++k)
        {
            const i = flipAxis  ? k/w|0 : k%w;
            const j = !flipAxis ? k/w|0 : k%w;

            // pick new random color using color seed
            const saveSeed = randomSeed;
            randomSeed += colorSeed + 1e9;
            const r = Random(360)|0;
            let newColor = `hsl(${ r },${ Random(200,0)|0 }%,${ Random(100,20)|0 }%)`;
            if (outline || mode == 3)
                newColor = '#000';
            else if (mode == 1)
                newColor = r%3? r%3==1 ? '#444' : '#999' : '#fff';
            else if (mode == 2)
                newColor = `#fff`;
            if (!k || Random() < colorRand)
                context.fillStyle = newColor;
            randomSeed = saveSeed;

            // check if pixel should be drawn
            const isHole = Random() > density;
            if (Random(spriteSize/2)**2 > i*i + (j-(1-2*yBias)*h/2)**2 && !isHole)
            {
                const o = !!outline;
                context.fillRect(x+i-o-doubleCenter, y+j-o, 1+2*o, 1+2*o);
                context.fillRect(x-i-o, y+j-o, 1+2*o, 1+2*o);
            }
        }
    }

    // outline then fill
    if (mode != 3)
        DrawSpriteInternal(x, y, 1);
    DrawSpriteInternal(x, y);
}