las vegas lights

Adapted from a CFDG program
by mattpace, August 22th, 2006
contextfreeart.org/gallery2/#design/393

Created by ge1doot on 2019/2/10
51
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// You can find the Turtle API reference here: https://turtletoy.net/syntax
Canvas.setpenopacity(0.75);
// Global code will be evaluated once.
const turtle = new Turtle();
turtle.penup();
/////////////////////////////////////////////////////
const Mat2D = class {
    constructor (m) { 
        this.m = m;
    }
    rotate (v) {
    	const rad = Math.PI * v / 180;
    	const cos = Math.cos(rad);
    	const sin = Math.sin(rad);
    	return new Mat2D([
    		cos * this.m[0] + sin * this.m[2],
    		cos * this.m[1] + sin * this.m[3],
    		cos * this.m[2] - sin * this.m[0],
    		cos * this.m[3] - sin * this.m[1],
    		this.m[4],
    		this.m[5]
    	]);
    } 
    translate (x, y = 0) {
    	return new Mat2D([
    		this.m[0],
    		this.m[1],
    		this.m[2],
    		this.m[3],
    		this.m[4] + x * this.m[0] + y * this.m[2],
    		this.m[5] + x * this.m[1] + y * this.m[3]
    	]);
    }
    scale (x = 1, y = x) {
        return new Mat2D([
    		this.m[0] * x,
    		this.m[1] * x,
    		this.m[2] * y,
    		this.m[3] * y,
    		this.m[4],
    		this.m[5]
    	]);
	}
	size () {
        const x = this.m[0] * this.m[0] + this.m[1] * this.m[1];
        const y = this.m[2] * this.m[2] + this.m[3] * this.m[3];
        return Math.sqrt(Math.max(x, y));
	}
    transform (x, y) {
		const m0 = this.m[0] * zoom;
		const m1 = this.m[1] * zoom;
		const m2 = this.m[2] * zoom;
		const m3 = this.m[3] * zoom;
		const m4 = this.m[4] * zoom - ox;
		const m5 = this.m[5] * zoom - oy;
		return [
            m0 * x + m2 * y + m4, 
            m1 * x + m3 * y + m5
		];
	}
	boundingBox (box) {
        const p0 = this.transform(0, 0);
        const p1 = this.transform(0.5, 0);
        const p2 = this.transform(0.5, 0.5);
        const p3 = this.transform(0, 0.5);
        const minx = Math.min(p0[0], p1[0], p2[0], p3[0]);
        const maxx = Math.max(p0[0], p1[0], p2[0], p3[0]);
        const miny = Math.min(p0[1], p1[1], p2[1], p3[1]);
        const maxy = Math.max(p0[1], p1[1], p2[1], p3[1]);
    	if (minx < box[0]) box[0] = minx; else if (maxx > box[2]) box[2] = maxx;
    	if (miny < box[1]) box[1] = miny; else if (maxy > box[3]) box[3] = maxy;
    }
};
///////////////////////////////////////////////////////
const shapes =  [];
let zoom = 1, ox = 0, oy = 0;
const box = [0, 0, 0, 0];
const rect = m => {
	m.boundingBox(box);
	shapes.push(m);
};
const draw = shape => {
    // strokeRect
    turtle.goto(shape.transform(-0.5, -0.5));
    turtle.down();
    turtle.goto(shape.transform( 0.5, -0.5));
    turtle.goto(shape.transform( 0.5,  0.5));
    turtle.goto(shape.transform(-0.5,  0.5));
    turtle.goto(shape.transform(-0.5, -0.5));
    turtle.up();
}
const scale = (margin = 0.95) => {
	zoom = Math.min(
		margin * 200 / (box[2] - box[0]),
		margin * 200 / (box[3] - box[1])
	);
	ox = (box[0] + box[2]) * 0.5 * zoom;
	oy = (box[3] + box[1]) * 0.5 * zoom;
};
//
//
//
//
/////////////////////////CFDG ///////////////////////////
const minSize = 0.1;
const RUN = m => {
    if (m.size() < minSize) return;
    const r = Math.random() * 50;
    let weight = 0;
    switch (true) {
        //even more rarely, split off...
        case r <= (weight += 0.5):
            SHAPE(m);
            RUN(m);
            return SHARPRIGHT(m);
        case r <= (weight += 0.5):
            SHAPE(m);
            RUN(m);
            return SHARPLEFT(m);
        case r <= (weight += 0.5):
            SHAPE(m);
            RUN(m);
            return RUNRIGHT(m);
        case r <= (weight += 0.5):
            SHAPE(m);
            RUN(m);
            return RUNLEFT(m);
        //every once in awhile, start a turn
        case r <= (weight += 2):
            SHAPE(m);
            return SHARPRIGHT(m.translate(0, 4).rotate(-10).scale(0.997));
        case r <= (weight += 2):
            SHAPE(m);
            return SHARPLEFT(m.translate(0, 4).rotate(10).scale(0.997));
        case r <= (weight += 2):
            SHAPE(m);
            return RUNRIGHT(m.translate(0, 4).rotate(-10).scale(0.997));
        case r <= (weight += 2):
            SHAPE(m);
            return RUNLEFT(m.translate(0, 4).rotate(10).scale(0.997));
        default:
            SHAPE(m);
            return RUN(m.translate(0, 4).scale(0.997));
    }
}
//the turns
const RUNLEFT = m => {
    if (m.size() < minSize) return;
    const r = Math.random() * 201;
    let weight = 0;
    switch (true) {
        case r <= (weight += 1):
            SHAPE(m);
            return RUN(m.translate(0, 4).scale(0.997));
        default:
            SHAPE(m);
            return RUN(m.translate(0, 4).rotate(10).scale(0.997));
    }
}
const RUNRIGHT = m => {
    if (m.size() < minSize) return;
    const r = Math.random() * 201;
    let weight = 0;
    switch (true) {
        case r <= (weight += 1):
            SHAPE(m);
            return RUN(m.translate(0, 4).scale(0.997));
        default:
            SHAPE(m);
            return  RUN(m.translate(0, 4).rotate(-10).scale(0.997));
    }
}
const SHARPLEFT = m => {
    if (m.size() < minSize) return;
    const r = Math.random() * 201;
    let weight = 0;
    switch (true) {
        case r <= (weight += 1):
            SHAPE(m);
            return RUN(m.translate(0, 4).scale(0.997));
        default:
            SHAPE(m);
            return SHARPLEFT(m.translate(0, 4).rotate(20).scale(0.997));
    }
}
const SHARPRIGHT = m => {
    if (m.size() < minSize) return;
    const r = Math.random() * 201;
    let weight = 0;
    switch (true) {
        case r <= (weight += 1):
            SHAPE(m);
            return RUN(m.translate(0, 4).scale(0.997));
        default:
            SHAPE(m);
            return SHARPRIGHT(m.translate(0, 4).rotate(-20).scale(0.997));
    }
}
const SHAPE = m => {
    rect(m.scale(0.45, 3));
}

/////////////////// render scene //////////////////////////////
//
//
//
//
RUN(new Mat2D([1, 0, 0, -1, 0, 0]));
scale(0.95);

// The walk function will be called until it returns false.
function walk(i) {
	const m = shapes.pop();
	if (!m) return false;
	draw(m);
	return true;
}