​

let bg;

​

function preload() {

  bg = loadImage("paper.jpeg");

}

​

function setup() {

  createCanvas(600, 600);

  const v = [];

  const n = 4;

  for(let i = 0; i < n; i ++) {

    let a = i * (TAU/n);

    v.push(createVector(width/2 + cos(a) * 200, height/2 + sin(a) * 200));

  }

  poly = new Poly(v);

  noLoop();

}

​

function draw() {

  background(255);

  tint(255, 150);

  image(bg, 0, 0, width, height);

  //poly.draw();

  waterColour(poly, color(255, 100, 0));

}

​

class Poly {

  constructor(vertices, modifiers) {

    this.vertices = vertices;

    if(!modifiers) {

      modifiers = [];

      for(let i = 0; i < vertices.length; i ++) {

        modifiers.push(random(0.1, 0.8));

      }

    }

    this.modifiers = modifiers;

  }

  grow() {

    const grownVerts = [];

    const grownMods = [];

    for(let i = 0; i < this.vertices.length; i ++) {

      const j = (i + 1) % this.vertices.length;

      const v1 = this.vertices[i];

      const v2 = this.vertices[j];

      const mod = this.modifiers[i];

      const chmod = m => {

        return m + (rand() - 0.5) * 0.1;

      }

      grownVerts.push(v1);

      grownMods.push(chmod(mod));

      const segment = p5.Vector.sub(v2, v1);

      const len = segment.mag();

      segment.mult(rand());

      const v = p5.Vector.add(segment, v1);

      segment.rotate(-PI/2 + (rand()-0.5) * PI/4);

      segment.setMag(rand() * len/2 * mod);

      v.add(segment);

      grownVerts.push(v);

      grownMods.push(chmod(mod));

    }

    return new Poly(grownVerts, grownMods);

  }

  dup() {

    return new Poly(Array.from(this.vertices), Array.from(this.modifiers));

  }

  draw() {

    beginShape();

    for(let v of this.vertices) {

      vertex(v.x, v.y);

    }

    endShape(CLOSE);

  }

}

​

function waterColour(poly, colour) {

  const numLayers = 50;

  fill(red(colour), green(colour), blue(colour), 255/(2 * numLayers));

  noStroke();

  poly = poly.grow().grow();

  for(let i = 0; i < numLayers; i ++) {

    if(i == int(numLayers/3) || i == int(2 * numLayers/3)) {

      poly = poly.grow().grow();

    }

    poly.grow().draw();

  }  

}

​

function rand() {

  return distribute(random(1));

}

​

function distribute(x) {

  return pow((x - 0.5) * 1.58740105, 3) + 0.5;

}

​

​

​

​

​