let inks = []

function setup() {

  createCanvas(400, 400);

  colorMode(HSB, 255)

  background(220);

}

​

let vol = 1

​

function mousePressed() {

  if (mouseIsPressed) {

    vol = vol + 10

    setTimeout(mousePressed, 0.25)

  } else {

    inks.push( new InkSpot(mouseX, mouseY, color(150, 255, 200, 255), min(vol, 10000)))

    vol = 1

  }

}

​

​

​

​

function draw() {

    for (let ink of inks) {

        ink.draw()

        ink.spread()

​

    }

}

​

​

class InkPoint{

  constructor(x, y, pigment){

    this.x = x

    this.y = y

    this.pigment = pigment

  }

  draw(){

    stroke(this.pigment)

    point(this.x, this.y)

  }

  getNeighbors(){

    let x = this.x

    let y = this.y

    return [

      [x, y+1],

      [x, y-1],

      [x+1, y],

      [x-1, y]]

  }

  getNeighbors8(){

    let x = this.x

    let y = this.y

    return [

      [x, y+1],

      [x, y-1],

      [x+1, y],

      [x-1, y],

      [x+1,y+1],

      [x-1,y-1],

      [x+1,y-1],

      [x-1,y+1],

    ]

  }

}

​

class InkSpot{

  constructor(x, y, pigment, volume){

​

    this.volume = volume

    this.pigment = pigment

    this.points = new Map()

    this.undrawn_points = new Map()

    this.undrawn_points.set(str_key(x, y), new InkPoint(x, y, pigment))

  }

  draw(){

    for (let p of this.undrawn_points.values()) {

      p.draw()

      this.points.set(str_key(p.x, p.y), p)

    }

    this.undrawn_points = new Map()    

  }

  spread(){

    if (this.volume > 0) {

      let values = Array.from(this.points.values())

      for (let p of values) {

        let nbrs = p.getNeighbors8()

        for (let n of nbrs) {

          let x = n[0]

          let y = n[1]

          if (this.volume <= 0) break

          if (!this.points.has(str_key(x, y)) && (random(1.0) > 0.85)) {

            this.volume--

            this.undrawn_points.set(str_key(x, y), new InkPoint(x, y, decay(p.pigment)))

          }

        }

      }

    } else {

      self.points = new Map()

    }

  }

​

}

​

function decay(pigment) {

  let h = hue(pigment)

  let s = saturation(pigment)

  let b = brightness(pigment)

  let a = alpha(pigment)

  return color(h, s, b, a * random(0.8, 1.0))

}

​

function str_key(x, y) {

  return str(x) + ',' + str(y)

}

​