Noise_in_circles.pde

var particles = []
var colors = ["#3DB2FF","#FFB830","#FF2442","#FF7600","#185ADB","#0A1931","#99154E"]
var n, s, maxR

function setup() {
	createCanvas(windowWidth, windowHeight)
	initCanvas()
}

function draw() {
	translate(width/2, height/2)
	noStroke()
	
	if(s > 1) {
		if(particles.length != 0) {
			for(let i = 0; i < particles.length; i++) {
				var p = particles[i]
				p.show()
				p.move()
				
				if(p.isDead()) particles.splice(i, 1)
			}
		} else {
			s -= 2
			initParticles()
		}
	}
}

function initParticles() {
	var c = colors[int(random(colors.length))]
	
	for(let i = 0; i < n; i++) {
		particles.push(new Particle(maxR, s, c))
	}
}

function initCanvas() {
	background("#FFEDDA")
	smooth()
	particles = []
	n = 150
	s = 20
	maxR = height/2 - height/10
}

function mousePressed() {
	initCanvas()
}

class Particle {
  
  constructor(maxR_, s_, c_) {
    this.s = s_
    this.c = c_
    this.maxR = maxR_
    
    this.life = 100
    
    this.init()
  }
  
  init() {
    this.pos = p5.Vector.random2D()
    this.pos.normalize()
    this.pos.mult(random(2, maxR))

    this.vel = createVector()
  }

  show() {
    fill(this.c)
    ellipse(this.pos.x, this.pos.y, this.s, this.s)
    this.life -= 1
  }
  
  move() {
    var angle = noise(this.pos.x / 400, this.pos.y / 400) * TAU
    
    this.vel.set(cos(angle), sin(angle))
    this.vel.mult(0.3)
    this.pos.add(this.vel)
  }
  

  isDead() {
    var d = dist(this.pos.x, this.pos.y, 0, 0)
 
    if(d > this.maxR || this.life < 1) return true
    else return false
  }
}