random

let vecLocation = [];

let vecVelocity = [];

const num = 100;

function setup() {

  createCanvas(windowWidth, windowHeight);

  frameRate(60);

  a = random(10, 30);

  b = random(1, 195);

  c = random(1, 195);

  d = random(1, 195);

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

    vecLocation[i] = createVector(random(0, windowWidth), random(0, windowHeight));

    vecVelocity[i] = createVector(random(-10, 10), random(-10, 10));

  }

}

​

function draw() {

  background(0);

  noStroke();

  fill(b, c, d);

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

    ellipse(vecLocation[i].x, vecLocation[i].y, a, a);

    vecLocation[i].add(vecVelocity[i]);

    if(vecLocation[i].x > width || vecLocation[i].x < 0) {

      vecVelocity[i].x = vecVelocity[i].x * -1; 

    }

    if (vecLocation[i].y > height || vecLocation[i].y < 0) {

      vecVelocity[i].y = vecVelocity[i].y * -1;

    }

  }

}