​

function setup() {

  createCanvas(500, 500);

  background(255);

  noStroke();

  r = random(50, 200); // r is a random number between 0 - 255

  g = random(0,50); // g is a random number betwen 100 - 200

  b = random(50, 220) // b is a random number between 0 - 100

  a = random(150,255); // a is a random number between 200 - 255

  fill(r, g, b, a);

}

​

function draw() {

  background(255, 255, 255, 125) 

  circle(mouseX, mouseY, 100);

  if(mouseIsPressed){

    r = random(50, 200); // r is a random number between 0 - 255

    g = random(0,50); // g is a random number betwen 100 - 200

    b = random(50, 220) // b is a random number between 0 - 100

    a = random(150,255); // a is a random number between 200 - 255

    fill(r, g, b, a); 

  }

}

​