RGB

let arr = [];

let b = 700;

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  background(100);

  y = sqrt(sq(b)-sq(b/2));

  ellipse(0, 0, 20, 20);

  ellipse(b, 0, 20, 20);

  ellipse(b/2, y, 20, 20);

  for(i = b; i >= 0; i --){

    let x = i;

    arr.push(x);

  }

}

​

function draw() {

  r = arr[floor(dist(mouseX,mouseY, 0, 0))];

  be = arr[floor(dist(mouseX, mouseY, b, 0))];

  g = arr[floor(dist(mouseX,mouseY, b/2, y))];

  fill(r,g,be,100);

  noStroke()

  ellipse(mouseX, mouseY, 40);

}