var b = 10;

var g= 10;

​

function setup() {

  createCanvas(800, 400);

}

​

function draw() {

  for (var x=0; x<mouseX; x=x+50) {

    for (var y=0; y<mouseY; y=y+50) {

   r=map(mouseX, mouseY, 600, 40, 255);

    b=map(mouseX, mouseY, 600, 255, 40);

     g=map(mouseX, mouseY, 600, 112, 0);

    stroke(10);

    strokeWeight(2)

    fill(r, g, b);

    ellipse(x, y, mouseX-400, mouseY-400);

  }

  }

​

  if (mouseX >300 && mouseX < 500 && mouseY >100 && mouseY <300) { 

    fill(0);

  }

  if (mouseIsPressed) {

    background(255);

  }

  rectMode(CENTER);

  rect(width/2,height/2, 200,200);

  print(mouseX, mouseY);

}