createCanvas(400, 400);

}

​

function draw() {

  background(0);

  stroke(255);

  line(200,200,mouseX,mouseY);

  var x = ave(200,mouseX);

  var y = ave(200,mouseY);

  fill(255,0,0);

  ellipse(x,y,30,30);

  var x2 = ave(x,200);

  var y2 = ave(y,200);

  fill(0,255,0);

  ellipse(x2,y2,30,30);

}

function ave(num1, num2){

  return (num1 + num2)/2;

}

​