createCanvas(400, 400);

}

​

var c;

​

function draw() {

​

  c = map (mouseX,0,400,0,200);

  // map (input variable ,Current range min,current range max, new range min, new range max);

  var s = map (mouseX,0,400,0,255);

  background(s,0,255-s);

  rect (0,100,mouseX,20);

​

  rect (0,300,c,20);

​

   a();

}

​

​

function a (){

   ellipse(300,200,c,c); 

}