var stopX = 250;

var startY = 30

var stopY = 250

var x = startX;

var y = startY;

var step = .05;

var pct = 0;

​

function setup() {

  createCanvas(400, 400);

}

​

function draw() {

  background(220);

  if(pct<1){

    x = startX + ((stopX-startX) * pct)

    y = startY + ((stopY-startX) * pct)

    pct +=step;

  }

  ellipse(x,y,20,20);

}