let x2, y2, x2speed, y2speed;

​

function setup() {

    createCanvas(400, 400);

    x1 = width / 2;

    y1 = height / 2;

    x1speed = 1;

    y1speed = 3;

    x2 = width / 2;

    y2 = height / 2;

    x2speed = 2;

    y2speed = -3;

}

​

function draw() {

    background(220);

​

    move(x1, y1, x1speed, y1speed);

    x1speed = bounce(x1, 0, width, x1speed);

    y1speed = bounce(y1, 0, height, y1speed);

​

    drawball(x1, y1);

​

    move(x2, y2, x2speed, y2speed);

    x2speed = bounce(x2, 0, width, x2speed);

    y2speed = bounce(y2, 0, height, y2speed);

    drawball(x2, y2);

}

​

function move(x, y, xspeed, yspeed) {

    x += xspeed;

    y += yspeed;

    return 

}

​

function drawball(x, y) {

    ellipse(x, y, 50, 50);

}

​

function bounce(x, low, high, speed) {

    if (x < low || x > high) {

        speed *= -1;

    }

    return speed;

}