var player,

    computer,

    ball;

var paddles;

var computerPos;

var scoreText;

​

const canvasDimensions = [600, 400];

const RAD2DEG = 180 / Math.PI;

const DEG2RAD = Math.PI / 180;

​

function rand(a, b) {

    return (a + Math.random() * (b - a));

}

​

function setup() {

    createCanvas(canvasDimensions[0], canvasDimensions[1]);

    background(20);

​

    fill(255);

    textAlign(CENTER);

​

    paddles = new Group();

​

    player = createSprite(20, height / 2, 5, 50);

    player.shapeColor = 'white';

    paddles.add(player);

​

    computer = createSprite(width - 20, height / 2, 5, 50);

    computer.shapeColor = 'white';

    paddles.add(computer);

​

    ball = createSprite(width / 2, height / 2, 8, 8);

    ball.shapeColor = '#c6ed2c';

​

    computerPos = Array.apply(null, Array(10)).map(Number.prototype.valueOf, height / 2);

    score = [0,0];

​

    ball.setSpeed(2, rand(-10, 10));

}

​

function draw() {

    background(20);

    drawSprites();

​

    // set play paddle position to mouse position, within bounds

    player.position.y = Math.max(0, Math.min(height, mouseY));

​

    // perfect computer player

    // computer.position.y = ball.position.y;

​

    // delayed computer player

    computerPos.push(ball.position.y);

    computer.position.y = computerPos.shift();

​

    // wall collisions

    if (ball.position.y < 4 || ball.position.y > height - 4) {

        ball.velocity.y *= -1;

    }

​

    // goal collisions

    if (ball.position.x < 4) {

        score[1]++;

        ball.position.x = width/2;

        ball.position.y = height/2;

        ball.setSpeed(2, rand(170,190));

    }

    else if (ball.position.x > width - 4) {

        score[0]++;

        ball.position.x = width/2;

        ball.position.y = height/2;

        ball.setSpeed(2, rand(-10,10));

    }

​

    // ball/paddle collisions

    ball.overlap(paddles, function(ball, paddle) {

        ball.velocity.x *= -1.01;

        ball.velocity.y += (ball.position.y - paddle.position.y) / 20;

    });

​

    scoreText = score[0] + " – " + score[1];

    text(scoreText, width/2, 20);

}

​