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Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

            
              <canvas id="stage" width="480" height="320"></canvas>
            
          
!
            
              #stage {
    background: salmon;
}

html,
body {
    height: 100%;
}

body {
    display: flex;
    align-items: center;
    justify-content: center;
}

            
          
!
            
              /* Graphics */

const canvas = document.getElementById('stage');
const context = canvas.getContext('2d');
context.fillStyle = 'pink';

const PADDLE_WIDTH = 100;
const PADDLE_HEIGHT = 20;

const BALL_RADIUS = 10;

const BRICK_ROWS = 5;
const BRICK_COLUMNS = 7;
const BRICK_HEIGHT = 20;
const BRICK_GAP = 3;

function drawTitle() {
    context.textAlign = 'center';
    context.font = '24px Courier New';
    context.fillText('rxjs breakout', canvas.width / 2, canvas.height / 2 - 24);
}

function drawControls() {
    context.textAlign = 'center';
    context.font = '16px Courier New';
    context.fillText('press [<] and [>] to play', canvas.width / 2, canvas.height / 2);
}

function drawGameOver(text) {
    context.clearRect(canvas.width / 4, canvas.height / 3, canvas.width / 2, canvas.height / 3);
    context.textAlign = 'center';
    context.font = '24px Courier New';
    context.fillText(text, canvas.width / 2, canvas.height / 2);
}

function drawAuthor() {
    context.textAlign = 'center';
    context.font = '16px Courier New';
    context.fillText('by Manuel Wieser', canvas.width / 2, canvas.height / 2 + 24);
}

function drawScore(score) {
    context.textAlign = 'left';
    context.font = '16px Courier New';
    context.fillText(score, BRICK_GAP, 16);
}

function drawPaddle(position) {
    context.beginPath();
    context.rect(
        position - PADDLE_WIDTH / 2,
        context.canvas.height - PADDLE_HEIGHT,
        PADDLE_WIDTH,
        PADDLE_HEIGHT
    );
    context.fill();
    context.closePath();
}

function drawBall(ball) {
    context.beginPath();
    context.arc(ball.position.x, ball.position.y, BALL_RADIUS, 0, Math.PI * 2);
    context.fill();
    context.closePath();
}

function drawBrick(brick) {
    context.beginPath();
    context.rect(
        brick.x - brick.width / 2,
        brick.y - brick.height / 2,
        brick.width,
        brick.height
    );
    context.fill();
    context.closePath();
}

function drawBricks(bricks) {
    bricks.forEach((brick) => drawBrick(brick));
}


/* Sounds */

const audio = new (window.AudioContext || window.webkitAudioContext)();
const beeper = new Rx.Subject();
beeper.sample(100).subscribe((key) => {

    let oscillator = audio.createOscillator();
    oscillator.connect(audio.destination);
    oscillator.type = 'square';

    // https://en.wikipedia.org/wiki/Piano_key_frequencies
    oscillator.frequency.value = Math.pow(2, (key - 49) / 12) * 440;

    oscillator.start();
    oscillator.stop(audio.currentTime + 0.100);

});


/* Ticker */

const TICKER_INTERVAL = 17;

const ticker$ = Rx.Observable
    .interval(TICKER_INTERVAL, Rx.Scheduler.requestAnimationFrame)
    .map(() => ({
        time: Date.now(),
        deltaTime: null
    }))
    .scan(
        (previous, current) => ({
            time: current.time,
            deltaTime: (current.time - previous.time) / 1000
        })
    );


/* Paddle */

const PADDLE_SPEED = 240;
const PADDLE_KEYS = {
    left: 37,
    right: 39
};

const input$ = Rx.Observable
    .merge(
        Rx.Observable.fromEvent(document, 'keydown', event => {
            switch (event.keyCode) {
                case PADDLE_KEYS.left:
                    return -1;
                case PADDLE_KEYS.right:
                    return 1;
                default:
                    return 0;
            }
        }),
        Rx.Observable.fromEvent(document, 'keyup', event => 0)
    )
    .distinctUntilChanged();

const paddle$ = ticker$
    .withLatestFrom(input$)
    .scan((position, [ticker, direction]) => {

        let next = position + direction * ticker.deltaTime * PADDLE_SPEED;
        return Math.max(Math.min(next, canvas.width - PADDLE_WIDTH / 2), PADDLE_WIDTH / 2);

    }, canvas.width / 2)
    .distinctUntilChanged();


/* Ball */

const BALL_SPEED = 60;
const INITIAL_OBJECTS = {
    ball: {
        position: {
            x: canvas.width / 2,
            y: canvas.height / 2
        },
        direction: {
            x: 2,
            y: 2
        }
    },
    bricks: factory(),
    score: 0
};

function hit(paddle, ball) {
    return ball.position.x > paddle - PADDLE_WIDTH / 2
        && ball.position.x < paddle + PADDLE_WIDTH / 2
        && ball.position.y > canvas.height - PADDLE_HEIGHT - BALL_RADIUS / 2;
}

const objects$ = ticker$
    .withLatestFrom(paddle$)
    .scan(({ball, bricks, collisions, score}, [ticker, paddle]) => {

        let survivors = [];
        collisions = {
            paddle: false,
            floor: false,
            wall: false,
            ceiling: false,
            brick: false
        };

        ball.position.x = ball.position.x + ball.direction.x * ticker.deltaTime * BALL_SPEED;
        ball.position.y = ball.position.y + ball.direction.y * ticker.deltaTime * BALL_SPEED;

        bricks.forEach((brick) => {
            if (!collision(brick, ball)) {
                survivors.push(brick);
            } else {
                collisions.brick = true;
                score = score + 10;
            }
        });

        collisions.paddle = hit(paddle, ball);

        if (ball.position.x < BALL_RADIUS || ball.position.x > canvas.width - BALL_RADIUS) {
            ball.direction.x = -ball.direction.x;
            collisions.wall = true;
        }

        collisions.ceiling = ball.position.y < BALL_RADIUS;

        if (collisions.brick || collisions.paddle || collisions.ceiling ) {
            ball.direction.y = -ball.direction.y;
        }

        return {
            ball: ball,
            bricks: survivors,
            collisions: collisions,
            score: score
        };

    }, INITIAL_OBJECTS);


/* Bricks */

function factory() {
    let width = (canvas.width - BRICK_GAP - BRICK_GAP * BRICK_COLUMNS) / BRICK_COLUMNS;
    let bricks = [];

    for (let i = 0; i < BRICK_ROWS; i++) {
        for (let j = 0; j < BRICK_COLUMNS; j++) {
            bricks.push({
                x: j * (width + BRICK_GAP) + width / 2 + BRICK_GAP,
                y: i * (BRICK_HEIGHT + BRICK_GAP) + BRICK_HEIGHT / 2 + BRICK_GAP + 20,
                width: width,
                height: BRICK_HEIGHT
            });
        }
    }

    return bricks;
}

function collision(brick, ball) {
    return ball.position.x + ball.direction.x > brick.x - brick.width / 2
        && ball.position.x + ball.direction.x < brick.x + brick.width / 2
        && ball.position.y + ball.direction.y > brick.y - brick.height / 2
        && ball.position.y + ball.direction.y < brick.y + brick.height / 2;
}


/* Game */

drawTitle();
drawControls();
drawAuthor();

function update([ticker, paddle, objects]) {

    context.clearRect(0, 0, canvas.width, canvas.height);

    drawPaddle(paddle);
    drawBall(objects.ball);
    drawBricks(objects.bricks);
    drawScore(objects.score);

    if (objects.ball.position.y > canvas.height - BALL_RADIUS) {
        beeper.onNext(28);
        drawGameOver('GAME OVER');
        game.dispose();
    }

    if (!objects.bricks.length) {
        beeper.onNext(52);
        drawGameOver('CONGRATULATIONS');
        game.dispose();
    }

    if (objects.collisions.paddle) beeper.onNext(40);
    if (objects.collisions.wall || objects.collisions.ceiling) beeper.onNext(45);
    if (objects.collisions.brick) beeper.onNext(47 + Math.floor(objects.ball.position.y % 12));

}

const game = Rx.Observable
    .combineLatest(ticker$, paddle$, objects$)
    .sample(TICKER_INTERVAL)
    .subscribe(update);

            
          
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