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I've done my first BreakOut Game while completing an assignment for Stanford University CS Online Course for java.

However I noticed during play testing that when the ball sometimes hits a brick while travelling diagonally it ends up hitting several bricks in a row in a unnatural way.

I'm guessing I have to improve a bit my collision detection code and I tried several things already to no avail.

I'm using the ACM library for this program. An imaginary Rectangle surrounds my ball and I use the 4 corners of that rectangle to detect collision.

During the game, since I added several addons (items that drop and give you bonus) there are lot of velocity changes in the game - the vx variable change a lot.

I think this is related to my problem, because I noticed that it's when the ball travels at more speed than more of this several bricks destroyed in a row problem.

I´ll add the relevant code here. You can however check out all of the code here: https://gist.github.com/frodosda/5604272

// Defines the initial Direction of the Ball - inside the "MoveBall" Method
    vx = rGen.nextDouble(1.0, 3.0); // Random Horizontal Direction
    if (rGen.nextBoolean(0.5)) vx = -vx;
    vy = 2.0; // Vertical Direction

/** Checks if the ball collided or not with an object */

private void verificarColisaoBola () {

    GObject objColisao = getObjColisao(); // The object with wich the ball colided

    if (objColisao == raquete) { // If colidded with paddle
        vy = -vy; // Change vertical tranjectory of ball
        // prevents that the ball get "glued" to the paddle
        bola.setLocation(bola.getX(),bola.getY() - PADDLE_HEIGHT / 2);

        // Changes the direction of the ball when it hits the borders of the paddle - provides the player more control
        if ((bola.getX() < raquete.getX() + 0.20 * raquete.getWidth() && vx > 0)
            || (bola.getX() > raquete.getX() + 0.80 * raquete.getWidth() && vx < 0)) {
            vx = -vx;
        }

    } else if (objColisao != null) { // Colision with a brick
        remove (objColisao); // remove the brick
        nTijolos--; // counts one less brick
        vy = -vy; // Changes vertical direction
}

/** Finds if the limits of the ball - 4 corners - hits an object  
 * @return The object that collided with the ball - or null */

private GObject getObjColisao () {
    if (getElementAt (bola.getX(), bola.getY()) != null) { // Top left corner
        return getElementAt (bola.getX(), bola.getY());
    } else if (getElementAt (bola.getX() + bola.getWidth(), bola.getY()) != null) { // Top Right corner
        return getElementAt (bola.getX() + bola.getWidth(), bola.getY());
    } else if (getElementAt (bola.getX(), bola.getY() + bola.getWidth()) != null) { // Bottom Left corner
        return getElementAt (bola.getX(), bola.getY() + bola.getWidth());
    } else if (getElementAt (bola.getX() + bola.getWidth(), bola.getY() + bola.getWidth()) != null) { // Bottom Right corner
        return getElementAt (bola.getX() + bola.getWidth(), bola.getY() + bola.getWidth());
    } else {
        return null;
    }
}

Thanks in advance for your help!

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1 回答 1

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您需要检查您的时间步长。具有大时间步长的速度通常会导致对象在下一个时间步长中撞击多个项目。所以让你的时间步长更小，以使碰撞检测更频繁地发生。

您还应该进行一些更智能的分析并检查您会碰到的第一块砖（具有最大/最小 x 或 y 值的砖），然后停在那里。然后你需要计算碰撞后球的最终位置，这样即使时间步长很大，球也能正常运行。

于 2013-05-18T13:23:16.980 回答