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Bullet Physics Tutorial: Getting Started

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1

Learn how to make a simple OpenGL ES Arkanoid game have 3D physics and collision detection in this Bullet Physics tutorial!

This is a companion discussion topic for the original entry at https://www.raywenderlich.com/2606-bullet-physics-tutorial-getting-started
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You have several issues in your code:
-One is the way you normalize your speed of the breakout ball.
-The other is related to your border vertex definition. I get AABB issues, like described here:
http://www.bulletphysics.org/Bullet/phpBB3/viewtopic.php?f=9&t=2818

The first one can be fixed by using the the following way to normalize your speed:

btVector3 newVelocity(0,0,0);
btVector3 normalizedCurrentBallDirection(0,0,0);
if(!m_ball->m_body->getLinearVelocity().isZero()){
	normalizedCurrentBallDirection = m_ball->m_body->getLinearVelocity().normalized();
}
else if(!m_last_ball_direction.isZero()){
	normalizedCurrentBallDirection = -m_last_ball_direction.normalized();
}

newVelocity = normalizedCurrentBallDirection* m_desiredVelocity;
m_last_ball_direction = m_ball->m_body->getLinearVelocity();
m_ball->m_body->setLinearVelocity(newVelocity);

You need to keep the m_last_ball_direction because it might happen that your ball completely stops when hitting a brick. In this case, your way of normalization causes a division by zero error (and mine as well, that is why I check isZero). If the ball stops, we recover its speed by inverting the last known direction and multiplying it by the desired speed.

The other issue I can explain as soon as I have a fix.

Edit: The AABB issue seems to have disappeared, not sure tough if for the better or worse.

3

This tutorial is more than six months old so questions are no longer supported at the moment for it. We will update it as soon as possible. Thank you! :]