Removing a rigid body, but still getting collisions for it

Question

What is the correct way to remove a rigid body, I am doing just this to remove it:

void removeRigidBody(btDynamicsWorld* pDynamicsWorld, btRigidBody* rb)
{
   pDynamicsWorld->removeRigidBody(rb);
   delete rb->getMotionState();
   delete rb;
}

However, the object still appears in pDynamicsWorld->getCollisionObjectArray() after I do a pDynamicsWorld->stepSimulation

Strangely enough this does not happen on ARM, just x86.

@zeller I have not, so this is correct method as far as you know? — weston, May 27 '13 at 13:36
@zeller I've asked now: http://bulletphysics.org/Bullet/phpBB3/viewtopic.php?f=9&t=9129 Thanks — weston, May 27 '13 at 13:43
Ok. See my answer. Maybe it helps. LMK if not and I'll delete it. — zeller, May 27 '13 at 13:46
Can't delete question, don't think it's that useful to anyone else. So feel free to vote to close it. — weston, May 27 '13 at 23:06

zeller · Answer 1 · 2013-05-27T13:53:59.057

1

Actually, this is what I've found. Posting code in the comments would look awful, that's why the answer instead.

     //remove the rigidbodies from the dynamics world and delete them
    int i;
    for (i=m_dynamicsWorld->getNumCollisionObjects()-1; i>=0 ;i--)
    {
            btCollisionObject* obj = m_dynamicsWorld->getCollisionObjectArray()[i];
            m_dynamicsWorld->removeCollisionObject( obj );
            delete obj;
    }

So you remove the body from the collision objects.

edited May 27 '13 at 13:53

answered May 27 '13 at 13:46

zeller

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Thanks, I gave it a shot, but the `removeRigidBody` calls `removeCollisionObject` anyway (in `btDiscreteDynamicsWorld`), so it didn't make any difference. – weston May 27 '13 at 14:02
I've asked someone at our local gamedev forum who uses bullet v281 and he said it's clearly not normal behavior. Though that's as far as I can help, I hope you'll get your answer at the bullet forums. – zeller May 27 '13 at 16:43
thanks for your effort, it was a stupid bug, please see my answer for details. – weston May 27 '13 at 17:01

weston · Accepted Answer · 2013-05-27T17:14:00.110

0

This was, like most bugs just a stupid mistake. Sorry to those who took time to read it.

The error was actually in some java that called the removeRigidBody by jni.

if (body.id > 0) {

The id is actually an int cast of the btRigidBody address, so of course any != 0 integer could be a valid address. On the x86, the addresses happened to be < 0 which on the other device happened to be > 0.

edited May 27 '13 at 17:14

answered May 27 '13 at 17:01

weston

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So it really was a bug. Just not in bullet but in your code :) – zeller May 28 '13 at 07:12

Removing a rigid body, but still getting collisions for it

2 Answers2