Problem with concave/concave collision detection

Thomas · Post by **Thomas** » Fri Aug 17, 2007 3:01 pm

Hello

I am using Bullet/GImpact for polygon soup/polygon soup detection collision.
I create a btCollisionWorld, add 2 btCollisionObject with btGImpactMeshShape shapes.
However when the 2 meshes have different number of triangles it crashes in btCollisionWorld::performDiscreteCollisionDetection.
I tried to look at the code and in gim_box_set.h, line 606, I replaced
m_collision_pairs->push_pair(m_boxset1->getNodeData(node0),m_boxset1->getNodeData(node1));
by
m_collision_pairs->push_pair(m_boxset0->getNodeData(node0),m_boxset1->getNodeData(node1));

It doesn't crash anymore and seems to work but I don't know if it is the right way to do this.

Regards,

Thomas

DevO · Post by **DevO** » Fri Aug 17, 2007 7:23 pm

Are you using GIMPACT 0.2 ?
May be this is source of my problme with it...

http://continuousphysics.com/Bullet/php ... php?t=1224

Thomas · Post by **Thomas** » Sat Aug 18, 2007 5:55 am

I am using Bullet 2.55 and the GImpact shipped in the Extras directory.

Erwin Coumans · Post by **Erwin Coumans** » Sat Aug 18, 2007 4:16 pm

It looks like a bug in the optional Extras/GIMPACT library, so I fixed it.

Please test with upcoming Bullet 2.56 release if this improved GIMPACT.
Thanks,
Erwin

Thomas · Post by **Thomas** » Mon Aug 20, 2007 8:38 am

I tested with bullet 2.56. (btw great software!).
It doesn't crash.

But it seems collision is detected whereas objects are not colliding (they are quite close).

Regards,

Thomas

Thomas · Post by **Thomas** » Mon Aug 20, 2007 9:07 am

Maybe I have the problem mentioned in http://continuousphysics.com/Bullet/php ... php?t=1224

projectileman · Post by **projectileman** » Mon Aug 20, 2007 9:25 pm

Hi Thomas,

Thanks for your feedback.

You've already solve that problem with this bug fix:

Code: Select all

m_collision_pairs->push_pair(m_boxset0->getNodeData(node0),m_boxset1->getNodeData(node1));

Thanks for your contribution. I didn't make enough testing with GIMPACT meshes: the MovingConvaveDemo uses the same Bunny mesh for all objects so I didn't notice that it had problems with different meshes.

Thanks.