Getting list of triangles involved in collision.

Rademanc · **Joined:** Mon Nov 02, 2009 11:55 am **Posts:** 11

Hi there.
I have a thorny problem.
I have a wall(triangle mesh) and I need to figure out which parts of the wall have been colliding with a cone. Is there a way to retrieve a list of the triangles that are colliding with the Cone?
Is there another way to do this?

smallping · **Joined:** Fri Oct 19, 2012 3:37 am **Posts:** 2

Hi, I have the same problem. Does Bullet support this or not?
I found in the manual, a callback function

virtual btScalar btCollisionWorld::ContactResultCallback::addSingleResult ( btManifoldPoint & cp,
const btCollisionObject * colObj0,
int partId0,
int index0,
const btCollisionObject * colObj1,
int partId1,
int index1
)

In this function, the index0 and index1 is the index of colliding triangles, or not?

Erwin Coumans · **Posted:** Sun Oct 21, 2012 7:03 pm

Yes you can use a callback to find the actual triangle (and part) index.

The index and partId points to the triangle index and (optional) part of a triangle mesh, in case you are using btBvhTriangleMeshShape.

Note that it is best to use Bullet-2.81, the interface changed slightly:

Code:

static bool ContactAddedCallback(btManifoldPoint& cp,   const btCollisionObjectWrapper* colObj0Wrap,int partId0,int index0,const btCollisionObjectWrapper* colObj1Wrap,int partId1,int index1);

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Getting list of triangles involved in collision.

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