for example, there are 2 boxes in a room,
i only want to the box can collision with the room's wall,
i do not want to the collision between the boxes,
how can i do it ?
thanks!
There are a few ways. The easiest is to assign different collision groups, and collision filter flags to the boxes.
By default, once you add a rigidbody to the dynamics world, it gets automatically assigned collision filter flags: this prevents collision between static versus static objects. In code this is:Code:
short collisionFilterGroup = isDynamic? btBroadphaseProxy::DefaultFilter : btBroadphaseProxy::StaticFilter; short collisionFilterMask = isDynamic? btBroadphaseProxy::AllFilter : btBroadphaseProxy::AllFilter ^ btBroadphaseProxy::StaticFilter;rigidbody->getBroadphaseProxy()->m_collisionFilterGroup = collisionFilterGroup;rigidbody->getBroadphaseProxy()->m_collisionFilterMask = collisionFilterMask;
The collisionFilterMask determines (filters) the collision objects belonging to certain collisionFilterGroups to collision with. The group/mask is stored as short integer,so this gives 16 different groups of objects. Some default groups are defined:Code:
///optional filtering to cull potential collisions enum CollisionFilterGroups { DefaultFilter = 1, StaticFilter = 2, KinematicFilter = 4, DebrisFilter = 8, AllFilter = DefaultFilter | StaticFilter | KinematicFilter | DebrisFilter,};
Thanks,
Erwin
PS: If you need more fine grain control, you can override the 'needsCollision' by deriving your own version of the btCollisionDispatcher. This is tricky, so I might just add some callback that you can register for to prevent collisions between certain objects.Statistics: Posted by Erwin Coumans — Fri Nov 24, 2006 1:00 pm
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