Contact Manifold Points

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jayasimha
Posts: 4
Joined: Fri Dec 30, 2016 6:18 am

Contact Manifold Points

Post by jayasimha » Tue Jan 03, 2017 12:33 pm

Hi

i am Implementing Bullet for Collision Detection in my Case there are 5 Dynamic Collision Objects and 1 Static Collision Object.
all Dynamic Objects are Touching at a time on static Object i am getting some Contact Manifold points but i am Not getting all Contact Points
for every Dynamic Object at a Time.

is it Possible to Get All Contacts points by Every Dynamic Object ?

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drleviathan
Posts: 371
Joined: Tue Sep 30, 2014 6:03 pm
Location: San Francisco

Re: Contact Manifold Points

Post by drleviathan » Tue Jan 03, 2017 3:17 pm

There are three reasons I can think of why your dynamic objects sometimes might not have contact points:

(1) When a dynamic object is being deactivated Bullet will not compute contact points for it. The contact manifolds are recomputed every substep and for optimization purposes they are not computed for objects that are at rest and not moving. Perhaps your objects slow down enough to get deactivated?

(2) Rolling and sliding dynamic objects can bounce and momentarily cease touching the floor underneath them. Since the contact manifolds are constantly recomputed there may be small but long-enough bounces where they do not touch the floor for one or more substep.s Two things are possible in this situation: (a) they have no contact manifold or...

(3) ... (b) they have a contact manifold but there are zero points inside it (I've seen this happen).

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