Search found 25 matches

by Geometrian
Fri Apr 29, 2022 7:44 am
Forum: General Bullet Physics Support and Feedback
Topic: Static `btConvexHullShape` Not Participating in Collisions
Replies: 2
Views: 3915

Re: Static `btConvexHullShape` Not Participating in Collisions

Does the object properly collide when you supply it with a different shape but leave all other code unchanged? Replacing it with a box, I saw that collisions failed there too. Comparing that with my working box code, I was able to trace it down to a problem with the transforms—specifically, the tra...
by Geometrian
Thu Apr 28, 2022 1:35 am
Forum: General Bullet Physics Support and Feedback
Topic: Static `btConvexHullShape` Not Participating in Collisions
Replies: 2
Views: 3915

Static `btConvexHullShape` Not Participating in Collisions

I'm trying to make a simple square static pyramid collision object. It seems I'm supposed to do this with `btConvexHullShape`: btConvexHullShape* shape = new btConvexHullShape; shape->addPoint(btVector3(-1,-1,0)); shape->addPoint(btVector3( 1,-1,0)); shape->addPoint(btVector3( 1, 1,0)); shape->addPo...
by Geometrian
Mon Oct 17, 2016 2:16 am
Forum: General Bullet Physics Support and Feedback
Topic: btSoftBody Internal Forces
Replies: 1
Views: 2859

btSoftBody Internal Forces

Hi, I'm trying to get some kind of measurement of internal forces from btSoftBody. (I need to measure the stress on each link for an engineering simulation. This would also be useful for computing tension in ropes, tearing cloth, etc.) I have found a few scattered posts , but no answers. I also trie...
by Geometrian
Wed Nov 19, 2014 8:37 am
Forum: General Bullet Physics Support and Feedback
Topic: Volume of btConvexHullShape
Replies: 2
Views: 4456

Volume of btConvexHullShape

I need to calculate the volume of a "btConvexHullShape" (more accurately, I need to compute a mass, but I'll do this through a density). Short of implementing my own convex hull algorithm, what should I do? I considered making a temporary "btConvexTriangleMeshShape" and then usin...
by Geometrian
Thu Mar 20, 2014 6:51 pm
Forum: General Bullet Physics Support and Feedback
Topic: Soft Body Self Collision Detection
Replies: 0
Views: 6084

Soft Body Self Collision Detection

Hi, I have found a few posts about doing various kinds of softbody collision detection with Bullet 2, but none helpful. I am specifically interested in colliding concave softbodies with themselves, with concave rigid bodies, and with other concave soft bodies. From what I've ascertained, there is so...
by Geometrian
Tue Nov 26, 2013 9:32 pm
Forum: General Bullet Physics Support and Feedback
Topic: Memory Leak from Linking
Replies: 10
Views: 11172

Re: Memory Leak from Linking

This still occurs in 2.82.

I'm fairly sure at least part of the problem is that the "static btClock gProfileClock;" declared at btQuickprof.cpp:21 allocates memory that is never freed.
by Geometrian
Thu Nov 21, 2013 11:52 pm
Forum: General Bullet Physics Support and Feedback
Topic: getPersistentManifold() Returns NULL
Replies: 1
Views: 2564

getPersistentManifold() Returns NULL

Hi, I have a compound object and I'm trying to collide it against various things. I can't seem to figure out why, but in certain situations, my code crashes since getPersistentManifold() is returning NULL. My near callback is below: void _fz_near_callback(btBroadphasePair& collisionPair, btColli...
by Geometrian
Tue Jun 25, 2013 7:26 am
Forum: General Bullet Physics Support and Feedback
Topic: Near Callback Discard
Replies: 1
Views: 2963

Near Callback Discard

Hi, I need to be able to test whether to let two objects collide after detecting whether they would. For example, if there are two separate cubes, the instant they actually start to intersect is when I decide whether to let Bullet continue processing the collision. To this end, I have implemented a ...
by Geometrian
Sun Jun 02, 2013 9:00 pm
Forum: General Bullet Physics Support and Feedback
Topic: Box-Sphere Inaccurate Collision
Replies: 2
Views: 4205

Re: Box-Sphere Inaccurate Collision

The collision margin was exactly the problem--I had no idea it even existed!

The scene I discovered it in was a sphere of radius 10cm rolling over boxes of size 1m on a side.

Thanks!
by Geometrian
Wed May 29, 2013 4:12 am
Forum: General Bullet Physics Support and Feedback
Topic: Box-Sphere Inaccurate Collision
Replies: 2
Views: 4205

Box-Sphere Inaccurate Collision

Hi, When a box (btBoxShape) and a sphere (btSphereShape) collide, the collision is very good on faces, but inaccurate at edges/corners. My tests show that on edges, the amount of penetration relative to the size of the box can range from 0.5% to 2.0%. It seems to be independent of the time step--I t...
by Geometrian
Wed May 15, 2013 10:35 pm
Forum: General Bullet Physics Support and Feedback
Topic: Guaranteed Collision Callback
Replies: 3
Views: 5288

Guaranteed Collision Callback

Hi, I am attempting to figure out when two objects collide. What I want: Ideally, whenever a collision actually occurs , Bullet would call a callback, giving me the option to ignore the collision or allow Bullet to continue with collision response (restitution, reaction, etc.). Some things close and...
by Geometrian
Thu Apr 18, 2013 10:31 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Facilities for Physics-Based Animation
Replies: 0
Views: 5052

Facilities for Physics-Based Animation

I'm looking for a way to animate humanoid characters in a physically-based manner. I looked around a bit, but wasn't able to find anything useful in the way of a toolkit--mostly it's just technical papers on the topic. I figured I would ask the people who follow such things more closely. My requirem...
by Geometrian
Sun Apr 14, 2013 1:50 am
Forum: General Bullet Physics Support and Feedback
Topic: BT_DECLARE_ALIGNED_ALLOCATOR new Operator Overload
Replies: 4
Views: 6767

Re: BT_DECLARE_ALIGNED_ALLOCATOR new Operator Overload

Figured it out. The library indeed didn't overload "new", but it did #define it to something else, for purposes of catching memory leaks: #define DEBUG_NEW new( _NORMAL_BLOCK, __FILE__, __LINE__ ) #define new DEBUG_NEW Is it possible to keep this definition, or something similar, but still...
by Geometrian
Sun Apr 14, 2013 12:13 am
Forum: General Bullet Physics Support and Feedback
Topic: BT_DECLARE_ALIGNED_ALLOCATOR new Operator Overload
Replies: 4
Views: 6767

Re: BT_DECLARE_ALIGNED_ALLOCATOR new Operator Overload

*Bump* I don't know why this could be happening. The other library doesn't overload new as far as I know (although it certainly uses it). The problem doesn't seem to occur if the library's header files are included after Bullet's and if no "new" allocations happen for Bullet objects in tha...
by Geometrian
Sun Apr 07, 2013 7:09 pm
Forum: General Bullet Physics Support and Feedback
Topic: Memory Leak from Linking
Replies: 10
Views: 11172

Re: Memory Leak from Linking

So memory leak appears after you add functionality, which is never executed? In that case, are you sure you destroy all objects you created? physics->removeRigidBody(...); delete RigidBody; delete CollisionShape; Are you sure it's not your code causing leak at all? Exactly. The code that's causing ...