Real-Time Physics Simulation Forum

A good place to start would be a youtube video that shows the Bullet collision margin and how that changes the effective shape during collisions. The video points out Box-Box collisions don't use the margins, however Box-Sphere collisions do:

https://www.youtube.com/watch?v=BGAwRKPlpCw&t=2s

I see. Then I think the translation from Unity's component system to Bullet would go something like this: Object with RigidBody and Collider components --> dynamic Bullet RigidBody with Shape Object with RigidBody component --> dynamic Bullet RigidBody with Shape but set collisionless Object with Co...

I don't understand your distinctions between Unity (which is a game platform and can be configured to use Bullet for its physics engine) and Bullet (which is just a physics engine). It sounds to me like you're confusing the RigidBody (which would be your Collider) with a GameObject (which would repr...

Alternatively, you could use the CProfileManager API to get some detailed information about where the time is being spent. Look in the btQuickprof.h file for see its API. In short you can call CProfileManager::reset() before your stepSimulation(), then CProfileManager::dumpAll() after.

In my experience that "Overflow in AABB, object removed from simulation" assert happens when NaN has been injected into the system. I've seen this happen in two ways: (a) dividing by zero somewhere or (b) every frame: using a transform to compute its new value and then neglecting to renormalize it.

What are the values of BoxExtent ? If the eigenvalues of the inertia tensor have a high, mid, and low value AND you rotate the object around the axis parallel to eigenvector that corresponds to the "mid" eigenvalue then there is a natural instability where the spinning object will flip like that. Fo...

I wouldn't be surprised to learn that several btPairCachingGhostObjects each overlapping several other objects could put a heavy load on Bullet's simulation. Here is some ideas that might be helpful: (1) By default Bullet will update every Aabb of every static object every substep. Normally this def...

the body will disappear, to never come back even when the next update arrives

It sounds to me like there is an instability in your simulation. When NaN gets injected into BulletC++ it crashes but the JS implementation you are using may misbehave in other ways.

There is a phenomenon known as the "physics simulation spiral of death" where the real time to compute the world's next state is larger than the timestep itself. On each step the simulation falls further behind. This can happen when the world has too many objects or the objects are too complex. A si...

Yes, the angular velocity is capped for safety. Yes, you can change it. This thread has the info you seek.

I too would like to have a really smart convex-decomposition tool that could suggest optimized shape approximations for mesh sub parts. I'll probably eventually try to write one myself but I think it is a year or two down the road. I've got a few ideas on how one would go about it, but they are most...

Do you mean: "How to implement a planet's gravitational field in Bullet?" ? If so, here is some info: Bullet has a World gravity setting ( btDiscreteDynamicsWorld::setGravity() ) but it is uniform. You can override the World gravity on a per-object basis: btRigidBody::setGravity() . For a radial gra...

btBvhTriangleMeshShape works fine for collisions with other shapes. However, RigidBodies that use btBvhTriangleMeshShape must be static , they can't be dynamic or kinematic. The reason, I think, is that Bullet has not implemented the btBvhTriangleMeshShape vs btBvhTriangleMeshShape collision algorit...

The extra low center of mass (COM) might be contributing to its "hop" into the air on collisions. Maybe try dialing it higher to see how it affects that problem. Perhaps there is a sweet spot for how low to make the COM. Dunno if these other ideas will work but they are what I would try: (1) Increas...

I have one idea you could try: Give the vehicle a very low center of mass (COM). It is pretty easy to do this by wrapping your existing shape with a btCompoundShape. You can even put the COM outside the bounds of the body, below the wheels, which would make it automatically self-righting (unflippabl...