Real-Time Physics Simulation Forum

Wow, a lot has changed in Bullet since I was last using it. I ended up ditching Bullet in 2012 because of performance reasons (no offense, Erwin). When I dropped 2000 balls on a terrain heightfield, no matter what I did to tell the collision detection code "these objects cannot collide with one...

I realize I relied too heavily on the links to do the summarizing for me. I have updated the OP to include a "Problem Overview" section (and also section names). When I said "motors" I meant it figuratively; I don't actually use volts/watts/amps. I control the torques directly fo...

Inverse kinematics (or any sort of motion planning) will give me per-bone x , v , a , θ , ω , and α , but a simulated character cannot manipulate any of these quantities directly. What I have control over is the per-joint applied torques τ . Consider the seemingly mundane task of maintaining the ini...

This question is a bit different from the usual "How do I simulate X?" that gets asked on here... I have the simulation aspect working, and am trying to figure out how to control it, i.e. "what values do I need to send to the motors to produce Y behavior?" If there's another foru...

When the current orientation matches the target orientation, trDeltaAB is the identity transform, qDeltaAB is the identity quaternion, and m_swingAxis is a zero vector. Normalizing it causes my game universe to be devoured by a black hole of NaN . This code snippet is lines 630-649 of btConeTwistCon...

Oh wow, I didn't notice this got another reply. Ah yes, the needsBroadphaseCollision function is the O(n²) function I was referring to in my original post. Is needsBroadphaseCollision called once every step of the simulation, or only once per pair? I had figured it was a once-every-tick thing, but i...

Hm... I'm going to feel silly if it's as simple as this, but... would it work to have the bones of the ragdoll as parts of a btCompoundShape?

Hm... getOverlappingPairArray ... could be useful, if I decide to go that route. I had read about the collision groups/masks, but I couldn't see any way to use that for my particular situation. That seems to be aimed at specifying categories of objects that can interact. In my case, however, there a...

Maybe if I do something about other people's unanswered questions someone will answer mine...

I believe the angles are supposed to be in radians, not degrees.

Alternatively, is there some "correct" way to have multiple active ragdolls at once, without a huge performance hit? The ragdoll I am using has 21 bones; I get the same performance hit when I create the rigid bodies without adding any constraints between them. Thus I have concluded that it...

On closer examination, I notice that in struct btDbvtBroadphase there is a member btOverlappingPairCache* m_paircache , and that there is a method btBroadphasePair* btOverlappingPairCache::addOverlappingPair(btBroadphaseProxy* proxy0, btBroadphaseProxy* proxy1) , which is called in the function void...

From what I can tell Bullet allows you to specify, for some pair of collision objects, whether to do a collision check / collision response... is it possible to do this on an opt-in basis instead? What I'd like to be able to do is something like the broad phase, but instead of calling some function ...

In my project I am reading/writing bullet collision shapes... it seemed to be working properly, but I noticed that btMultiSphereShapes were not loading properly. After a great deal of hair-pulling, I found out what was causing the problem. Shapes of type btMultiSphereShape, and a few other types, ar...