Real-Time Physics Simulation Forum

For multi-threading you need to compile using BT_ENABLE_THREADSAFE and use btCollisionDispatcherMt and btDiscreteDynamicsWorldMt. It seems quite a bit more involved than just switching out those classes. If you do only that: Assertion `gBtTaskScheduler != NULL' failed. It looks like all the task ma...

Thanks. If the C Flags need to be present in both lib and app, and need to be consistent, then a possible way to guarantee that is to have pkg-config handle it. Currently it does not: $ pkg-config --cflags bullet -I/usr/local/include/bullet -I/usr/local/include I would help you add it, but I am not ...

>It looks like you got inspired by Dennis Gustafsson What Dennis does is pretty much higher magic :-) The most impressive game tech I ever saw. My inspiration is bringing this 2D game into the third dimension: https://twitter.com/BramStolk/status/1051212736359673856 I'm beginning to think I underes...

Thank you Erwin, That's useful to know. I guess the broadphase works well enough. For this scene: https://pbs.twimg.com/media/Dr_odHZVAAAoHdv.jpg I get: numobj: 178 numpairs: 1245 maxpairs: 31684 pairs per obj: 7.0 percentage: 3.9 So every object is tested, on average against 7 others. It's hard to ...

I am trying to improve the performance of the collision testing. So a good place to start would be to see how effective the broadphase is. I tried calling: virtual void btBroadphaseInterface::printStats() But I see nothing in stdout, when I call this? I've tried it with btAxisSweep3 and btDbvtBroadp...

With Linux perf tool, I see that my sim spends roughly the same amount of time in performDiscreteCollisionDetection() and solveConstraints() function. I found SimulationIslandManagerMt which I assume will speed up the latter. But what about collision testing? Can that be done in parallel as well?

Works beautifully now: https://youtu.be/D57gCD78YpI Nice to see that the sim is deterministic too! On my machine I see a factor 15 between the performance of single-contact versus SAT. 6ms versus 90ms or so. But the non-SAT version seems quite usable. Thanks, Erwin. PS: I've send you a pull request ...

>> Any idea why the fragments dance around like that? Perhaps the vertices are not centered around the origin? The center of mass needs to be at [0,0,0]. Argh, YES, thank you. I had added the fall height to the shape verts, instead of the body world tramsform. It all makes sense now. Thanks again.

Procedural destruction of convex shapes using Voronoi, at 240Hz simulation rate.

https://youtu.be/41kVpew8iTI

I am happy with the stability of convex/convex intersections. Performance needs more work, as it goes below 30 fps.

Thanks Erwin, For proper benchmarking, I switched to Release. I also decided to add a new Benchmark demo to your Example Browser for this purpose. https://pbs.twimg.com/media/Dq8LAyVUwAATrrK.png I've added it, but the results are puzzling to me: https://youtu.be/YrcxyKLkBcE I've gone over the code m...

Thanks Erwin, not sure why I missed that. I implemented the sphere test, and it works, but there is a problem with filtering. I don't get all collision objects. Only the ones in group 0x1. I use this code: btSphereShape sph( radius ); btCollisionObject obj; obj.setCollisionShape( &sph ); obj.set...

First things first: Amazing job on Bullet! I find the convex collisions a lot more stable and accurate than what I get on OpenDE. The bad news is that the performance seems to be a lot lower, as seen in this video: https://www.youtube.com/watch?v=PiMK5A24dkE&feature=youtu.be When I use btDispatc...

I am trying to find out what collision objects are in the neighbourhood of a location in the world. Is there a way to do a quick query, or collision test of sphere versus world? I need the query only on mouse clicks, so prefer not to add an object to my world permanently to do this, as it's just a o...

Thanks Erwin,

Please note that btHinge2Constraint() deviates from this, and seems to follow OpenDE's use of global axes instead?

Erwin Coumans wrote:What is the radius of the sphere? Have you compared your setup with the Bullet/Demos/RollingFrictionDemo?
Thanks!
Erwin

My radius is 0.05 but changing it to 1.0 did not help.
I don't see any obvious differences in setup with the rolling friction demo.