Search found 6 matches

by ivanisavich
Sun Nov 18, 2018 10:25 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Question about PBD stabilization
Replies: 1
Views: 1019

Question about PBD stabilization

I have a question related to PBD in the context of a grain/sand simulation. I understand some solvers implement a stabilization step prior to the main constraint solver loop, where solid-surface interpenetrations are resolved, and the position deltas are added to both the current position and the pr...
by ivanisavich
Tue Jun 13, 2017 8:44 am
Forum: General Bullet Physics Support and Feedback
Topic: SoftBody collision inaccuracies
Replies: 3
Views: 1396

Re: SoftBody collision inaccuracies

I've got everything working now I think. Turns out the rest of the interpenetrations were caused by vertex bounding boxes jumping over the ground plane collision margins. I modified the bounding box generation code to expand AABBs to include the previous timestep vertex locations, as a way of faking...
by ivanisavich
Tue Jun 13, 2017 6:08 am
Forum: General Bullet Physics Support and Feedback
Topic: SoftBody collision inaccuracies
Replies: 3
Views: 1396

Re: SoftBody collision inaccuracies

So I think I've tracked down part the problem to a pretty interesting bug. This doesn't fix all ground interpenetrations...but it fixes some of them, especially when contact point locations vary greatly (which will make sense when you read what the bug is). There is some caching going on in btSoftBo...
by ivanisavich
Tue Jun 13, 2017 12:25 am
Forum: General Bullet Physics Support and Feedback
Topic: SoftBody collision inaccuracies
Replies: 3
Views: 1396

Re: SoftBody collision inaccuracies

Here are two example videos showing the issue: In this one, I spawn some single-triangle btSoftBody objects over a ground plane. You can see that some collide, some swing through partially, and one completely penetrates the plane. This is with 100 substeps per frame (3000 steps per second): http://w...
by ivanisavich
Mon Jun 12, 2017 11:36 pm
Forum: General Bullet Physics Support and Feedback
Topic: SoftBody collision inaccuracies
Replies: 3
Views: 1396

SoftBody collision inaccuracies

I'm having trouble with SoftBody collisions. I have a ground plane (btStaticPlane) and some cloths (btSoftBody, 10x10 vertex planes) that fall onto the ground plane. When my simulation steps are .0333f (30 steps per second) the falling cloth objects easily penetrate the ground and don't collide with...
by ivanisavich
Sat Jun 10, 2017 9:54 pm
Forum: General Bullet Physics Support and Feedback
Topic: Performance tips? (OpenCL/multi-threading/etc)
Replies: 3
Views: 2116

Performance tips? (OpenCL/multi-threading/etc)

I'm migrating my physics code for an application I'm working on from PhysX to Bullet, to do some performance testing. My application uses rigidbodies, constraints and cloth. Initially I was under the impression that Bullet supports OpenCL computations, which greatly improve simulation performance......