Search found 99 matches

by lunkhound
Sat Nov 15, 2014 6:18 pm
Forum: General Bullet Physics Support and Feedback
Topic: CPU multithreading is working!
Replies: 145
Views: 85539

CPU multithreading is working!

https://github.com/bulletphysics/bullet3/issues/126 I'd like to get Bullet 2 running with CPU multithreading but it has been removed from recent versions of the repository. I looked up the commit that removed it (f06312c632492200ba1478ddc84c5ee474f74e54, comment is "remove most clutter (todo)"), bu...
by lunkhound
Sat Nov 15, 2014 2:21 am
Forum: General Bullet Physics Support and Feedback
Topic: Problem with vibrating bodies (alt. Character riding a bike)
Replies: 4
Views: 4249

Re: Problem with vibrating bodies (alt. Character riding a b

I've run into the same sort of problem. I managed to tame the shakes somewhat by switching to the btGeneric6DofSpringConstraint for most things and btConeTwistConstraint for shoulders. I had to tune the spring strength and spring damping parameters.
by lunkhound
Sat Nov 15, 2014 1:58 am
Forum: General Bullet Physics Support and Feedback
Topic: btHeightfieldTerrainShape : item collides but falls through
Replies: 11
Views: 11291

Re: btHeightfieldTerrainShape : item collides but falls thro

Glad to hear it worked! Yes the default behavior -- colliding with the back faces of triangles -- doesn't seem very useful. It caused me lots of problems. It is really bad when you have a jointed object like a ragdoll and one of its collision objects manages to penetrate the ground or a wall deep en...
by lunkhound
Fri Nov 14, 2014 8:08 pm
Forum: General Bullet Physics Support and Feedback
Topic: btHeightfieldTerrainShape : item collides but falls through
Replies: 11
Views: 11291

Re: btHeightfieldTerrainShape : item collides but falls thro

The heightfield collision shape is treated as just a thin polygonal surface. The terrain has no thickness to it. This can cause 2 issues: 1. fast moving small objects (without CCD enabled) can fall right through and never even detect a collision (just turn on CCD for such objects) 2. if an object en...
by lunkhound
Wed Nov 12, 2014 6:24 pm
Forum: General Bullet Physics Support and Feedback
Topic: My custom patch for collision callback events
Replies: 23
Views: 19988

Re: My custom patch for collision callback events

It is already possible to easily determine which collisions are new by inspecting the list of persistent manifolds. For each manifold there are a number of btManifoldPoints, and the manifold point has a "lifetime" value. If the lifetime is 1, then it is new. So, no need to add a flag for that. One k...
by lunkhound
Wed Aug 20, 2014 2:08 am
Forum: General Bullet Physics Support and Feedback
Topic: Question about the Code in btRaycastVehicle
Replies: 3
Views: 3022

Re: Question about the Code in btRaycastVehicle

The "force" variable could be renamed "accel" or something like that and it would make more sense. If the mass wasn't multiplied in there, then it would effectively need to be folded into the spring and damping constants. That's inconvenient because it would mean that if you changed the vehicle's ma...
by lunkhound
Wed Jul 30, 2014 8:43 pm
Forum: General Bullet Physics Support and Feedback
Topic: Question about the Code in btRaycastVehicle
Replies: 3
Views: 3022

Re: Question about the Code in btRaycastVehicle

So this code is part of calculating the suspension force for the wheel. Part of the calculation is done in this code, the rest is done elsewhere (nice and confusing). The "inv" variable is basically a scaling factor for the suspension force. When the vehicle is sitting level on flat ground, inv is 1...
by lunkhound
Sat Jul 12, 2014 11:41 pm
Forum: General Bullet Physics Support and Feedback
Topic: My custom patch for collision callback events
Replies: 23
Views: 19988

Re: My custom patch for collision callback events

Why has this not been included in bullet's main line? If I had to guess, I'd say it's because it doesn't add anything you can't already do, and it's bad for performance. I prefer to walk the list of persistent manifolds after each simulation step, and batch up events to send out to my game objects ...
by lunkhound
Fri Nov 22, 2013 3:32 am
Forum: General Bullet Physics Support and Feedback
Topic: Sphere penerating triangle collision mesh
Replies: 2
Views: 3090

Re: Sphere penerating triangle collision mesh

To fix the objects penetrating your static meshes you could try using CCD (continuous collision detection). See bullet/Demos/CcdPhysicsDemo/CcdPhysicsDemo.cpp for an example.
However, I think you'll find that other problems will crop up if you go down the road of large, variable-sized fixedTimeSteps.