Search found 78 matches

by Nathanael
Fri Aug 29, 2008 3:01 am
Forum: General Bullet Physics Support and Feedback
Topic: Drawing rope
Replies: 4
Views: 2081

Re: Drawing rope

I did see the thread about softbodies and OGRE and kind of figured I had to go through the nodes/faces to render. The number of faces for rope is always zero (but that is probably expected since none are passed in when creating). Nodes as far as I can tell is the anchor point to each piece of the r...
by Nathanael
Thu Aug 28, 2008 1:10 pm
Forum: General Bullet Physics Support and Feedback
Topic: Drawing rope
Replies: 4
Views: 2081

Re: Drawing rope

Here's a code snippet to 'parse' soft bodies for rendering purposes, given your btSoftRigidWorld* as "world": /* Dummy 'graphic driver' */ struct { void DrawPoint(const btVector3&) {} void DrawLine(const btVector3&,const btVector3&) {} void DrawTriangle(const btVector3&,const btVector3&,const btVect...
by Nathanael
Thu Aug 28, 2008 1:50 am
Forum: General Bullet Physics Support and Feedback
Topic: btGjkEpaSolver2 error
Replies: 6
Views: 2651

Re: btGjkEpaSolver2 error

You have to provide more information and/or code sample to reproduce the problem.
by Nathanael
Sun Aug 24, 2008 4:57 am
Forum: General Bullet Physics Support and Feedback
Topic: Self-collision
Replies: 1
Views: 1084

Re: Self-collision

No self collisions yet sorry.

Nathanael.
by Nathanael
Sun Aug 10, 2008 4:54 am
Forum: General Bullet Physics Support and Feedback
Topic: Performance issue adding objects when using btDbvtBroadphase
Replies: 2
Views: 1448

Re: Performance issue adding objects when using btDbvtBroadphase

Whenever I stream in new objects and insert them to the collision system I get a noticable hitch (sometimes as long as a quarter to half second). The objects come in groups of a few dozen at a time. half a second!!? that's eternity, i know peoples that use dbvt to spawn particles in their world, we...
by Nathanael
Fri Aug 08, 2008 10:30 am
Forum: General Bullet Physics Support and Feedback
Topic: Instability during collision between two softbodies
Replies: 2
Views: 1520

Re: Instability during collision between two softbodies

You cannot use cluster collision on 1d soft bodies, for best results, try to model volumetric ropes with soft bodies, or better still, rigid bodies connected by constraints. Don't forget that currently, collision detection is discreet, so thinner your shape is, more likely it is to miss collisions, ...
by Nathanael
Fri Aug 08, 2008 10:22 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Soft bodies early preview
Replies: 41
Views: 25128

Re: Soft bodies early preview

That's shape matching, you can take a look at 'Init_BunnyMatch' and 'Init_TorusMatch' methods in SoftDemo.cpp.

Nathanael.
by Nathanael
Sat Aug 02, 2008 3:07 am
Forum: General Bullet Physics Support and Feedback
Topic: About btDbvtBroadphase and other approaches
Replies: 2
Views: 2255

Re: About btDbvtBroadphase and other approaches

Compared to SAP, here's a short pro/con list: Pros: - Fast insertion, removal, update. - Unbounded world space. - Additional queries support: Ray-casting, Culling, Occlusion, LOD, etc... - One data structure for physics and everything else in a game engine. Cons: - Lot of cache misses compared to SA...
by Nathanael
Thu Jul 24, 2008 2:47 am
Forum: General Bullet Physics Support and Feedback
Topic: btDbvtBroadphase::performDiscreteCollisionDetection() perf?
Replies: 5
Views: 2283

Re: btDbvtBroadphase::performDiscreteCollisionDetection() perf?

Humm, if you have time, can you post timings of btDbvtBroadphase and btSweepAxis ? and if possible a more detailed profiling output, i'd like to get to the bottom of this.
Did you called btDbvtBroadphase optimize after your static world creation?

Nathanael.

btw, FreeRealms like very nice.
by Nathanael
Wed Jul 23, 2008 2:21 am
Forum: General Bullet Physics Support and Feedback
Topic: btDbvtBroadphase::performDiscreteCollisionDetection() perf?
Replies: 5
Views: 2283

Re: btDbvtBroadphase::performDiscreteCollisionDetection() perf?

Ok, here's a quick work around, if after your objects creation you call myrigidbody->setActivationState(ISLAND_SLEEPING); that should fix the issue. In the upcoming version (2.70), btDbvtBroadphase is optimized for your use case, and add the following method: bDbvttBroadphase::optimize() to be calle...
by Nathanael
Wed Jul 23, 2008 12:53 am
Forum: General Bullet Physics Support and Feedback
Topic: btDbvtBroadphase::performDiscreteCollisionDetection() perf?
Replies: 5
Views: 2283

Re: btDbvtBroadphase::performDiscreteCollisionDetection() perf?

Can you provide a reproduction case ?

Thanks for the feedback,
Nathanael.
by Nathanael
Mon Jul 21, 2008 3:04 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: b-spline evaluation near t=1
Replies: 1
Views: 1398

Re: b-spline evaluation near t=1

I think your basis functions should be of degree 3 ('num knots'-'num cp'-1), if the curve you expect is a "classic" Bezier like, your knots vector should be {0,0,0,0,1,1,1,1}, be careful to handle divide by zero == 0. If you look for a library, the best that i know of is http://libnurbs.sourceforge....
by Nathanael
Mon Jul 21, 2008 1:26 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Broad Phase with spheres
Replies: 2
Views: 1442

Re: Broad Phase with spheres

I guess SAP could do just fine, else you can try to google papers about "smooth particle hydrodynamic" which is a Lagrangian method to simulate fluid that require just that, very fast enumeration of interacting particles (usually fixed radius). You can try Takashi Amada SPH demo http://www.ss.iij4u....
by Nathanael
Fri Jul 18, 2008 11:36 am
Forum: General Bullet Physics Support and Feedback
Topic: Minimal effort for (deterministic) state rewind
Replies: 4
Views: 3011

Re: Minimal effort for state rewind

Sorry I can't be of any more help, but some peoples had similar problem in the past, they may be able to help, try starting a new thread including 'deterministic results' in the topic :wink: .

Good luck,
Nathanael.
by Nathanael
Fri Jul 18, 2008 11:29 am
Forum: General Bullet Physics Support and Feedback
Topic: Rope and SoftBody
Replies: 2
Views: 1621

Re: Rope and SoftBody

You need to enable soft/soft collision detection (disable by default), so for each one of your soft bodies: mybody->m_cfg.collisions |= btSoftBody::fCollision::VF_SS; Collision handling between soft bodies are not especially well handled yet, (vertex/face only), so you may have to tessellate quit a ...