Search found 229 matches

by pico
Wed Dec 05, 2018 7:46 am
Forum: General Bullet Physics Support and Feedback
Topic: Performance problems
Replies: 2
Views: 129

Re: Performance problems

Hi,

Bullet in debug mode can slow down a lot (like 800% slower in some of my cases).
Try release mode to see if there is really a performance penalty.
by pico
Tue Oct 24, 2017 2:04 pm
Forum: General Bullet Physics Support and Feedback
Topic: How can I detect collisions between soft and rigid bodies?
Replies: 3
Views: 1978

Re: How can I detect collisions between soft and rigid bodie

Hi, you can iterate over the softbody/rigidbody contacts like this (for instance from the Tick callback) auto &array=btSoftRigidDynamicsWorld->getSoftBodyArray(); for (int j=0,size=array.size();j<size;j++) { auto &b=array[j]; for(int i=0,ni=b->m_rcontacts.size();i<ni;++i) { const btSoftBody::RContac...
by pico
Tue Jul 09, 2013 6:56 am
Forum: General Bullet Physics Support and Feedback
Topic: setLocalScaling bug when scaling a shape
Replies: 6
Views: 3093

Re: setLocalScaling bug when scaling a shape

You might be right about the character controller, but this shouldn't happen, right?[/quote] When a Rigid Body is dynamically scaled it's no more a Rigid Body, so i wouldn't expect it to work. What should happen with the contacts anyway? Should they move with scaling? Should they introduce friction?...
by pico
Sun Jul 07, 2013 7:33 pm
Forum: General Bullet Physics Support and Feedback
Topic: setLocalScaling bug when scaling a shape
Replies: 6
Views: 3093

Re: setLocalScaling bug when scaling a shape

Hi, i guess scaling doesn't invalidate the manifold cache as dynamic scaling is is not a property of Rigid Body Simulation. In general, if you want to make a Mario64 like game you need to use a custom character controller (CC). Otherwise you run into a lot of problems you can't solve in Bullet Rigid...
by pico
Sat Mar 09, 2013 5:11 pm
Forum: General Bullet Physics Support and Feedback
Topic: Performance optimisation for cubes - what to expect:mobile
Replies: 1
Views: 1330

Re: Performance optimisation for cubes - what to expect:mobi

Hi,

you can test using the box/box collision algorithm instead of the generic GJK one.
The examples have code how to do this.
by pico
Sun Mar 03, 2013 2:22 pm
Forum: Applications, Games, Demos or Movies using Bullet
Topic: Looking for performance guidelines for my use case
Replies: 1
Views: 2387

Re: Looking for performance guidelines for my use case

Hi, one important factor is that Bullets CPU usage grows linearly with the number of collision bodies, even if they are asleep or static. On low-end handheld gaming machines you can so easily spend a few milliseconds when you just have a few hundred static objects without any collision response at a...
by pico
Sat Aug 11, 2012 1:12 pm
Forum: General Bullet Physics Support and Feedback
Topic: Bumpy Character Movement
Replies: 5
Views: 2314

Re: Bumpy Character Movement

Hi,

each triangle in a mesh is treated by bullet like a seperate entity which causes such problems.
You can use the 'btTriangleInfoMap' to generate connectivity information and remove internal triangle edges based on certain heuristics. There are a few threads about such problems here in the forum.
by pico
Mon May 28, 2012 7:03 pm
Forum: General Bullet Physics Support and Feedback
Topic: Major contact stability improvement
Replies: 57
Views: 21179

Re: Major contact stability improvement

Hi Laurent, thanks for your work. I would suggest to post such issues/patches here: http://code.google.com/p/bullet/issues/list So you can make sure Erwin actually notices them and integrates them into the main branch when possible. (posted again in http://www.bulletphysics.org/Bullet/phpBB3/viewtop...
by pico
Mon May 28, 2012 7:02 pm
Forum: General Bullet Physics Support and Feedback
Topic: Sphere Box collisions
Replies: 4
Views: 3627

Re: Sphere Box collisions

Hi Laurent,

thanks for your work.

I would suggest to post such issues/patches here:
http://code.google.com/p/bullet/issues/list

So you can make sure Erwin actually notices them and integrates them into the main branch when possible.
by pico
Sun Jan 08, 2012 3:23 pm
Forum: General Bullet Physics Support and Feedback
Topic: Bug: btAxisSweep3 causes overlap false positives with Ghosts
Replies: 3
Views: 1521

Re: Bug: btAxisSweep3 causes overlap false positives with Gh

In my experience, the fastest way to get Bullet issues fixed is to create a repro case based on the basic bullet demo
and upload it along with an issue description here:
http://code.google.com/p/bullet/issues/list

Otherwise bugs get often overlooked or simply forgotten.
by pico
Thu Mar 10, 2011 9:11 am
Forum: General Bullet Physics Support and Feedback
Topic: Many static objects
Replies: 6
Views: 2435

Re: Many static objects

The island recalculation time seems to be the issue in the thread i mentioned above. Don't care about that threaad. I've taken a look at the source and the island recalc issue for statics is already fixed. However, Bullet currently still needs to go through all bodies for certain task and so this c...
by pico
Thu Mar 10, 2011 8:47 am
Forum: General Bullet Physics Support and Feedback
Topic: Many static objects
Replies: 6
Views: 2435

Re: Many static objects

[quote="NaN"]Turns out that I've missed to setActivationState(DISABLE_SIMULATION) for my static objects. After applying it the results look much better. Though there is still the overhead of simulation island recalculation and isActive() check for all collision objects. Hi, thats right due to the up...
by pico
Sun Feb 27, 2011 8:37 am
Forum: General Bullet Physics Support and Feedback
Topic: sphere-sphere collision when inside each other
Replies: 4
Views: 1134

Re: sphere-sphere collision when inside each other

bump how can I make sure the collision detection threads spheres as intersecting if one is inside the other? Hi, volumes should detect intersection, even when they are inside eachothers. If you can reproduce the problem in one of the bullet demos you may want to create an issue: http://code.google....
by pico
Sun Feb 27, 2011 8:17 am
Forum: General Bullet Physics Support and Feedback
Topic: Many static objects
Replies: 6
Views: 2435

Re: Many static objects

Hi, thanks for your patch. However, i don't think the current (non compound) scenario is right. UpdateAABBs cpu usage should not grow linear with the number of static items in the world (at least when setForceUpdateAllAabbs is false). Maybe something got broke in a bullet update? You may want to che...
by pico
Fri Dec 24, 2010 12:42 pm
Forum: General Bullet Physics Support and Feedback
Topic: setWorldTransform to move btRigidBody does not work
Replies: 4
Views: 3167

Re: setWorldTransform to move btRigidBody does not work

You can try to use a Kinematic body if you want to udpate the position frequently.
Another option is to call "UpdateSingleAabb" from the btDiscreteDynamicsWorld (after you changed the transform).