Search found 27 matches

by tasora
Sat May 01, 2010 4:10 pm
Forum: General Bullet Physics Support and Feedback
Topic: Very small objects
Replies: 1
Views: 2436

Very small objects

hallo, I am using Bullet collision detection in my physics simulation library. Today I was trying to simulate some thousands of pebbles interacting with an off-road vehicle, and I discovered that the performance of the collision was largely affected by the scale (measuring units). Basically: if I si...
by tasora
Tue Jan 08, 2008 3:28 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: The best engine to generate close packings of spheres?
Replies: 11
Views: 6700

Re: The best engine to generate close packings of spheres?

Hallo Dirk, Some informations about the choiche of the omega overrelaxation factor. Currently I don't have an optimal algorithm for the best choiche of that factor - in most cases I prefer to keep omega=1 (although this is not guaranteed to produce a contractive mapping under all circumstances, it p...
by tasora
Wed Jan 02, 2008 10:19 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: The best engine to generate close packings of spheres?
Replies: 11
Views: 6700

Re: The best engine to generate close packings of spheres?

Hallo Erin, How would you compare this method to Bullet's sequential impulse solver? As already said in other threads, a PGS-like solver is not much different from a sequential impulse solver, under some circumstances (i.e. immediate update of variables as in GS or SOR schemes, etc.). Anyway, our it...
by tasora
Sun Dec 23, 2007 6:25 pm
Forum: General Bullet Physics Support and Feedback
Topic: Memory leaks in btDefaultCollisionConfiguration ? [solved]
Replies: 4
Views: 3147

Re: Memory leaks in btDefaultCollisionConfiguration ?

Hallo Erwin,
Can you please upgrade to Bullet 2.65, and see if the problem is still there?
Ok, in fact I upgraded to the latest release of the Bullet SDK, and the problem
with memory leaks is fixed. Perfect!

Alessandro Tasora
by tasora
Mon Dec 17, 2007 10:36 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: The best engine to generate close packings of spheres?
Replies: 11
Views: 6700

Re: The best engine to generate close packings of spheres?

Hallo, Can you elaborate what kind of changes to Bullet you've made? Just few changes. First of all, I use only the btCollisionWorld (I do not need to use also the Bullet dynamics, I have my own solver) Then, I modified the structure with the contact info (for the persistent manifold) so that it con...
by tasora
Fri Dec 14, 2007 12:51 pm
Forum: General Bullet Physics Support and Feedback
Topic: Memory leaks in btDefaultCollisionConfiguration ? [solved]
Replies: 4
Views: 3147

Re: Memory leaks in btDefaultCollisionConfiguration ?

hallo, Have you checked Bullet 2.65 beta2? Mhh.. I am using bullet-2.64-rc2 ... I just double checked this, and all memory is properly freed. You shouldn't need to make any code change. The destructor of btDefaultCollisionConfiguration does free the memory: Ok, so maybe it's my fault.. I must check ...
by tasora
Fri Dec 14, 2007 12:40 pm
Forum: General Bullet Physics Support and Feedback
Topic: Max number of colliding pairs
Replies: 2
Views: 2190

Re: Max number of colliding pairs

Hallo Erwin, thank you for pointing out this nice feature (i.e. fallback to heap allocation when pools are filled) because I thought it was a more 'basic' pool ... Really interesting! So this means that I can leave the 65k pairs limit without worrying too much about the effective number of contact p...
by tasora
Thu Dec 13, 2007 10:53 am
Forum: General Bullet Physics Support and Feedback
Topic: Max number of colliding pairs
Replies: 2
Views: 2190

Max number of colliding pairs

Hallo Erwin, looking in the btDefaultCollisionConfiguration C++ code, I see that there is a #define DEFAULT_MAX_OVERLAPPING_PAIRS 65535 and this means that the pool allocator for allocating colliding pairs is limited to that amount, and cannot be modified at configuration creation. Please have it as...
by tasora
Thu Dec 13, 2007 10:38 am
Forum: General Bullet Physics Support and Feedback
Topic: Memory leaks in btDefaultCollisionConfiguration ? [solved]
Replies: 4
Views: 3147

Memory leaks in btDefaultCollisionConfiguration ? [solved]

Hallo Erwin, I noticed that in Bullet examples (except in the Gimpact demo) the btDefaultCollisionConfiguration object is never deleted. In my code, I delete it by doing: bt_collision_configuration = new btDefaultCollisionConfiguration() bt_dispatcher = new btCollisionDispatcher(bt_collision_configu...
by tasora
Sat Dec 08, 2007 10:24 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: The best engine to generate close packings of spheres?
Replies: 11
Views: 6700

Re: The best engine to generate close packings of spheres?

Hi, I developed the chrono::engine physics engine, it is available at http://www.deltaknowledge.com/chronoengine Here we used chrono::engine to simulate dense granular flow of spheres up to 150'000 spheres, for simulating a PBR nuclear reactor. I suppose that poses a problem that it is similar to yo...
by tasora
Wed Nov 21, 2007 1:25 pm
Forum: General Bullet Physics Support and Feedback
Topic: Margins...
Replies: 0
Views: 2206

Margins...

Hallo, I'm using Bullet in my own physics engine (I mean, I use only the collision detection feature of Bullet, not the dynamics, so I simply perform CD, fetch the contacts from the manifolds and put them in my LCP solver). It already works, but I noticed that contacts are created, in most cases, wh...
by tasora
Mon Nov 12, 2007 1:28 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Funnell and tubes...
Replies: 0
Views: 1747

Funnell and tubes...

Hallo, I am embedding Bullet in my physics library (chrono::engine) and I am satisfied with the results. One application of my multibody solver is the simulation of granular flows inside reactors. The problem is.. how to simulate spheres inside funnells or large cylinders? Look to this animation as ...
by tasora
Tue Sep 04, 2007 8:46 am
Forum: Non-technical forum and license/patent discussion
Topic: Issues for new forum...
Replies: 11
Views: 15860

Re: Issues for new forum...

By the way: on my opinion, this 'blue' skin is much better than the one with yellow-orange
borders, which you tested yesterday (also, the yellow skin did not fit into my 1280pixel display
and fonts were too big - now it looks more compact and usable)
bye
Alessandro
by tasora
Wed Mar 14, 2007 1:56 pm
Forum: Applications, Games, Demos or Movies using Bullet
Topic: Maximum number of objects.: 32k limit reached...
Replies: 6
Views: 11869

Hi Erwin! funny, I was just sending you my modified copy of Sweep and Prune sourcecode, with a similar conditional switch to compile with 32 bit indices, and in fact I already made experiments with it. Just look at this simulation (which took few hours, mostly because my LCP solver used 130 steps fo...
by tasora
Thu Mar 08, 2007 2:36 pm
Forum: Applications, Games, Demos or Movies using Bullet
Topic: Maximum number of objects.: 32k limit reached...
Replies: 6
Views: 11869

In fact I am using the Bullet solver, with some modifications,
into my Chrono::Engine middleware
sorry, a typo..
I meant: 'I am using the Bullet collision detection , with some
modifications... ' , etc. etc. (not the solver, cause I use my own library)

Alessandro Tasora