Search found 28 matches

by Dani3L
Wed Jul 15, 2015 6:43 am
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: ReactPhysics3D - 3D Physics engine in C++
Replies: 2
Views: 38346

Re: ReactPhysics3D - 3D Physics engine in C++

I am not a big expert in Bullet but currently the main differences I see is that ReactPhysics3D does not support Triangular Meshes (I'm working on it), Continuous Collision Detection and Soft bodies.

Best regards
by Dani3L
Wed Apr 08, 2015 9:00 am
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: My 2015 links
Replies: 3
Views: 35314

Re: My 2015 links

Thanks a lot Pierre for releasing the code of PEEL.
I also think that an official repository would be a good idea.

-----------------------
Daniel Chappuis
Switzerland
by Dani3L
Wed Mar 25, 2015 10:08 pm
Forum: Links, Papers, Libraries, Demos, Movies, Comparisons
Topic: ReactPhysics3D - 3D Physics engine in C++
Replies: 2
Views: 38346

ReactPhysics3D - 3D Physics engine in C++

Hi everyone, I have been around on this forum for quite a while to learn about physics programming. I think it's now time to also share something. This is the project I am working on for some time now. It is called ReactPhysics3D. ReactPhysics3D is an open source 3D physics engine library written in...
by Dani3L
Wed Nov 13, 2013 7:16 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Constraints Derivation for Rigid Body Simulation in 3D
Replies: 2
Views: 9806

Re: Constraints Derivation for Rigid Body Simulation in 3D

I noticed that your slider joint contains the Jacobian of: [-t, -((r1 + u) x t), t, (r2 x t)] Although a valid jacobian one body is not getting any recognition of the u vector. Since the angular terms aren't symmetric the Jacobian is basically assuming that one of the bodies doesn't change orientat...
by Dani3L
Tue Nov 12, 2013 10:52 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Constraints Derivation for Rigid Body Simulation in 3D
Replies: 2
Views: 9806

Constraints Derivation for Rigid Body Simulation in 3D

Hello. I have been using this forum for many years now and I have learned so many things here. Now, it's my turn to share. During the development of my 3D physics library, I had to model different constraints like contacts, friction and some joints between rigid bodies. I'm using a Sequential Impuls...
by Dani3L
Wed May 29, 2013 6:33 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Hinge constraint
Replies: 11
Views: 18448

Re: Hinge constraint

Ok thanks. For the moment I solve a block for the linear constraints and another block for the angular constraints. So at most, I have to solve a 3x3 system. I handle the limits and motor separately. If you run a block solver on a mechanic system like a ragdoll I somewhere read years ago that this i...
by Dani3L
Tue May 28, 2013 9:46 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Hinge constraint
Replies: 11
Views: 18448

Re: Hinge constraint

Thanks for your answer Dirk ! When you say : The usual problem is that the linear and angular constraints are fighting each other. We have this issue in both situations (solving the constraints by block or individually) right ? I have read that in some situations, it is better to solve the constrain...
by Dani3L
Mon May 27, 2013 9:57 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Hinge constraint
Replies: 11
Views: 18448

Re: Hinge constraint

Dirk Gregorius wrote:Note that for solving this you handle each constraint separately. So for a hinge I would suggest solving C1 followed by C2 and finally solve a 3x3 point-to-point constraint.
Why is it better to solve the two constraints separately and not at the same time where K would be a 2x2 matrix ?
by Dani3L
Thu Jan 03, 2013 10:11 am
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: Multiplication by time step in Sequential Impulses
Replies: 4
Views: 9755

Multiplication by time step in Sequential Impulses

Hello, I am studying the Sequential Impulse theory for rigid bodies simulation using the slides of Erin Catto from GDC 2009 . At the slide 52, it is written that the impulse P is equal to the Force F times the time step h : P = h F with the force : F = J^T lambda Then, at slide 53, it is written tha...
by Dani3L
Sun Dec 02, 2012 7:11 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: How is the Persistent Manifold Area computed in Bullet ?
Replies: 4
Views: 9126

Re: How is the Persistent Manifold Area computed in Bullet ?

Thanks a lot for your answer, I didn't know this formula. According to the Wikipedia page, this formula is used to compute the area of a convex quadrilateral ABCD using the cross product AC^BD where AC and BD are the two diagonals of the quadrilateral. However, I am not sure I understand why we are ...
by Dani3L
Fri Nov 30, 2012 12:46 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: How is the Persistent Manifold Area computed in Bullet ?
Replies: 4
Views: 9126

How is the Persistent Manifold Area computed in Bullet ?

Hello, I am studying the implementation of the persistent contact manifold in Bullet in the file btPersistentManifold.cpp . At some point, if the contact cache is full, we want to keep the new contact point, the contact point with the deepest penetration depth and then, we choose the points that max...
by Dani3L
Sun Aug 08, 2010 6:09 pm
Forum: Research and development discussion about Collision Detection and Physics Simulation
Topic: General strategie of a physics engine for contact generation
Replies: 4
Views: 5799

Re: General strategie of a physics engine for contact genera

Ok thank you very much for your answer. There is something I don't understand : Why bullet uses both alternatives. For instance bullet uses GJK algorithm (alternative 1) but also a special box-box collision algorithm (alternative 2). Why ? Is it possible to use only GJK algorithm to compute the cont...