Search found 4092 matches

by Erwin Coumans
Wed May 09, 2018 12:54 am
Forum: General Bullet Physics Support and Feedback
Topic: stepSimulation freezes for large number of multi body objects.
Replies: 2
Views: 158

Re: stepSimulation freezes for large number of multi body objects.

Is this C++ or PyBullet? You should be able to profile timings and gradually increase the number of robots.

We are not clearvoyant: try to file an issue in the tracker and provide a simple reproduction case.

https://github.com/bulletphysics/bullet3/issues
by Erwin Coumans
Thu May 03, 2018 2:56 pm
Forum: General Bullet Physics Support and Feedback
Topic: CPU multithreading is working!
Replies: 145
Views: 42830

Re: CPU multithreading is working!

Thanks for the reply. Can you report the issue in the Bullet https://github.com/bulletphysics/bullet3/issues tracker, so we can track progress on fixes? 1. My program using single-threaded btDiscreteDynamicsWorld crashed because of btSequentialImpulseConstraintSolver::getOrInitSolverBody method retu...
by Erwin Coumans
Thu May 03, 2018 2:52 pm
Forum: General Bullet Physics Support and Feedback
Topic: Maximum angular velocity
Replies: 2
Views: 114

Re: Maximum angular velocity

You can override the maximum angular velocity using btMultiBody::setMaxCoordinateVelocity

This maximum velocity is a safety mechanism, to avoid energies going to infinity.

What are you trying to achieve with a very high velocity?
by Erwin Coumans
Thu May 03, 2018 1:38 pm
Forum: General Bullet Physics Support and Feedback
Topic: Is diagonlize/extractRotation broken, i.e., does nothing? see 3 lines of example code and try yourself
Replies: 3
Views: 100

Re: Is diagonlize/extractRotation broken, i.e., does nothing? see 3 lines of example code and try yourself

The original btMatrix3x3::diagonalize method should work for symmetric matrices. Recently (2017) I replaced it with a diagonalize method based on the "A Robust Method to Extract the Rotational Part of Deformations" paper and its extractRotation implementation, but the resulting rotation still includ...
by Erwin Coumans
Thu May 03, 2018 1:26 pm
Forum: General Bullet Physics Support and Feedback
Topic: Someone familiar with btMultiBody please let me know if this is correct.
Replies: 2
Views: 153

Re: Someone familiar with btMultiBody please let me know if this is correct.

I strongly recommend first using the PyBullet Python bindings, and loading URDF or SDF files, it is documented in the https://docs.google.com/document/d/10sXEhzFRSnvFcl3XxNGhnD4N2SedqwdAvK3dsihxVUA/edit#heading=h.2ye70wns7io3 . Our recent RSS paper (Sim-to-Real: Learning Agile Locomotion For Quadrup...
by Erwin Coumans
Wed Apr 11, 2018 7:14 am
Forum: PyBullet Support and Feedback
Topic: pyBullet vs Gazebo
Replies: 3
Views: 349

Re: pyBullet vs Gazebo

Ultimately you can try out both and decide for yourself. It seems that Gazebo uses Bullet Gazebo uses btRigidBody from Bullet (maximal coordinate rigid bodies) which is not necessary the best way for robotics, it allows for joint gap. PyBullet uses Featherstone articulated rigid bodies (btMultiBody)...
by Erwin Coumans
Thu Mar 15, 2018 3:00 pm
Forum: General Bullet Physics Support and Feedback
Topic: [SOLVED] Updating CollisionShape leads to undetected collisions
Replies: 2
Views: 210

Re: [SOLVED] Updating CollisionShape leads to undetected collisions

Halfextents needs to be positive values (and sphere radius too etc). Negative mass is also not supported.

In addition, if you make changes to collision shape, you first need to

1) remove the rigid body/collision object from the world,
2) make the changes
3) re-insert the body to the world.
by Erwin Coumans
Thu Mar 01, 2018 10:07 pm
Forum: General Bullet Physics Support and Feedback
Topic: CPU multithreading is working!
Replies: 145
Views: 42830

Re: CPU multithreading is working!

Thanks, this is very interesting. Have you experimented with graph coloring (solving a large island in parallel)?
by Erwin Coumans
Wed Feb 07, 2018 3:57 am
Forum: PyBullet Support and Feedback
Topic: Geometry resolution importing from URDF
Replies: 1
Views: 250

Re: Geometry resolution importing from URDF

You can use the flags=pybullet.URDF_USE_IMPLICIT_CYLINDER in loadURDF, then it uses an implicit cylinder. Alternatively, just model a tesselated cylinder in Blender (or other 3d modeler) at the resolution you like, and write it to a wavefront OBJ file and use that.
by Erwin Coumans
Wed Feb 07, 2018 3:55 am
Forum: PyBullet Support and Feedback
Topic: JBullet Basic question
Replies: 9
Views: 662

Re: JBullet Basic question

Never heard about JBullet, what is it?

This is a forum for PyBullet, the Python module, which is much more than just Python bindings for Bullet: it also adds rendering, VR, inverse kinematics, inverse dynamics, rendering (CPU and OpenGL) etc. See the PyBullet quickstart guide.
by Erwin Coumans
Wed Feb 07, 2018 3:52 am
Forum: PyBullet Support and Feedback
Topic: STATE_LOGGING_VIDEO_MP4 in DIRECT mode?
Replies: 4
Views: 279

Re: STATE_LOGGING_VIDEO_MP4 in DIRECT mode?

Indeed, STATE_LOGGING_VIDEO_MP4 is only available when using OpenGL (GUI or SHARED_MEMORY). Thinking of it, we could implement this also in DIRECT mode, using the TinyRenderer to generate images. Some people log the state of objects, and create the video/playback afterwards. Another option is to use...
by Erwin Coumans
Mon Feb 05, 2018 4:17 pm
Forum: General Bullet Physics Support and Feedback
Topic: Strong bounce on collision, is this expected?
Replies: 2
Views: 279

Re: Strong bounce on collision, is this expected?

For a static plane, only a single contact is added for each simulation step (by default) causing a small amount of rotation and penetration. We don't have specialized plane versus cube and plane versus convex etc. For cube versus plane it would be trivial to add of course, but you would still have t...
by Erwin Coumans
Thu Feb 01, 2018 4:38 pm
Forum: General Bullet Physics Support and Feedback
Topic: rigid bodies violently jumping away
Replies: 8
Views: 628

Re: rigid bodies violently jumping away

Please file a very simple PyBullet repro case and use the github issue tracker.

Keep it simple, no Blender, just plain PyBullet.

Also check out the PyBullet Quickstart Guide and examples and try to understand why the PyBullet examples work fine and your setup doesn't.
by Erwin Coumans
Thu Feb 01, 2018 6:40 am
Forum: General Bullet Physics Support and Feedback
Topic: Way to get softbody render from p.getCameraImage?
Replies: 2
Views: 214

Re: Way to get softbody render from p.getCameraImage?

This is not implemented yet, soft body in PyBullet is very preliminary.
by Erwin Coumans
Thu Jan 25, 2018 6:02 am
Forum: PyBullet Support and Feedback
Topic: Collision Resolution
Replies: 2
Views: 318

Re: Collision Resolution

There are a few ways to keep simulation in 2D indeed: you can use a 'fixed' base and add joints that allow motion in 2D. Look at the Gym environments 'Hopper' and 'HalfCheetah' and 'Walker2D', they only move in the 2D plane. https://github.com/bulletphysics/bullet3/blob/master/examples/pybullet/gym/...