Real-Time Physics Simulation Forum

Hi, So you basically want a custom kind of gravity so that an object is attracted inverse to the surface normal? What is it attracted by when it is not in contact with another object? You have to apply custom forces to your rigidbodies in the direction you want your gravity. But first you need to de...

Oh ok, thank you! I was expecting something like that after a while. What is the reasoning for enabling them by default? Is this just meant to actively keep up the current robot pose when not changing anything?

Apparently it is not the model, it is that every multibody somehow is very rigid by default. I experienced the same with the loaded nao robot.

Hello, I know that this is a pretty exotic question for the bullet physics forum, but I still give it a try. I am working on a cartpole model for reinforcement learning with pybullet, so the model is built in urdf. The model looks all well but the joint between the cart and the pole somehow is fixed...

Hi, I do not think that you can define a local axis, I think you will have to update it through all reference frames. Regarding that question, does my ReferenceFrameHelper help you in any way? https://github.com/bulletphysics/bullet3/blob/master/examples/Utils/b3ReferenceFrameHelper.hpp It can conve...

No, I mean this example consisting of multiple pendula, basically you only want one, that is a parameter of the example.

https://github.com/bulletphysics/bullet ... Cradle.cpp

Hi,

Rendering questions such as this one are probably more suited to be in an opengl forum. What you could try is to find out how the bullet example browser draws them, as it uses opengl as well and draws all primitives.

Hello skosh2,

Have you seen my pendulum example in the bullet example browser? There you can find a properly swinging pendulum, which is the final product of what you based some of your code on.

Acts like what? I am not sure how it will react, it has never been done. But I am pretty sure that both games do not use a real aerodynamics model. And if they do, that is not what bullet can do for you.

Do you need a real parachute simulation or just something that looks like a parachute? I once created a parachute for a game just by making the parachute model fall to the ground slowly and make it tilt in an arbitrary direction in a sinusoidal motion. Looks pretty good if you just want to drop boxe...

For the moment, everything you can do is loading objects via URDF. In a later version, it might be possible to build boxes and other geometry again from scratch, but for the moment, just URDF is supported.

Reduce the weight ratio would be my first advice. These sometimes mess up simulations. Other than that, you can maybe reduce your simulation step so that the object do not tunnel through each other.

Hello and welcome to the forum!
Can you give us an example code segment of which vector you mean? The best documentation of how to do most things are thr examples that come with your distribution of bullet. That is where you should find simple setups of different shapes and a lot more.

Cheers

You could use the helper class I suggested and you should especially set the ERP. That tunes the amount of error that is reduced every time step. Can you give us a video of what is happening?

Hello, Do you really need the spherical joints? Maybe you could replace some of them with hinge joints approximating the most important axis of movement. Otherwise, you can always add two hinge joints one after the other separated by a tiny link to get something similar to spherical. The other probl...