How to make a model for Bullet?

[meclory]

Hi,

I want to make a dynamic simulator using Bullet. I think that the first thing to do is to constitute mechanism models to be analyzed by Bullet. What will be the best way(or tool) to constitute such models? Please let me know some methods.

Thank you very much~!

[Wavesonics]

I believe what you want is Blender (http://www.blender.org/). Bullet started out as blender's physics extension, and Bullet can save and load physics data in the COLLADA (http://www.collada.org/) format which blender can save and load as well.

[meclory]

Thank you very much !

So, we can constitute a mechanism using mechanical primitives (such as spring, damper, mass, various joints, and so on...) in the Blender tool? Then the next thing is to make a code using Bullet C/C++ API which can :
1. load the model
2. change values of parameters which are related to the degree-of-freedom.
3. render the simulation using OpenGL or something

How about this process? Is it feasible?

[Erwin Coumans]

So, we can constitute a mechanism using mechanical primitives (such as spring, damper, mass, various joints, and so on...) in the Blender tool? Then the next thing is to make a code using Bullet C/C++ API which can :
1. load the model
2. change values of parameters which are related to the degree-of-freedom.

There are various ways to load models, the best supported method is using the COLLADA .dae importer, using Extras/BulletColladaConverter. BulletColladaConverter can load and save Bullet dynamics worlds, using COLLADA DOM and libxml (both are included in the Bullet sources in the Extras folder) . See ColladaDemo how to use this. It handles import of collision shapes, rigid body information (mass, friction etc) and constraints.

3. render the simulation using OpenGL or something

Bullet doesn't deal with graphics, that is up to the user.

Hope this helps,
Erwin

Bullet started out as blender's physics extension

No, a predecessor of Bullet started as a physics engine for a PlayStation 2 game. Then the code was cleaned up and evolved into open source. After it went open source, it was integrated into Blender and other applications and commercial games.

[Wavesonics]

No, a predecessor of Bullet started as a physics engine for a PlayStation 2 game. Then the code was cleaned up and evolved into open source. After it went open source, it was integrated into Blender and other applications and commercial games.

Oh thats cool, i had no idea it had a past before Blender!