Bullet physics compound shape

I'm trying to to create a compound shape pretty much in the same way I did in my C++ code.

1. Create three shapes (two btCylinderShape, and one btConeShape)
2. Create a compund shape using the tree individual shapes (btCompoundShape)
3. Create a rigid body btRigidBody using the compound shape passing a transformation matrix with some translation

How can it be done in blender?

AFAIK, the option in Properties view panel>Physics tab>CollisionBounds disclosure triangle>Compound has to be enabled for the three bodies, and one of them needs to be the parent, while the other two are its children.

This works prety well, but I need to add some offset too to the parent, as the picture shows, how can it be done?

Using a fourth empty body as a parent would introduce an aditional shape, that would mess the hole thing.

Is there a way to add an additional transformation to the physics shape attached to a mesh?

I'm currently using Blender v2.67b for Mac

• Would it work for your situation if you just merged the three objects into a single mesh object? – Gwen Jun 20 '13 at 21:15
• @Gwenn The body has a concave shape, and a hull makes the simulation somewhat unstable when it collides with other bodies. – rraallvv Jun 20 '13 at 21:20
• I'm not saying a convex hull, is it okay if your three objects are actually made into one object, with the exact same exterior vertices as before? – Gwen Jun 20 '13 at 21:24
• @Gwenn Yes it would't be a problem, but what collision bound would I choose for the mesh? – rraallvv Jun 20 '13 at 21:27
• What about the game engine? How would you go about doing compounding? I tried a few test and they seem to jitter and spasm a bit on the surface of an object when they're rotated. EDIT: Nevermind, the problem seems to be related to collision on other side(The floor or something) not having a collision bound. It behaves normally now. – user1183 Aug 27 '13 at 13:36