Joints - alanjfs/houdini_wiki GitHub Wiki

How do you create a joint between two rigid bodies?

Houdini provides an interface over a significant portion of the Bullet API, including joints.

• Linear Constraints
• Angular Constraints

Overview

Here's an example that combines both angular and linear joints.

• joints.hip

There's too much going on to properly explain that, so give this another go. In a nutshell, it's..

• The Cone Twist Constraint Relationship
• The Soft Constraint Relationship
• Frames of Parent and Child rigid bodies, i.e. how to determine a pivot at which to constrain each of the two rigid bodies
• Constraints to animated objects

The workflow is not entirely clear. It's not clear what should come from SOP versus DOP, like forces and animation of velocity and damping. They all presumably translate into Data, which is presumably all that Bullet understands. And although you can directly affect data via DOPs, it is both harder to visualise (no individual fields for attributes of rigid bodies, like position) but also doesn't appear to be accessible from VEX.

Linear Constraints

Angular Constraints