Summary I can find no documentation on the frame of reference for defining the rigid body HINGE constraint Z axis rotational limits. Blender defaults these to lower = -45 deg and upper = +45 deg. Online docs provide no detail and YouTube videos invariably skip over this aspect of constraint set-up.
Can someone direct me to documentation or provide insight into how the HINGE and other RB constraints angular limits are defined. i.e. with respect to what are the limit angles defined?
Detail I need to understand the Blender set up for these constraints well, as I need to prototype before exporting into my own game engine, which also uses Bullet Physics.
I've tried a Blender demo set-up with 2 bodies, one static/passive and the other active and a HINGE between the two and just when I think I've got it, for instance assuming:
- The angles are defined looking down the constraint's local Z axis, towards the origin.
- With the limiting angles defined relative to the XZ plane.
- With +ve angles being above the XZ plane and -ve below.
But as soon as I start playing with the angles, my hypothesis falls apart.
I can even manage to provide limits that cause the joint to act against gravity in an unrealistic way.
Given the lack of online guidance on this (including Blender stack exchange) I'm starting to think that this is not a well understood area. I assume the same will apply when I come to look at the other constraint types too, especially the GENERIC constraint. So any help or direction will be gratefully appreciated.