btKinematicCharacterController Rotating Collision Shape and btPairCachingGhostObject Not Interpolating With Fixed Time Step

[BlueSpud]

I was trying to implement a btKinematicCharacterController with a lot of difficulty until I figured out the up vector is oddly set to (1.0, 0.0, 0.0) by default and it should probably be (0.0, 1.0, 0.0). Even after I figured that out, there were still some issues with it.

1. The collision shape is rotated, even when changing the up vector. I've tried with both capsule and cylinder, but the x direction seems to be the taller direction

2. btPairCachingGhostObject doesn't interpolate, so its forced me to stop using my fixed timestep for physics. It doesn't use a motion state, and therefore doesn't use interpolation. It does have a getInterpolationWorldTransform() but that seems to return an identity transform.

3. When calling jump, the position of the ghost body will become (nan, nan, nan)

I would patch these myself, but I'm not familiar with the Bullet code-base at all.