Continuing the discussion from Lock Z axis:
Some people tried to lock an axis to make theirs game “2D” but they had to do a workaround (see above), because these methods wasn’t available in the bullet native wrapping :
rigidBody.setLinearFactor( new Vector3f(1,1,0)); rigidBody.setAngularFactor( new Vector3f(0,0,1));
So i added those methods into the bullet warping also thanks to @normen who explained how to make such change.
The problem is that these methods aren’t available for jBullet.
Edit : those changes are merged into 3.1