Khronos public bugtracker – Bug 217
kinematics should allow true spherical joint
Last modified: 2014-01-07 10:23:11 PST
There is a difference between a true spherical joint and a compound joint that has three stacked orthogonal revolute axes: the latter can be gimbal locked but the former cannot. It appears that only the latter can currently be expressed in the 1.5 joint schema. It would be useful to also allow true spherical joints.
Even though extra elements are currently permitted as children of the joint element, there does not appear to be a clean way to use this mechanism to specify a spherical joint, because at least one revolute or prismatic element must also be a child of every joint element.