libigl_Martin/examples/scene-rotation

This is a small program that demonstrates various 2D mouse input interfaces for
control a 3D world-in-hand rotation.

So far this implements:
ROTATION_TYPE_IGL_TRACKBALL Continuous, "wrap-around" trackball, as seen in
AntTweakBar.
ROTATION_TYPE_BELL_TRACKBALL De facto "Standard" trackball, limited to 180°
rotations.
ROTATION_TYPE_TWO_AXIS_VALUATOR Rotate around drag vector by amount
proportional to drag length.
ROTATION_TYPE_TWO_AXIS_VALUATOR_FIXED_UP Rotate around fixed up-vector by x
drag length and around y drag vector by y drag length. As seen in Maya, 3D
Studio Max, etc.

More trackball variantes could be snatched from here:
http://opentissue.org/svn/OpenTissue/archieve/grid3d/OpenTissue/trackball/