[PyOpenGL-Users] arcball.py: arcball rotation widget

[Maciej K. <ma...@dg...>]

I've made available an implementation of the arcball method of rotation.
     http://www.dgp.toronto.edu/~mac/code-n-patches/
Perhaps it might be useful to someone.

,----
| arcball.py: defines a subclass of 'Opengl' that supports the use of
| arcball method of rotation, which is frequently used in the graphics
| field. Run the script to see a very rough and quick demo. You'll
| probably want to bring up a different pyopengl app to compare the
| rotation methods.
| 
| Arcball summary: one of the main benefits is that it has no hysterisis:
| once you start dragging out a rotate, coming back to the same spot with
| the mouse cursor always gives the same rotation, no matter what path was
| taken to get the cursor to that spot. Also, if you drag the rotation
| outside the ball's perimeter (alas, it is currently not drawn; it's on
| the TODO), the axis of rotation is perpendicular to the
| screen/projection surface.
`----

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