[cairo] Rotations with Quaternions

[cecashon at aol.com]

I added a frame clock to rotation1.c for comparison with the VeloGyro widget. Made a few additional changes so they look the same. 

https://github.com/cecashon/OrderedSetVelociRaptor/blob/master/Misc/cairo_drawings/rotation1.c

It looks like everything works fine with cairo's transforms. The quaternion rotations look stable across the reals. The quaternion rotations aren't additive with this setup but that isn't a problem with cairo_save() and cairo_restore(). You can still animate rotations without a problem.

Eric


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