On Tue, 23 Jul 2013 15:11:43 +0200, Peter Otten wrote: > The conversion to int introduces a rounding error that accumulates over > time.
Most floating point calculations introduce a rounding error. If the calculations are iterated, the error will accumulate. In general, you want to avoid accumulating entire transformations. E.g. if you want a spinning object, maintain the cumulative rotation angle and rotate the original points each frame. If you must accumulate transformations, you need to actively work to maintain any desired invariants. E.g. if a transformation is supposed to be orthonormal (all axes perpendicular and of unit length), you should renormalise it periodically, otherwise the lengths and angles will change over time. -- http://mail.python.org/mailman/listinfo/python-list