This code example shows interpolation between a set of four points using piecewise 
Hermite interpolation.  In this case, the Hermite curve is set up automatically using
the clamped spline method, a natural spline, a cyclic spline, or an acyclic spline.
The orange curve shows the Hermite path, the red points the interpolating points, 
the yellow lines the tangents (incoming and outgoing) at each point.

Controls
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ESC: quit
m: toggle between spline types
SPACE: reset/stop animation
