Angle calculation in RotationBetweenVectors about ogl HOT 2 CLOSED

Okay, I was able to find out by myself.

I've read "The Shortest Arc Quaternion" in Game Programming Gems 1 by Stan Melax which this implementation is based on. There he states: "[...]the cross product [...] becomes small and potentially unstable when we try to normalize it[...]" and provides the solution which is numerically stable, resulting in the formulae used in the implementation of RotationBetweenVectors.

This, however, brings me to another question: The implementation provided by Stan Melax does not suggest to use case differentiations like if (cosTheta < -1 + 0.001f). So, are these really neccessary?

from ogl.

Okay, I've tried it. It really is a problem. Your code is great! Thank you. This issue is closed.

from ogl.