quat_slerp - Version of quat_interpolate() allowing control over the rotation.
Allegro game programming library.
#include <allegro.h>
void quat_slerp(const QUAT *from, const QUAT *to, float t, QUAT
*out, int how);
The same as quat_interpolate(), but allows more control over how the rotation is
done. The how parameter can be any one of the values:
QUAT_SHORT - like quat_interpolate(), use shortest path
QUAT_LONG - rotation will be greater than 180 degrees
QUAT_CW - rotate clockwise when viewed from above
QUAT_CCW - rotate counterclockwise when viewed from above
QUAT_USER - the quaternions are interpolated exactly as
given