quat_slerp - Version of quat_interpolate() allowing control over the rotation. Allegro game programming

       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

Allegro                                           version 4.4.3                              quat_slerp(3alleg4)

       quat_slerp  -  Version of quat_interpolate() allowing control over the rotation. Allegro game programming
       library.

#include<allegro.h>voidquat_slerp(constQUAT*from,constQUAT*to,floatt,QUAT*out,inthow);