Here is the list of anglecode or C from 3D rad. http://www.3drad.com/Script_reference.htm I have a gravity object that affect the gravity of a character. I want to make it jump. So I need to reverse the orientation of that object (pointing down) to pointing up, a 180° rotation. Maybe I will use this in my script, but I don't know what is Quaternion iObjectOrientationSet(OBJ_X,Quaternion) Set the specified object orientation (defined as a quaternion). OBJ_X = object handle. Quaternion = orientation. NOTE: this function will only work with objects that support dynamic orientation setting, like SkinMesh, Particles, etc. Objects supporting physics do not usually work with this function. For example, you should not use this function to progressively alter the orientation of a RigidBody or a Car, to make it spin. You should use the Force object instead.

A quaternion is a structure of 4 values that allow to store any orientation in 3D. It is most useful for performing linear interpolation between two different orientation.

I can't give you any details on the math of quaternions, as I honestly don't know it myself. I never saw the need for quaternions in my own applications so I never gave myself the time to study them. However, I'm sure that you can find many articles on the subject on google.

Anyway, this question is really not related to AngelScript. I think you'd have more luck posting your questions on the 3drad forums, or even the 'Math and Physics' forum here on GameDev.net.

well, I express wrongly. The gravity object is "g-Force". That object have no gravity by itselve, it create gravity to a object.