trackball.mesa.lib

su 的源代码库

TRACKBALL - a MESA trackball 

trackball -  make a mouse simulate a trackball in a MESA graphics window
Function Prototype:
void
trackball(float q[4], float p1x, float p1y, float p2x, float p2y, float tbs);

Input:

Output:

Returns: void
 Notes:
 Trackball code:

 Implementation of a virtual trackball.
 Implemented by Gavin Bell, lots of ideas from Thant Tessman and
 the August '88 issue of Siggraph's "Computer Graphics," pp. 121-129.

 Vector manip code:

 Original code from:
 David M. Ciemiewicz, Mark Grossman, Henry Moreton, and Paul Haeberli
 Much mucking with by: Gavin Bell

Author: CWP: Zhaobo Meng, based on existing Mesa code.