* (c) Copyright 1993, 1994, Silicon Graphics, Inc.
* ALL RIGHTS RESERVED
* Permission to use, copy, modify, and distribute this software for
* any purpose and without fee is hereby granted, provided that the above
* copyright notice appear in all copies and that both the copyright notice
* and this permission notice appear in supporting documentation, and that
* the name of Silicon Graphics, Inc. not be used in advertising
* or publicity pertaining to distribution of the software without specific,
* written prior permission.
* THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
* AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
* FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON
* GRAPHICS, INC. BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
* SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
* KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
* LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
* THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC. HAS BEEN
* ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
* POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
* US Government Users Restricted Rights
* Use, duplication, or disclosure by the Government is subject to
* restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
* (c)(1)(ii) of the Rights in Technical Data and Computer Software
* clause at DFARS 252.227-7013 and/or in similar or successor
* clauses in the FAR or the DOD or NASA FAR Supplement.
* Unpublished-- rights reserved under the copyright laws of the
* United States. Contractor/manufacturer is Silicon Graphics,
* Inc., 2011 N. Shoreline Blvd., Mountain View, CA 94039-7311.
* OpenGL(TM) is a trademark of Silicon Graphics, Inc.
* A virtual trackball implementation
* Written by Gavin Bell for Silicon Graphics, November 1988.
* Pass the x and y coordinates of the last and current positions of
* the mouse, scaled so they are from (-1.0 ... 1.0).
* The resulting rotation is returned as a quaternion rotation in the
* first paramater.
gfs_gl_trackball(float q, float p1x, float p1y, float p2x, float p2y);
* Given two quaternions, add them together to get a third quaternion.
* Adding quaternions to get a compound rotation is analagous to adding
* translations to get a compound translation. When incrementally
* adding rotations, the first argument here should be the new
* rotation, the second and third the total rotation (which will be
* over-written with the resulting new total rotation).
gfs_gl_add_quats(float *q1, float *q2, float *dest);
* A useful function, builds a rotation matrix in Matrix based on
* given quaternion.
gfs_gl_build_rotmatrix(float m, float q);
* This function computes a quaternion based on an axis (defined by
* the given vector) and an angle about which to rotate. The angle is
* expressed in radians. The result is put into the third argument.
gfs_gl_axis_to_quat(float a, float phi, float q);