1 /* 2 * (c) Copyright 1993, 1994, Silicon Graphics, Inc. 3 * ALL RIGHTS RESERVED 4 * Permission to use, copy, modify, and distribute this software for 5 * any purpose and without fee is hereby granted, provided that the above 6 * copyright notice appear in all copies and that both the copyright notice 7 * and this permission notice appear in supporting documentation, and that 8 * the name of Silicon Graphics, Inc. not be used in advertising 9 * or publicity pertaining to distribution of the software without specific, 10 * written prior permission. 11 * 12 * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS" 13 * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE, 14 * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR 15 * FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON 16 * GRAPHICS, INC. BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT, 17 * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY 18 * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION, 19 * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF 20 * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC. HAS BEEN 21 * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON 22 * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE 23 * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE. 24 * 25 * US Government Users Restricted Rights 26 * Use, duplication, or disclosure by the Government is subject to 27 * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph 28 * (c)(1)(ii) of the Rights in Technical Data and Computer Software 29 * clause at DFARS 252.227-7013 and/or in similar or successor 30 * clauses in the FAR or the DOD or NASA FAR Supplement. 31 * Unpublished-- rights reserved under the copyright laws of the 32 * United States. Contractor/manufacturer is Silicon Graphics, 33 * Inc., 2011 N. Shoreline Blvd., Mountain View, CA 94039-7311. 34 * 35 * OpenGL(TM) is a trademark of Silicon Graphics, Inc. 36 */ 37 /* 38 * trackball.h 39 * A virtual trackball implementation 40 * Written by Gavin Bell for Silicon Graphics, November 1988. 41 */ 42 43 /* 44 * Pass the x and y coordinates of the last and current positions of 45 * the mouse, scaled so they are from (-1.0 ... 1.0). 46 * 47 * The resulting rotation is returned as a quaternion rotation in the 48 * first paramater. 49 */ 50 void trackball(float q[4], float p1x, float p1y, float p2x, float p2y); 51 52 void negate_quat(float *q, float *qn); 53 54 /* 55 * Given two quaternions, add them together to get a third quaternion. 56 * Adding quaternions to get a compound rotation is analagous to adding 57 * translations to get a compound translation. When incrementally 58 * adding rotations, the first argument here should be the new 59 * rotation, the second and third the total rotation (which will be 60 * over-written with the resulting new total rotation). 61 */ 62 void add_quats(float *q1, float *q2, float *dest); 63 64 /* 65 * A useful function, builds a rotation matrix in Matrix based on 66 * given quaternion. 67 */ 68 void build_rotmatrix(float m[4][4], const float q[4]); 69 70 /* 71 * This function computes a quaternion based on an axis (defined by 72 * the given vector) and an angle about which to rotate. The angle is 73 * expressed in radians. The result is put into the third argument. 74 */ 75 void axis_to_quat(float a[3], float phi, float q[4]); 76