1 #ifndef __TRACKBALL_H__
2 #define __TRACKBALL_H__
4 * (c) Copyright 1993, 1994, Silicon Graphics, Inc.
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37 * OpenGL(TM) is a trademark of Silicon Graphics, Inc.
41 * A virtual trackball implementation
42 * Written by Gavin Bell for Silicon Graphics, November 1988.
48 * Pass the x and y coordinates of the last and current positions of
49 * the mouse, scaled so they are from (-1.0 ... 1.0).
51 * The resulting rotation is returned as a quaternion rotation in the
55 trackball(Quaternion *a, double p1x, double p1y, double p2x, double p2y);
58 * This function computes a quaternion based on an axis (defined by
59 * the given vector) and an angle about which to rotate. The angle is
60 * expressed in radians. The result is put into the third argument.
63 axis_to_quat(Vector *a, double phi, Quaternion *q);