type quat 

(* 
 * return a unit quaternion
 *)
val unit_quat: unit -> quat

(*
 * 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 
 *)

val trackball: p1:(float*float) -> p2:(float*float) -> quat

(*
 * 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.  
 *)
(* quaternion multiplication -ijt *)
val add_quats: q1:quat -> q2:quat -> quat

(*
 * A useful function  builds a rotation matrix based on given quaternion.
 *)
val build_rotmatrix: q:quat -> GlMat.t

(*
 * 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.  
 *)
val axis_to_quat: axis:Gl.vect3 -> phi:float -> quat 



(*
 * (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.
 *)
(*
 * trackball.h
 * A virtual trackball implementation
 * Written by Gavin Bell for Silicon Graphics  November 1988.
 *)

(* Ported to lablglut by Issac Trotts on Sun Aug 11 2002. *)

