samples/opengl/penguin/trackball.h

   1 /*
   2  * (c) Copyright 1993, 1994, Silicon Graphics, Inc.
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  14  * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
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  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
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  31  * Unpublished-- rights reserved under the copyright laws of the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
  51 trackball(float q[4], float p1x, float p1y, float p2x, float p2y);
  52
  53 /*
  54  * Given two quaternions, add them together to get a third quaternion.
  55  * Adding quaternions to get a compound rotation is analagous to adding
  56  * translations to get a compound translation.  When incrementally
  57  * adding rotations, the first argument here should be the new
  58  * rotation, the second and third the total rotation (which will be
  59  * over-written with the resulting new total rotation).
  60  */
  61 void
  62 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
  69 build_rotmatrix(float m[4][4], float q[4]);
  70
  71 /*
  72  * This function computes a quaternion based on an axis (defined by
  73  * the given vector) and an angle about which to rotate.  The angle is
  74  * expressed in radians.  The result is put into the third argument.
  75  */
  76 void
  77 axis_to_quat(float a[3], float phi, float q[4]);
  78