# tutorial: trackball.h

File trackball.h, 3.2 KB (added by , 6 years ago) |
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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31 | * Unpublished-- rights reserved under the copyright laws of the |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 | /* |

53 | * Given two quaternions, add them together to get a third quaternion. |

54 | * Adding quaternions to get a compound rotation is analagous to adding |

55 | * translations to get a compound translation. When incrementally |

56 | * adding rotations, the first argument here should be the new |

57 | * rotation, the second and third the total rotation (which will be |

58 | * over-written with the resulting new total rotation). |

59 | */ |

60 | void add_quats(float *q1, float *q2, float *dest); |

61 | |

62 | /* |

63 | * A useful function, builds a rotation matrix in Matrix based on |

64 | * given quaternion. |

65 | */ |

66 | void build_rotmatrix(float m[4][4], float q[4]); |

67 | |

68 | /* |

69 | * This function computes a quaternion based on an axis (defined by |

70 | * the given vector) and an angle about which to rotate. The angle is |

71 | * expressed in radians. The result is put into the third argument. |

72 | */ |

73 | void axis_to_quat(float a[3], float phi, float q[4]); |

74 | |

75 |