1 /*

2 libvmath - a vector math library

3 Copyright (C) 2004-2011 John Tsiombikas <nuclear@member.fsf.org>

4

5 This program is free software: you can redistribute it and/or modify

6 it under the terms of the GNU Lesser General Public License as published

7 by the Free Software Foundation, either version 3 of the License, or

8 (at your option) any later version.

9

10 This program is distributed in the hope that it will be useful,

11 but WITHOUT ANY WARRANTY; without even the implied warranty of

12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

13 GNU Lesser General Public License for more details.

14

15 You should have received a copy of the GNU Lesser General Public License

16 along with this program. If not, see <http://www.gnu.org/licenses/>.

17 */

18

19

20 #include <stdio.h>

21 #include <math.h>

22 #include "quat.h"

23

24 void quat_print(FILE *fp, quat_t q)

25 {

26 fprintf(fp, "([ %.4f %.4f %.4f ] %.4f)", q.x, q.y, q.z, q.w);

27 }

28

29 quat_t quat_rotate(quat_t q, scalar_t angle, scalar_t x, scalar_t y, scalar_t z)

30 {

31 quat_t rq;

32 scalar_t half_angle = angle * 0.5;

33 scalar_t sin_half = sin(half_angle);

34

35 rq.w = cos(half_angle);

36 rq.x = x * sin_half;

37 rq.y = y * sin_half;

38 rq.z = z * sin_half;

39

40 return quat_mul(q, rq);

41 }

42

43 quat_t quat_rotate_quat(quat_t q, quat_t rotq)

44 {

45 return quat_mul(quat_mul(rotq, q), quat_conjugate(rotq));

46 }

47

48 quat_t quat_slerp(quat_t q1, quat_t q2, scalar_t t)

49 {

50 quat_t res;

51 scalar_t angle = acos(q1.w * q2.w + q1.x * q2.x + q1.y * q2.y + q1.z * q2.z);

52 scalar_t a = sin((1.0f - t) * angle);

53 scalar_t b = sin(t * angle);

54 scalar_t c = sin(angle);

55

56 res.x = (q1.x * a + q2.x * b) / c;

57 res.y = (q1.y * a + q2.y * b) / c;

58 res.z = (q1.z * a + q2.z * b) / c;

59 res.w = (q1.w * a + q2.w * b) / c;

60 return quat_normalize(res);

61 }