1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/libs/vmath/quat_c.c	Sun Nov 01 00:36:56 2015 +0200
     1.3 @@ -0,0 +1,89 @@
     1.4 +/*
     1.5 +libvmath - a vector math library
     1.6 +Copyright (C) 2004-2011 John Tsiombikas <nuclear@member.fsf.org>
     1.7 +
     1.8 +This program is free software: you can redistribute it and/or modify
     1.9 +it under the terms of the GNU Lesser General Public License as published
    1.10 +by the Free Software Foundation, either version 3 of the License, or
    1.11 +(at your option) any later version.
    1.12 +
    1.13 +This program is distributed in the hope that it will be useful,
    1.14 +but WITHOUT ANY WARRANTY; without even the implied warranty of
    1.15 +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    1.16 +GNU Lesser General Public License for more details.
    1.17 +
    1.18 +You should have received a copy of the GNU Lesser General Public License
    1.19 +along with this program.  If not, see <http://www.gnu.org/licenses/>.
    1.20 +*/
    1.21 +
    1.22 +
    1.23 +#include <stdio.h>
    1.24 +#include <math.h>
    1.25 +#include "quat.h"
    1.26 +
    1.27 +void quat_print(FILE *fp, quat_t q)
    1.28 +{
    1.29 +	fprintf(fp, "([ %.4f %.4f %.4f ] %.4f)", q.x, q.y, q.z, q.w);
    1.30 +}
    1.31 +
    1.32 +quat_t quat_rotate(quat_t q, scalar_t angle, scalar_t x, scalar_t y, scalar_t z)
    1.33 +{
    1.34 +	quat_t rq;
    1.35 +	scalar_t half_angle = angle * 0.5;
    1.36 +	scalar_t sin_half = sin(half_angle);
    1.37 +
    1.38 +	rq.w = cos(half_angle);
    1.39 +	rq.x = x * sin_half;
    1.40 +	rq.y = y * sin_half;
    1.41 +	rq.z = z * sin_half;
    1.42 +
    1.43 +	return quat_mul(q, rq);
    1.44 +}
    1.45 +
    1.46 +quat_t quat_rotate_quat(quat_t q, quat_t rotq)
    1.47 +{
    1.48 +	return quat_mul(quat_mul(rotq, q), quat_conjugate(rotq));
    1.49 +}
    1.50 +
    1.51 +quat_t quat_slerp(quat_t q1, quat_t q2, scalar_t t)
    1.52 +{
    1.53 +	quat_t res;
    1.54 +	scalar_t a, b, angle, sin_angle, dot;
    1.55 +
    1.56 +	dot = q1.w * q2.w + q1.x * q2.x + q1.y * q2.y + q1.z * q2.z;
    1.57 +	if(dot < 0.0) {
    1.58 +		/* make sure we interpolate across the shortest arc */
    1.59 +		q1.x = -q1.x;
    1.60 +		q1.y = -q1.y;
    1.61 +		q1.z = -q1.z;
    1.62 +		q1.w = -q1.w;
    1.63 +		dot = -dot;
    1.64 +	}
    1.65 +
    1.66 +	/* clamp dot to [-1, 1] in order to avoid domain errors in acos due to
    1.67 +	 * floating point imprecisions
    1.68 +	 */
    1.69 +	if(dot < -1.0) dot = -1.0;
    1.70 +	if(dot > 1.0) dot = 1.0;
    1.71 +
    1.72 +	angle = acos(dot);
    1.73 +	sin_angle = sin(angle);
    1.74 +
    1.75 +	if(fabs(sin_angle) < SMALL_NUMBER) {
    1.76 +		/* for very small angles or completely opposite orientations
    1.77 +		 * use linear interpolation to avoid div/zero (in the first case it makes sense,
    1.78 +		 * the second case is pretty much undefined anyway I guess ...
    1.79 +		 */
    1.80 +		a = 1.0f - t;
    1.81 +		b = t;
    1.82 +	} else {
    1.83 +		a = sin((1.0f - t) * angle) / sin_angle;
    1.84 +		b = sin(t * angle) / sin_angle;
    1.85 +	}
    1.86 +
    1.87 +	res.x = q1.x * a + q2.x * b;
    1.88 +	res.y = q1.y * a + q2.y * b;
    1.89 +	res.z = q1.z * a + q2.z * b;
    1.90 +	res.w = q1.w * a + q2.w * b;
    1.91 +	return res;
    1.92 +}