nuclear@2: /*
nuclear@2: libvmath - a vector math library
nuclear@2: Copyright (C) 2004-2011 John Tsiombikas <nuclear@member.fsf.org>
nuclear@2: 
nuclear@2: This program is free software: you can redistribute it and/or modify
nuclear@2: it under the terms of the GNU Lesser General Public License as published
nuclear@2: by the Free Software Foundation, either version 3 of the License, or
nuclear@2: (at your option) any later version.
nuclear@2: 
nuclear@2: This program is distributed in the hope that it will be useful,
nuclear@2: but WITHOUT ANY WARRANTY; without even the implied warranty of
nuclear@2: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
nuclear@2: GNU Lesser General Public License for more details.
nuclear@2: 
nuclear@2: You should have received a copy of the GNU Lesser General Public License
nuclear@2: along with this program.  If not, see <http://www.gnu.org/licenses/>.
nuclear@2: */
nuclear@2: 
nuclear@2: 
nuclear@2: #include <stdio.h>
nuclear@2: #include <math.h>
nuclear@2: #include "quat.h"
nuclear@2: 
nuclear@2: void quat_print(FILE *fp, quat_t q)
nuclear@2: {
nuclear@2: 	fprintf(fp, "([ %.4f %.4f %.4f ] %.4f)", q.x, q.y, q.z, q.w);
nuclear@2: }
nuclear@2: 
nuclear@2: quat_t quat_rotate(quat_t q, scalar_t angle, scalar_t x, scalar_t y, scalar_t z)
nuclear@2: {
nuclear@2: 	quat_t rq;
nuclear@2: 	scalar_t half_angle = angle * 0.5;
nuclear@2: 	scalar_t sin_half = sin(half_angle);
nuclear@2: 
nuclear@2: 	rq.w = cos(half_angle);
nuclear@2: 	rq.x = x * sin_half;
nuclear@2: 	rq.y = y * sin_half;
nuclear@2: 	rq.z = z * sin_half;
nuclear@2: 
nuclear@2: 	return quat_mul(q, rq);
nuclear@2: }
nuclear@2: 
nuclear@2: quat_t quat_rotate_quat(quat_t q, quat_t rotq)
nuclear@2: {
nuclear@2: 	return quat_mul(quat_mul(rotq, q), quat_conjugate(rotq));
nuclear@2: }
nuclear@2: 
nuclear@2: quat_t quat_slerp(quat_t q1, quat_t q2, scalar_t t)
nuclear@2: {
nuclear@2: 	quat_t res;
nuclear@2: 	scalar_t angle = acos(q1.w * q2.w + q1.x * q2.x + q1.y * q2.y + q1.z * q2.z);
nuclear@2: 	scalar_t a = sin((1.0f - t) * angle);
nuclear@2: 	scalar_t b = sin(t * angle);
nuclear@2: 	scalar_t c = sin(angle);
nuclear@2: 
nuclear@2: 	res.x = (q1.x * a + q2.x * b) / c;
nuclear@2: 	res.y = (q1.y * a + q2.y * b) / c;
nuclear@2: 	res.z = (q1.z * a + q2.z * b) / c;
nuclear@2: 	res.w = (q1.w * a + q2.w * b) / c;
nuclear@2: 	return quat_normalize(res);
nuclear@2: }