nuclear@27: /*
nuclear@27: libvmath - a vector math library
nuclear@27: Copyright (C) 2004-2011 John Tsiombikas <nuclear@member.fsf.org>
nuclear@27: 
nuclear@27: This program is free software: you can redistribute it and/or modify
nuclear@27: it under the terms of the GNU Lesser General Public License as published
nuclear@27: by the Free Software Foundation, either version 3 of the License, or
nuclear@27: (at your option) any later version.
nuclear@27: 
nuclear@27: This program is distributed in the hope that it will be useful,
nuclear@27: but WITHOUT ANY WARRANTY; without even the implied warranty of
nuclear@27: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
nuclear@27: GNU Lesser General Public License for more details.
nuclear@27: 
nuclear@27: You should have received a copy of the GNU Lesser General Public License
nuclear@27: along with this program.  If not, see <http://www.gnu.org/licenses/>.
nuclear@27: */
nuclear@27: 
nuclear@27: #include <stdlib.h>
nuclear@27: 
nuclear@27: static inline scalar_t smoothstep(float a, float b, float x)
nuclear@27: {
nuclear@27: 	if(x < a) return 0.0;
nuclear@27: 	if(x >= b) return 1.0;
nuclear@27: 
nuclear@27: 	x = (x - a) / (b - a);
nuclear@27: 	return x * x * (3.0 - 2.0 * x);
nuclear@27: }
nuclear@27: 
nuclear@27: /** Generates a random number in [0, range) */
nuclear@27: static inline scalar_t frand(scalar_t range)
nuclear@27: {
nuclear@27: 	return range * (scalar_t)rand() / (scalar_t)RAND_MAX;
nuclear@27: }
nuclear@27: 
nuclear@27: /** Generates a random vector on the surface of a sphere */
nuclear@27: static inline vec3_t sphrand(scalar_t rad)
nuclear@27: {
nuclear@27: 	scalar_t u = (scalar_t)rand() / RAND_MAX;
nuclear@27: 	scalar_t v = (scalar_t)rand() / RAND_MAX;
nuclear@27: 
nuclear@27: 	scalar_t theta = 2.0 * M_PI * u;
nuclear@27: 	scalar_t phi = acos(2.0 * v - 1.0);
nuclear@27: 
nuclear@27: 	vec3_t res;
nuclear@27: 	res.x = rad * cos(theta) * sin(phi);
nuclear@27: 	res.y = rad * sin(theta) * sin(phi);
nuclear@27: 	res.z = rad * cos(phi);
nuclear@27: 	return res;
nuclear@27: }
nuclear@27: 
nuclear@27: /** linear interpolation */
nuclear@27: static inline scalar_t lerp(scalar_t a, scalar_t b, scalar_t t)
nuclear@27: {
nuclear@27: 	return a + (b - a) * t;
nuclear@27: }