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/*************************************************************************
* Copyright (C) 2010 Tavian Barnes <tavianator@gmail.com> *
* *
* This file is part of The Dimension Library. *
* *
* The Dimension Library is free software; you can redistribute it and/ *
* or modify it under the terms of the GNU Lesser General Public License *
* as published by the Free Software Foundation; either version 3 of the *
* License, or (at your option) any later version. *
* *
* The Dimension Library is distributed in the hope that it will be *
* useful, but WITHOUT ANY WARRANTY; without even the implied warranty *
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
* Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public *
* License along with this program. If not, see *
* <http://www.gnu.org/licenses/>. *
*************************************************************************/
#include "dimension.h"
#include <errno.h>
#include <stdlib.h> /* For malloc */
#include <math.h>
/*
* Phong finish
*/
static dmnsn_color
dmnsn_phong_specular_fn(const dmnsn_finish *finish,
dmnsn_color light, dmnsn_color color,
dmnsn_vector ray, dmnsn_vector normal,
dmnsn_vector viewer)
{
double *params = finish->ptr;
double specular = params[0];
double exp = params[1];
dmnsn_vector proj = dmnsn_vector_mul(2*dmnsn_vector_dot(ray, normal), normal);
dmnsn_vector reflected = dmnsn_vector_sub(proj, ray);
double specular_factor = dmnsn_vector_dot(reflected, viewer);
if (specular_factor < 0.0) {
return dmnsn_black;
}
specular_factor = pow(specular_factor, exp);
return dmnsn_color_mul(specular*specular_factor, light);
}
/* A phong finish */
dmnsn_finish *
dmnsn_new_phong_finish(double specular, double exp)
{
dmnsn_finish *finish = dmnsn_new_finish();
if (finish) {
double *params = malloc(2*sizeof(double));
if (!params) {
dmnsn_delete_finish(finish);
errno = ENOMEM;
return NULL;
}
params[0] = specular;
params[1] = exp;
finish->ptr = params;
finish->specular_fn = &dmnsn_phong_specular_fn;
finish->free_fn = &free;
}
return finish;
}
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