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/*************************************************************************
 * Copyright (C) 2010 Tavian Barnes <tavianator@tavianator.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/>.                                       *
 *************************************************************************/

/**
 * @file
 * Diffuse finish.
 */

#include "dimension.h"
#include <math.h>
#include <stdlib.h>

/** Diffuse finish callback. */
static dmnsn_color
dmnsn_diffuse_finish_fn(const dmnsn_finish *finish,
                        dmnsn_color light, dmnsn_color color,
                        dmnsn_vector ray, dmnsn_vector normal)
{
  double *diffuse = finish->ptr;
  double diffuse_factor = fabs((*diffuse)*dmnsn_vector_dot(ray, normal));
  dmnsn_color ret
    = dmnsn_color_mul(diffuse_factor, dmnsn_color_illuminate(light, color));
  ret.filter = 0.0;
  ret.trans  = 0.0;
  return ret;
}

dmnsn_finish *
dmnsn_new_diffuse_finish(double diffuse)
{
  dmnsn_finish *finish = dmnsn_new_finish();

  double *param = dmnsn_malloc(sizeof(double));
  *param = diffuse;

  finish->ptr        = param;
  finish->diffuse_fn = &dmnsn_diffuse_finish_fn;
  finish->free_fn    = &dmnsn_free;

  return finish;
}