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+/*************************************************************************
+ * Copyright (C) 2009 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 <stdlib.h> /* For malloc */
+#include <math.h>
+
+/*
+ * Phong finish
+ */
+
+static dmnsn_color
+dmnsn_phong_finish_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 = pow(dmnsn_vector_dot(reflected, viewer), 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);
+ return NULL;
+ }
+
+ params[0] = specular;
+ params[1] = exp;
+
+ finish->ptr = params;
+ finish->finish_fn = &dmnsn_phong_finish_fn;
+ finish->free_fn = &free;
+ }
+ return finish;
+}