1 files changed, 69 insertions, 0 deletions
diff --git a/libdimension/model/finishes/phong.c b/libdimension/model/finishes/phong.c
new file mode 100644
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+++ b/libdimension/model/finishes/phong.c
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+/*************************************************************************
+ * Copyright (C) 2010-2014 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
+ * Phong highlights.
+ */
+
+#include "dimension/model.h"
+#include <stdlib.h>
+
+/// Phone specular type.
+typedef struct dmnsn_phong {
+  dmnsn_specular specular;
+  double coeff;
+  double exp;
+} dmnsn_phong;
+
+/// Phong specular highlight callback.
+static dmnsn_color
+dmnsn_phong_specular_fn(const dmnsn_specular *specular,
+                        dmnsn_color light, dmnsn_color color,
+                        dmnsn_vector ray, dmnsn_vector normal,
+                        dmnsn_vector viewer)
+{
+  const dmnsn_phong *phong = (const dmnsn_phong *)specular;
+
+  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, phong->exp);
+  return dmnsn_color_mul(phong->coeff*specular_factor, light);
+}
+
+// A phong finish
+dmnsn_specular *
+dmnsn_new_phong(dmnsn_pool *pool, double coeff, double exp)
+{
+  dmnsn_phong *phong = DMNSN_PALLOC(pool, dmnsn_phong);
+  phong->coeff = coeff;
+  phong->exp = exp;
+
+  dmnsn_specular *specular = &phong->specular;
+  dmnsn_init_specular(specular);
+  specular->specular_fn = dmnsn_phong_specular_fn;
+  return specular;
+}