1 files changed, 58 insertions, 0 deletions
diff --git a/libdimension/lambertian.c b/libdimension/lambertian.c
new file mode 100644
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--- /dev/null
+++ b/libdimension/lambertian.c
@@ -0,0 +1,58 @@
+/*************************************************************************
+ * 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_lambertian_diffuse_fn(const dmnsn_diffuse *diffuse,
+                            dmnsn_color light, dmnsn_color color,
+                            dmnsn_vector ray, dmnsn_vector normal)
+{
+  double *coeff = diffuse->ptr;
+  double diffuse_factor = fabs((*coeff)*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_diffuse *
+dmnsn_new_lambertian(double diffuse)
+{
+  dmnsn_diffuse *lambertian = dmnsn_new_diffuse();
+
+  double *param = dmnsn_malloc(sizeof(double));
+  *param = diffuse;
+
+  lambertian->diffuse_fn = dmnsn_lambertian_diffuse_fn;
+  lambertian->free_fn    = dmnsn_free;
+  lambertian->ptr        = param;
+
+  return lambertian;
+}