Implement reflection.

1 files changed, 74 insertions, 0 deletions

diff --git a/libdimension/reflective.c b/libdimension/reflective.c
new file mode 100644
index 0000000..f1c7355
--- /dev/null
+++ b/libdimension/reflective.c
@@ -0,0 +1,74 @@
+/*************************************************************************
+ * 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>
+
+/*
+ * Reflective finish
+ */
+
+typedef struct dmnsn_reflection_params {
+  dmnsn_color min, max;
+  double falloff;
+} dmnsn_reflection_params;
+
+static dmnsn_color
+dmnsn_reflective_finish_fn(const dmnsn_finish *finish,
+                           dmnsn_color reflect, dmnsn_color color,
+                           dmnsn_vector ray, dmnsn_vector normal)
+{
+  dmnsn_reflection_params *params = finish->ptr;
+  double reflection = pow(dmnsn_vector_dot(ray, normal), params->falloff);
+
+  return dmnsn_color_illuminate(
+    dmnsn_color_add(
+      dmnsn_color_mul(
+        reflection,
+        dmnsn_color_sub(params->max, params->min)
+      ),
+      params->min
+    ),
+    reflect
+  );
+}
+
+dmnsn_finish *
+dmnsn_new_reflective_finish(dmnsn_color min, dmnsn_color max, double falloff)
+{
+  dmnsn_finish *finish = dmnsn_new_finish();
+  if (finish) {
+    dmnsn_reflection_params *params = malloc(sizeof(dmnsn_reflection_params));
+    if (!params) {
+      dmnsn_delete_finish(finish);
+      return NULL;
+    }
+
+    params->min     = min;
+    params->max     = max;
+    params->falloff = falloff;
+
+    finish->ptr           = params;
+    finish->reflection_fn = &dmnsn_reflective_finish_fn;
+    finish->free_fn       = &free;
+  }
+  return finish;
+}