Add gradient pattern.

3 files changed, 52 insertions, 0 deletions

diff --git a/libdimension/Makefile.am b/libdimension/Makefile.am
index 8558a48..7875682 100644
--- a/libdimension/Makefile.am
+++ b/libdimension/Makefile.am
@@ -66,6 +66,7 @@ libdimension_la_SOURCES = $(nobase_include_HEADERS)                            \
                           error.c                                              \
                           finish_combination.c                                 \
                           geometry.c                                           \
+                          gradient.c                                           \
                           inlines.c                                            \
                           interior.c                                           \
                           light.c                                              \
diff --git a/libdimension/dimension/patterns.h b/libdimension/dimension/patterns.h
index c6dc08a..cd4aa35 100644
--- a/libdimension/dimension/patterns.h
+++ b/libdimension/dimension/patterns.h
@@ -26,5 +26,6 @@
 #define DIMENSION_PATTERNS_H
 
 dmnsn_pattern *dmnsn_new_checker_pattern();
+dmnsn_pattern *dmnsn_new_gradient_pattern(dmnsn_vector orientation);
 
 #endif /* DIMENSION_PATTERNS_H */
diff --git a/libdimension/gradient.c b/libdimension/gradient.c
new file mode 100644
index 0000000..6bcb3b8
--- /dev/null
+++ b/libdimension/gradient.c
@@ -0,0 +1,50 @@
+/*************************************************************************
+ * Copyright (C) 2010 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"
+
+/*
+ * Gradient pattern
+ */
+
+static double
+dmnsn_gradient_pattern_fn(const dmnsn_pattern *gradient, dmnsn_vector v)
+{
+  dmnsn_vector *orientation = gradient->ptr;
+  double n = fmod(dmnsn_vector_dot(*orientation, v), 1.0);
+  if (n < -dmnsn_epsilon)
+    n += 1.0;
+  return n;
+}
+
+dmnsn_pattern *
+dmnsn_new_gradient_pattern(dmnsn_vector orientation)
+{
+  dmnsn_pattern *gradient = dmnsn_new_pattern();
+
+  dmnsn_vector *payload = dmnsn_malloc(sizeof(dmnsn_vector));
+  *payload = dmnsn_vector_normalize(orientation);
+
+  gradient->pattern_fn = &dmnsn_gradient_pattern_fn;
+  gradient->free_fn    = &dmnsn_free;
+  gradient->ptr        = payload;
+
+  return gradient;
+}