From 9563ecb2efb2eec6d83fa4f73b75dfb4dccbc34c Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@gmail.com>
Date: Thu, 15 Apr 2010 15:16:07 -0400
Subject: Add plane object.

---
 libdimension/Makefile.am         |  1 +
 libdimension/dimension/objects.h |  3 ++
 libdimension/plane.c             | 83 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 87 insertions(+)
 create mode 100644 libdimension/plane.c

(limited to 'libdimension')

diff --git a/libdimension/Makefile.am b/libdimension/Makefile.am
index d32643a..7b3cee0 100644
--- a/libdimension/Makefile.am
+++ b/libdimension/Makefile.am
@@ -68,6 +68,7 @@ libdimension_la_SOURCES = $(nobase_include_HEADERS)                            \
                           object.c                                             \
                           perspective.c                                        \
                           phong.c                                              \
+                          plane.c                                              \
                           point_light.c                                        \
                           progress.c                                           \
                           raytrace.c                                           \
diff --git a/libdimension/dimension/objects.h b/libdimension/dimension/objects.h
index 3176439..6f3b797 100644
--- a/libdimension/dimension/objects.h
+++ b/libdimension/dimension/objects.h
@@ -25,6 +25,9 @@
 #ifndef DIMENSION_OBJECTS_H
 #define DIMENSION_OBJECTS_H
 
+/* A plane through the origin, with the given normal */
+dmnsn_object *dmnsn_new_plane(dmnsn_vector normal);
+
 /* A sphere object, of radius 1, centered at the origin. */
 dmnsn_object *dmnsn_new_sphere();
 
diff --git a/libdimension/plane.c b/libdimension/plane.c
new file mode 100644
index 0000000..e475c46
--- /dev/null
+++ b/libdimension/plane.c
@@ -0,0 +1,83 @@
+/*************************************************************************
+ * 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"
+#include <math.h>
+
+/*
+ * Plane
+ */
+
+/* Plane object callbacks */
+
+static bool dmnsn_plane_intersection_fn(const dmnsn_object *plane,
+                                         dmnsn_line line,
+                                         dmnsn_intersection *intersection);
+static bool dmnsn_plane_inside_fn(const dmnsn_object *plane,
+                                   dmnsn_vector point);
+
+/* Allocate a new plane */
+dmnsn_object *
+dmnsn_new_plane(dmnsn_vector normal)
+{
+  dmnsn_object *plane = dmnsn_new_object();
+
+  dmnsn_vector *param = dmnsn_malloc(sizeof(dmnsn_vector));
+  *param = normal;
+
+  plane->intersection_fn  = &dmnsn_plane_intersection_fn;
+  plane->inside_fn        = &dmnsn_plane_inside_fn;
+  plane->free_fn          = &free;
+  plane->bounding_box.min = dmnsn_new_vector(-INFINITY, -INFINITY, -INFINITY);
+  plane->bounding_box.max = dmnsn_new_vector(INFINITY, INFINITY, INFINITY);
+  plane->ptr              = param;
+  return plane;
+}
+
+/* Returns the closest intersection of `line' with `plane' */
+static bool
+dmnsn_plane_intersection_fn(const dmnsn_object *plane, dmnsn_line line,
+                            dmnsn_intersection *intersection)
+{
+  dmnsn_vector *normal = plane->ptr;
+
+  dmnsn_line line_trans = dmnsn_matrix_line_mul(plane->trans_inv, line);
+  double den = dmnsn_vector_dot(line_trans.n, *normal);
+  if (den != 0.0) {
+    double t = -dmnsn_vector_dot(line_trans.x0, *normal)/den;
+    if (t >= 0.0) {
+      intersection->ray      = line;
+      intersection->t        = t;
+      intersection->normal   = dmnsn_matrix_normal_mul(plane->trans, *normal);
+      intersection->texture  = plane->texture;
+      intersection->interior = plane->interior;
+      return true;
+    }
+  }
+  return false;
+}
+
+/* Return whether a point is inside a plane (x**2 + y**2 + z**2 < 1.0) */
+static bool
+dmnsn_plane_inside_fn(const dmnsn_object *plane, dmnsn_vector point)
+{
+  dmnsn_vector *normal = plane->ptr;
+  return dmnsn_vector_dot(point, *normal) < 0.0;
+}
-- 
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