Add plane object.

1 files changed, 83 insertions, 0 deletions

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;
+}