1 files changed, 154 insertions, 0 deletions
diff --git a/libdimension/model/objects/cube.c b/libdimension/model/objects/cube.c
new file mode 100644
index 0000000..7d6fe0f
--- /dev/null
+++ b/libdimension/model/objects/cube.c
@@ -0,0 +1,154 @@
+/*************************************************************************
+ * Copyright (C) 2009-2014 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
+ * Cubes.
+ */
+
+#include "dimension/model.h"
+#include <math.h>
+
+/// Intersection callback for a cube.
+static bool
+dmnsn_cube_intersection_fn(const dmnsn_object *cube, dmnsn_ray ray,
+                           dmnsn_intersection *intersection)
+{
+  // Clip the given ray against the X, Y, and Z slabs
+
+  dmnsn_vector nmin, nmax;
+  double tmin, tmax;
+
+  double tx1 = (-1.0 - ray.x0.x)/ray.n.x;
+  double tx2 = (+1.0 - ray.x0.x)/ray.n.x;
+
+  if (tx1 < tx2) {
+    tmin = tx1;
+    tmax = tx2;
+    nmin = dmnsn_new_vector(-1.0, 0.0, 0.0);
+    nmax = dmnsn_new_vector(+1.0, 0.0, 0.0);
+  } else {
+    tmin = tx2;
+    tmax = tx1;
+    nmin = dmnsn_new_vector(+1.0, 0.0, 0.0);
+    nmax = dmnsn_new_vector(-1.0, 0.0, 0.0);
+  }
+
+  if (tmin > tmax)
+    return false;
+
+  double ty1 = (-1.0 - ray.x0.y)/ray.n.y;
+  double ty2 = (+1.0 - ray.x0.y)/ray.n.y;
+
+  if (ty1 < ty2) {
+    if (ty1 > tmin) {
+      tmin = ty1;
+      nmin = dmnsn_new_vector(0.0, -1.0, 0.0);
+    }
+    if (ty2 < tmax) {
+      tmax = ty2;
+      nmax = dmnsn_new_vector(0.0, +1.0, 0.0);
+    }
+  } else {
+    if (ty2 > tmin) {
+      tmin = ty2;
+      nmin = dmnsn_new_vector(0.0, +1.0, 0.0);
+    }
+    if (ty1 < tmax) {
+      tmax = ty1;
+      nmax = dmnsn_new_vector(0.0, -1.0, 0.0);
+    }
+  }
+
+  if (tmin > tmax)
+    return false;
+
+  double tz1 = (-1.0 - ray.x0.z)/ray.n.z;
+  double tz2 = (+1.0 - ray.x0.z)/ray.n.z;
+
+  if (tz1 < tz2) {
+    if (tz1 > tmin) {
+      tmin = tz1;
+      nmin = dmnsn_new_vector(0.0, 0.0, -1.0);
+    }
+    if (tz2 < tmax) {
+      tmax = tz2;
+      nmax = dmnsn_new_vector(0.0, 0.0, +1.0);
+    }
+  } else {
+    if (tz2 > tmin) {
+      tmin = tz2;
+      nmin = dmnsn_new_vector(0.0, 0.0, +1.0);
+    }
+    if (tz1 < tmax) {
+      tmax = tz1;
+      nmax = dmnsn_new_vector(0.0, 0.0, -1.0);
+    }
+  }
+
+  if (tmin > tmax)
+    return false;
+
+  if (tmin < 0.0) {
+    tmin = tmax;
+    nmin = nmax;
+  }
+
+  if (tmin >= 0.0) {
+    intersection->t      = tmin;
+    intersection->normal = nmin;
+    return true;
+  } else {
+    return false;
+  }
+}
+
+/// Inside callback for a cube.
+static bool
+dmnsn_cube_inside_fn(const dmnsn_object *cube, dmnsn_vector point)
+{
+  return point.x > -1.0 && point.x < 1.0
+      && point.y > -1.0 && point.y < 1.0
+      && point.z > -1.0 && point.z < 1.0;
+}
+
+/// Boundary callback for a cube.
+static dmnsn_aabb
+dmnsn_cube_bounding_fn(const dmnsn_object *object, dmnsn_matrix trans)
+{
+  dmnsn_aabb box = dmnsn_symmetric_aabb(dmnsn_new_vector(1.0, 1.0, 1.0));
+  return dmnsn_transform_aabb(trans, box);
+}
+
+/// Cube vtable.
+static const dmnsn_object_vtable dmnsn_cube_vtable = {
+  .intersection_fn = dmnsn_cube_intersection_fn,
+  .inside_fn = dmnsn_cube_inside_fn,
+  .bounding_fn = dmnsn_cube_bounding_fn,
+};
+
+// Allocate a new cube object
+dmnsn_object *
+dmnsn_new_cube(dmnsn_pool *pool)
+{
+  dmnsn_object *cube = dmnsn_new_object(pool);
+  cube->vtable = &dmnsn_cube_vtable;
+  return cube;
+}