diff --git a/src/bound.rs b/src/bound.rs
new file mode 100644
index 0000000..33a20b9
--- /dev/null
+++ b/src/bound.rs
@@ -0,0 +1,60 @@
+// Copyright 2013-2014 The CGMath Developers. For a full listing of the authors,
+// refer to the AUTHORS file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Generic spatial bounds.
+
+use aabb::{Aabb, Aabb3};
+use num::BaseNum;
+use plane::Plane;
+use point::{Point, Point3};
+
+/// Spatial relation between two objects.
+pub enum Relation {
+	/// Completely inside
+	In,
+	/// Crosses the boundary
+	Cross,
+	/// Completely outside
+	Out,
+}
+
+/// Generic bound.
+pub trait Bound<S> {
+	/// Classify the spatial relation with a plane
+	fn relate(&self, &Plane<S>) -> Relation;
+}
+
+impl<S: BaseNum> Bound<S> for Point3<S> {
+	fn relate(&self, plane: &Plane<S>) -> Relation {
+		let dist = self.dot(&plane.n);
+		if dist > plane.d {
+			Relation::In
+		}else if dist < plane.d {
+			Relation::Out
+		}else {
+			Relation::Cross
+		}
+	}
+}
+
+impl<S: BaseNum> Bound<S> for Aabb3<S> {
+	fn relate(&self, plane: &Plane<S>) -> Relation {
+		match (self.min.relate(plane), self.max.relate(plane)) {
+			(Relation::In, Relation::In) => Relation::In,
+			(Relation::Out, Relation::Out) => Relation::Out,
+			(_, _) => Relation::Cross,
+		}
+	}
+}
diff --git a/src/cgmath.rs b/src/cgmath.rs
index c8335da..c0c7df8 100644
--- a/src/cgmath.rs
+++ b/src/cgmath.rs
@@ -16,6 +16,7 @@
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![feature(old_impl_check, plugin, core, std_misc, custom_derive)]
+#![plugin(rand_macros)]
 
 //! Computer graphics-centric math.
 //!
@@ -52,6 +53,7 @@ pub use transform::*;
 pub use projection::*;
 
 pub use aabb::*;
+pub use bound::*;
 pub use cylinder::Cylinder;
 pub use frustum::{Frustum, FrustumPoints};
 pub use intersect::Intersect;
@@ -80,6 +82,7 @@ mod transform;
 mod projection;
 
 mod aabb;
+mod bound;
 mod cylinder;
 mod frustum;
 mod intersect;