Axis-aligned boxes use top and bottom corners

Fixes issue #35.

src/cgmath/aabb.rs

@@ -16,16 +16,37 @@
 //! Axis-aligned bounding boxes
 
 use point::{Point2, Point3};
-use vector::{Vec2, Vec3};
 
 #[deriving(Clone, Eq)]
 pub struct Aabb2<S> {
-    center: Point2<S>,
-    size: Vec2<S>,
+    min: Point2<S>,
+    max: Point2<S>,
+}
+
+impl<S: Num + Orderable> Aabb2<S> {
+    /// Construct a new axis-aligned bounding box from two points.
+    #[inline]
+    pub fn new(p1: &Point2<S>, p2: &Point2<S>) -> Aabb2<S> {
+        Aabb2 {
+            min: Point2::new(p1.x.min(&p2.x), p1.y.min(&p2.y)),
+            max: Point2::new(p1.x.max(&p2.x), p1.y.max(&p2.y)),
+        }
+    }
 }
 
 #[deriving(Clone, Eq)]
 pub struct Aabb3<S> {
-    center: Point3<S>,
-    size: Vec3<S>,
+    min: Point3<S>,
+    max: Point3<S>,
+}
+
+impl<S: Num + Orderable> Aabb3<S> {
+    /// Construct a new axis-aligned bounding box from two points.
+    #[inline]
+    pub fn new(p1: &Point3<S>, p2: &Point3<S>) -> Aabb3<S> {
+        Aabb3 {
+            min: Point3::new(p1.x.min(&p2.x), p1.y.min(&p2.y), p1.z.min(&p2.z)),
+            max: Point3::new(p1.x.max(&p2.x), p1.y.max(&p2.y), p1.z.max(&p2.z)),
+        }
+    }
 }

src/test/aabb.rs

@@ -0,0 +1,13 @@
+use cgmath::aabb::{Aabb2, Aabb3};
+use cgmath::point::{Point2, Point3};
+
+#[test]
+fn test_aabb() {
+    let aabb = Aabb2::new(&Point2::new(-20f64, 30f64), &Point2::new(10f64, -10f64));
+    assert_eq!(aabb.min, Point2::new(-20f64, -10f64));
+    assert_eq!(aabb.max, Point2::new(10f64, 30f64));
+
+    let aabb = Aabb3::new(&Point3::new(-20f64, 30f64, 0f64), &Point3::new(10f64, -10f64, -5f64));
+    assert_eq!(aabb.min, Point3::new(-20f64, -10f64, -5f64));
+    assert_eq!(aabb.max, Point3::new(10f64, 30f64, 0f64));
+}

src/test/test.rs

@@ -32,7 +32,7 @@ pub mod transform;
 
 // pub mod projection;
 
-// pub mod aabb;
+pub mod aabb;
 // pub mod cylinder;
 // pub mod frustum;
 // pub mod intersect;