From 5f11db695b74db219e0d06682728c9eda90cac5c Mon Sep 17 00:00:00 2001
From: Sven Strothoff <anonymous@invalid.net>
Date: Sun, 28 Jul 2013 23:59:37 +0200
Subject: [PATCH] bug #502: add bool intersects() methods to AlignedBox

---
 Eigen/src/Geometry/AlignedBox.h | 4 ++++
 test/geo_alignedbox.cpp         | 7 +++++++
 2 files changed, 11 insertions(+)

diff --git a/Eigen/src/Geometry/AlignedBox.h b/Eigen/src/Geometry/AlignedBox.h
index 8e186d57a..b6a2f0e24 100644
--- a/Eigen/src/Geometry/AlignedBox.h
+++ b/Eigen/src/Geometry/AlignedBox.h
@@ -185,6 +185,10 @@ EIGEN_MAKE_ALIGNED_OPERATOR_NEW_IF_VECTORIZABLE_FIXED_SIZE(_Scalar,_AmbientDim)
   inline bool contains(const AlignedBox& b) const
   { return (m_min.array()<=(b.min)().array()).all() && ((b.max)().array()<=m_max.array()).all(); }
 
+  /** \returns true if the box \a b is intersecting the box \c *this. */
+  inline bool intersects(const AlignedBox& b) const
+  { return (m_min.array()<=(b.max)().array()).all() && ((b.min)().array()<=m_max.array()).all(); }
+
   /** Extends \c *this such that it contains the point \a p and returns a reference to \c *this. */
   template<typename Derived>
   inline AlignedBox& extend(const MatrixBase<Derived>& a_p)
diff --git a/test/geo_alignedbox.cpp b/test/geo_alignedbox.cpp
index 8e36adbe3..e2792ed18 100644
--- a/test/geo_alignedbox.cpp
+++ b/test/geo_alignedbox.cpp
@@ -54,6 +54,13 @@ template<typename BoxType> void alignedbox(const BoxType& _box)
   VERIFY(b2.contains(b1));
   VERIFY_IS_APPROX(b2.clamp(b0), b0);
 
+  // intersection
+  BoxType box1(VectorType::Random(dim));
+  box1.extend(VectorType::Random(dim));
+  BoxType box2(VectorType::Random(dim));
+  box2.extend(VectorType::Random(dim));
+
+  VERIFY(box1.intersects(box2) == !box1.intersection(box2).isEmpty()); 
 
   // alignment -- make sure there is no memory alignment assertion
   BoxType *bp0 = new BoxType(dim);