diff --git a/engine/libraries/coll2d/include/coll2d.h b/engine/libraries/coll2d/include/coll2d.h
index 2693a40..351de72 100644
--- a/engine/libraries/coll2d/include/coll2d.h
+++ b/engine/libraries/coll2d/include/coll2d.h
@@ -76,6 +76,7 @@ protected:
 	vector3d mVelocity;
 	float mAngle;
 	float mAngleVelocity;
+	float mBoundingRadius;
 
 	virtual void dummy() {
 	}
@@ -84,13 +85,15 @@ public:
 		mPosition (0., 0., 0.),
 		mVelocity (0., 0., 0.),
 		mAngle (0.),
-		mAngleVelocity (0.) {
+		mAngleVelocity (0.),
+		mBoundingRadius (0.) {
 	}
 	Shape (const Shape &shape):
 		mPosition (shape.mPosition),
 		mVelocity (shape.mVelocity),
 		mAngle (shape.mAngle),
-		mAngleVelocity (shape.mAngleVelocity)
+		mAngleVelocity (shape.mAngleVelocity),
+		mBoundingRadius (shape.mBoundingRadius)
 	{ }
 
 	virtual ~Shape () {};
@@ -123,6 +126,12 @@ public:
 	float getAngleVelocity () {
 		return mAngleVelocity;
 	}
+	void setBoundingRadius (float bounding_radius) {
+		mBoundingRadius = bounding_radius;
+	}
+	float getBoundingRadius () {
+		return mBoundingRadius;
+	}
 
 	virtual void doPrintType() {
 		std::cout << "Shape" << std::endl;
@@ -160,6 +169,7 @@ public:
 		}
 
 		mVertices = vertices;
+		updateBoundingRadius();
 	}
 	Polygon (const Polygon &polygon) : Shape (polygon) {
 		mVerticeCount = polygon.mVerticeCount;
@@ -167,6 +177,8 @@ public:
 
 		mVertices = new vector3d[mVerticeCount];
 		memcpy (mVertices, polygon.mVertices, sizeof (vector3d) * mVerticeCount);
+
+		mBoundingRadius = polygon.mBoundingRadius;
 	}
 	virtual ~Polygon () {
 		if (mFreeVertices == true && mVertices)
@@ -205,6 +217,7 @@ public:
 
 		std::cout << "mAngle = " << mAngle << std::endl;
 		std::cout << "mAngleVelocity = " << mAngleVelocity << std::endl;
+		std::cout << "mBoundingRadius = " << mBoundingRadius << std::endl;
 	}
 
 	unsigned int getVerticeCount () {
@@ -219,6 +232,20 @@ public:
 	void setVertice (unsigned int i, const vector3d &vertice) {
 		assert (i >= 0 && i < mVerticeCount);
 		mVertices[i] = vertice;
+
+		updateBoundingRadius();
+	}
+
+	void updateBoundingRadius () {
+		unsigned int i;
+		float max_vertice_dist2 = 0.;
+		for (i = 0; i < mVerticeCount; i++) {
+			float vertice_dist2 = mVertices[i].length2();
+			if (vertice_dist2 > max_vertice_dist2)
+				max_vertice_dist2 = vertice_dist2;
+		}
+
+		mBoundingRadius = sqrt (max_vertice_dist2);
 	}
 
 	friend int check_collision_polygon_sphere(Shape *polygon_a,
@@ -231,17 +258,20 @@ private:
 public:
 	Sphere (float radius) {
 		mRadius = radius;
+		mBoundingRadius = radius;
 		Shape::setPosition (vector3d (0., 0., 0.));
 	}
 
 	Sphere(float radius, const vector3d &position) {
 		mRadius = radius;
+		mBoundingRadius = radius;
 		Shape::setPosition(position);
 	}
 
 	Sphere (const Sphere &sphere):
 		Shape (sphere),
-		mRadius (sphere.mRadius) { }
+		mRadius (sphere.mRadius)
+		{ mBoundingRadius = mRadius; }
 
 	virtual Sphere* getCopy() {
 		Sphere* copy = new Sphere (*this);
@@ -269,7 +299,6 @@ public:
 		std::cout << "mAngleVelocity = " << mAngleVelocity << std::endl;
 	}
 
-
 	void setRadius (float radius) {
 		mRadius = radius;
 	}
diff --git a/engine/libraries/coll2d/tests/general.cc b/engine/libraries/coll2d/tests/general.cc
index f68289a..ad9276c 100644
--- a/engine/libraries/coll2d/tests/general.cc
+++ b/engine/libraries/coll2d/tests/general.cc
@@ -23,6 +23,9 @@ TEST ( SphereCopyConstructer ) {
 	velocity_b = sphere_b.getVelocity ();
 
 	CHECK (velocity_a != velocity_b );
+
+	CHECK_EQUAL (123., sphere_a.getBoundingRadius());
+	CHECK_EQUAL (123., sphere_b.getBoundingRadius());
 }
 
 TEST ( PolygonCopyConstructer ) {
@@ -47,6 +50,8 @@ TEST ( PolygonCopyConstructer ) {
 	CHECK (vertice1 == polygon_b.getVertice (1));
 	CHECK (vertice2 == polygon_b.getVertice (2));
 
+	CHECK_CLOSE (sqrt (2.), polygon_a.getBoundingRadius(), 1.0e-7);
+
 	polygon_b.setVelocity (vector3d (0., 0., 0.));
 	velocity_a = polygon_a.getVelocity ();
 	velocity_b = polygon_b.getVelocity ();
@@ -280,5 +285,3 @@ TEST ( SphereSetGetRadius ) {
 	sphere.setRadius (456.);
 	CHECK_EQUAL (456, sphere.getRadius());
 }
-
-