 {
     var centre:Vector = Vector(x: 0.0, y: 0.0, z: 0.0)
     var radius:Double = 1.0
+    var radiusSquared:Double = 1.0
     
     /** 
         Currently using a geometric solver. 

    func intersectionPoint(ray:Ray) -> Vector?
    {
        if let t = intersection(ray) {
            return ray.atT(t)
        }
        return nil
    }

        return Vector()
    }
    
    func intersection (ray:Ray) -> Double?
    {
        return nil
