let hitSphere radius (texture:ITexture) =
    let innerHit o dir =
        match o, dir with
        | p, v ->
            let a = (pown (Vector.getX v) 2) + (pown (Vector.getY v) 2) + (pown (Vector.getZ v) 2)
            let b = 2.0*(Point.getX p * Vector.getX v + Point.getY p * Vector.getY v + Point.getZ p * Vector.getZ v )
            let c = (pown (Point.getX p) 2) + (pown (Point.getY p) 2) + (pown (Point.getZ p) 2) - (pown radius 2)
            let t1 = (-b + (sqrt((pown b 2) - 4.0 * a*c))) / (2.0 * a)
            let t2 = (-b - (sqrt((pown b 2) - 4.0 * a * c))) / (2.0 * a)

            let correctSolution = getCorrectPolySolution t1 t2

            if (correctSolution.IsSome) then
                let t = correctSolution.Value
                let hp = o + (t * dir)
                let v =  Vector.normalize (Vector.mkVector ((Point.getX hp) / radius) ((Point.getY hp) / radius) ((Point.getZ hp) / radius))
                let n =
                    if Vector.dotProduct v dir > 0.0 then
                            let x = - Vector.getX v
                            let y = - Vector.getY v
                            let z = - Vector.getZ v
                            Vector.mkVector x y z
                            else v


                 //Texture mapping
                let nx, ny, nz = Vector.getCoord n
                let theta = acos ny
                let phi' = atan2 nx nz
                let phi = if phi' < 0.0
                          then phi' + 2.0 * pi
                          else phi'

                let u = theta / (2.0 * pi)
                let v = (1.0 - phi) / pi
                let mat = texture.f u v

                Some (t, n, mat, hp)
            else None
    innerHit