def test_force_rational(self):
# more or less random 3D surface with p=[3,2] and n=[4,3]
controlpoints = [[0, 0, 1], [-1, 1, 1], [0, 2, 1], [1, -1, 1],
[1, 0, 1], [1, 1, 1], [2, 1, 1], [2, 2, 1], [2, 3, 1],
[3, 0, 1], [4, 1, 1], [3, 2, 1]]
basis1 = BSplineBasis(4, [0, 0, 0, 0, 2, 2, 2, 2])
basis2 = BSplineBasis(3, [0, 0, 0, 1, 1, 1])
surf = Surface(basis1, basis2, controlpoints)
evaluation_point1 = surf(0.23, .66)
control_point1 = surf[0]
surf.force_rational()
evaluation_point2 = surf(0.23, .66)
control_point2 = surf[0]
# ensure that surface has not chcanged, by comparing evaluation of it
self.assertAlmostEqual(evaluation_point1[0], evaluation_point2[0])
self.assertAlmostEqual(evaluation_point1[1], evaluation_point2[1])
self.assertAlmostEqual(evaluation_point1[2], evaluation_point2[2])
# ensure that we include rational weights of 1
self.assertEqual(len(control_point1), 3)
self.assertEqual(len(control_point2), 4)
self.assertEqual(control_point2[3], 1)
self.assertEqual(surf.rational, True)
