def test_hit_when_all_intersections_have_negative_t(self):
s = Sphere()
i1 = Intersection(-2, s)
i2 = Intersection(-1, s)
xs = intersections(i1, i2)
h = hit(xs)
self.assertIsNone(h)
def test_hit_when_some_intersections_have_negative_t(self):
s = Sphere()
i1 = Intersection(-1, s)
i2 = Intersection(1, s)
xs = intersections(i1, i2)
h = hit(xs)
self.assertEqual(i2, h)
def test_hit_when_all_intersections_have_positive_t(self):
s = Sphere()
i1 = Intersection(1, s)
i2 = Intersection(2, s)
xs = intersections(i1, i2)
h = hit(xs)
self.assertEqual(i1, h)
def test_aggregating_intersections(self):
s = sphere.Sphere()
i1 = Intersection(1, s)
i2 = Intersection(2, s)
xs = intersections(i1, i2)
self.assertEqual(2, len(xs))
self.assertEqual(1, xs[0].t)
self.assertEqual(2, xs[1].t)
def color_at(world, ray):
xss = intersect_world(world, ray)
xs = intersections(xss)
for item in xs:
h = hit(item)
if h is None:
return black
else:
h.prepare_hit(ray)
return shade_hit(world, h)
def test_hit_is_always__lowest_negative_intersection(self):
s = Sphere()
i1 = Intersection(5, s)
i2 = Intersection(7, s)
i3 = Intersection(-3, s)
i4 = Intersection(2, s)
xs = intersections(i1, i2, i3, i4)
h = hit(xs)
self.assertEqual(i4, h)