def test_hit_all_intersections_negative_t(self):
s = Sphere()
i1 = Intersection(-2, s)
i2 = Intersection(-1, s)
xs = Intersection.intersections(i2, i1)
i = Intersection.hit(xs)
self.assertIsNone(i)
def test_hit_all_intersections_positive_t(self):
s = Sphere()
i1 = Intersection(1, s)
i2 = Intersection(2, s)
xs = Intersection.intersections(i2, i1)
i = Intersection.hit(xs)
self.assertEqual(i, i1)
def test_hit_some_intersections_negative_t(self):
s = Sphere()
i1 = Intersection(-1, s)
i2 = Intersection(1, s)
xs = Intersection.intersections(i2, i1)
i = Intersection.hit(xs)
self.assertEqual(i, i2)
def test_hit_lowest_nonnegative_intersection(self):
s = Sphere()
i1 = Intersection(5, s)
i2 = Intersection(7, s)
i3 = Intersection(-3, s)
i4 = Intersection(2, s)
xs = Intersection.intersections(i1, i2, i3, i4)
i = Intersection.hit(xs)
self.assertEqual(i, i4)
for x in range(canvas_pixels):
world_x = -half + pixel_size * x
position = Point(world_x, world_y, wall_z)
r = Ray(ray_origin, Vector.normalize(position - ray_origin))
# shrink along y-axis
# r = r.transform(Transformations.scaling(1, 0.5, 1))
# shrink along x-axis
# r = r.transform(Transformations.scaling(0.5, 1, 1))
# shrink and rotate
# r = r.transform(Transformations.rotation_z(math.pi / 4)).transform(Transformations.scaling(0.5, 1, 1))
# shrink and skew
# r = r.transform(Transformations.shearing(1, 0, 0, 0, 0, 0)).transform(Transformations.scaling(0.5, 1, 1))
xs = shape.intersect(r)
hit = Intersection.hit(xs)
if hit is not None:
point = Ray.position(r, hit.t)
normal = shape.normal_at(point)
eye = -r.direction
color = PointLight.lighting(hit.object.material, hit.object,
light, point, eye, normal, False)
canvas.write_pixel(x, y, color)
canvas.canvas_to_ppm()