def test_ray_intersects_sphere_object():
r = Ray(Point(0, 0, -5), Vector(0, 0, 1))
s = Sphere()
x = r.intersects(s)
assert len(x) == 2
assert x[0].object == s
assert x[1].object == s
def test_sphere_intersection_scaled():
r = Ray(Point(0, 0, -5), Vector(0, 0, 1))
s = Sphere()
s.set_transform(scaling(2, 2, 2))
x = r.intersects(s)
assert len(x) == 2
assert x[0].t == 3
assert x[1].t == 7
def test_ray_intersect_from_behind():
r = Ray(Point(0, 0, 5), Vector(0, 0, 1))
s = Sphere()
x = r.intersects(s)
assert len(x) == 2
assert x[0].t == -6
assert x[1].t == -4
def test_ray_intersect_from_middle():
r = Ray(Point(0, 0, 0), Vector(0, 0, 1))
s = Sphere()
x = r.intersects(s)
assert len(x) == 2
assert x[0].t == -1
assert x[1].t == 1
def test_ray_intersect_sphere_tangent():
r = Ray(Point(0, 1, -5), Vector(0, 0, 1))
s = Sphere()
x = r.intersects(s)
assert len(x) == 2
assert x[0].t == 5
assert x[1].t == 5
def test_sphere_intersection_translate():
r = Ray(Point(0, 0, -5), Vector(0, 0, 1))
s = Sphere()
s.set_transform(translation(5, 0, 0))
x = r.intersects(s)
assert len(x) == 0
def test_ray_intersect_sphere_no_intersection():
r = Ray(Point(0, 2, -5), Vector(0, 0, 1))
s = Sphere()
x = r.intersects(s)
assert len(x) == 0
from src.canvas import Canvas
from src.color import Color
from src.primitives import Sphere
from src.ray import Ray
from src.transformations import scaling, rotation_z
from src.tupl import Point
s = Sphere()
t = rotation_z(pi / 4) @ scaling(0.5, 1, 1)
s.set_transform(t)
r_origin = Point(0, 0, -5)
wall_z = 10
wall_size = 7
N = 100
c = Canvas(N, N)
pixel_size = wall_size / N
half = wall_size / 2
red = Color(255, 0, 0)
for y in range(c.height):
world_y = half - pixel_size * y
for x in range(c.width):
world_x = -half + pixel_size * x
position = Point(world_x, world_y, wall_z)
r = Ray(r_origin, (position - r_origin).normalize())
X = r.intersects(s)
if X.hit is not None:
c.write_pixel(x, y, red)
c.to_ppm('circle.ppm')