def build_from_w(self, n: Vector3):
self._w = Vector3.normalize(n)
if math.fabs(self._w.x()) > 0.9:
a = Vector3(0, 1, 0)
else:
a = Vector3(1, 0, 0)
self._v = Vector3.normalize(Vector3.cross(self._w, a))
self._u = Vector3.cross(self._w, self._v)
def __init__(self, lookfrom:'Vector3', lookat:'Vector3', vectorup:'Vector3', vfov:'float', aspect:'float', aperture:'float', focus_dist:'float', t0:float, t1:float):
theta = vfov * math.pi / 180 # vfov to radians
half_height = math.tan(theta / 2) # h = tan(theta / 2)
half_width = half_height * aspect
self._lens_radius = aperture / 2
self._time0 = t0
self._time1 = t1
self._camera_origin = lookfrom
w = Vector3.normalize(lookfrom - lookat)
u = Vector3.normalize(Vector3.cross(vectorup, w))
v = Vector3.cross(w, u)
self._lower_left_corner = self._camera_origin - half_width * focus_dist * u - half_height * focus_dist * v - focus_dist*w
self._horizontal = 2 * half_width * focus_dist * u
self._vertical = 2 * half_height * focus_dist * v