def scatter(self, r_in, rec):
reflected = reflect(r_in.direction(), rec.record[2])
attenuation = vec3(1.0, 1.0, 1.0)
if (vec3.dot(r_in.direction(), rec.record[2]) > 0):
outworld_normal = -rec.record[2]
ni_over_nt = self.ref_idx
cosine = self.ref_idx * vec3.dot(r_in.direction(), rec.record[2]) / r_in.direction().length()
else:
outworld_normal = rec.record[2]
ni_over_nt = 1.0 / self.ref_idx
cosine = -vec3.dot(r_in.direction(), rec.record[2]) / r_in.direction().length()
isok, refracted = refract(r_in.direction(), outworld_normal, ni_over_nt)
if isok:
reflect_prob = schlick(cosine, self.ref_idx)
else:
reflect_prob = 1.0
if random.random() < reflect_prob:
scattered = ray(rec.record[1], reflected)
else:
scattered = ray(rec.record[1], refracted)
return True, scattered, attenuation
def hit_sphere(center, radius, r):
oc = r.origin - center
a = vec3.dot(r.direction, r.direction)
b = 2.0 * vec3.dot(oc, r.direction)
c = vec3.dot(oc, oc) - radius * radius
discriminat = b * b - 4 * a * c
if discriminat < 0:
return -1.0
else:
return (-b - math.sqrt(discriminat)) / (2.0 * a)
def refract(v, n, ni_over_nt):
uv = vec3.unit_vector(v)
dt = vec3.dot(uv, n)
discriminant = 1.0 - ni_over_nt*ni_over_nt*(1-dt*dt)
refracted = vec3(0, 0, 0)
if discriminant > 0:
refracted = ni_over_nt*(uv - n*dt) - n*math.sqrt(discriminant)
return True, refracted
else:
return False, refracted
def hit(self, r, t_min, t_max, rec):
oc = r.origin() - self.center
a = vec3.dot(r.direction(), r.direction())
b = vec3.dot(oc, r.direction())
c = vec3.dot(oc, oc) - self.radius * self.radius
discriminant = b * b - a * c
if discriminant > 0:
temp = (-b - math.sqrt(discriminant)) / a
if temp < t_max and temp > t_min:
rec.record[0] = temp
rec.record[1] = r.point_at_parameter(rec.record[0])
rec.record[2] = (rec.record[1] - self.center) / self.radius
rec.record[3] = self.mat
return True
temp = (-b + math.sqrt(discriminant)) / a
if temp < t_max and temp > t_min:
rec.record[0] = temp
rec.record[1] = r.point_at_parameter(rec.record[0])
rec.record[2] = (rec.record[1] - self.center) / self.radius
rec.record[3] = self.mat
return True
return False
def random_in_unit_disk():
while True:
p = 2.0 * vec3(random.random(), random.random(), 0) - vec3(1, 1, 0)
if vec3.dot(p, p) < 1:
break
return p
def reflect(v, n):
if isinstance(v, vec3) and isinstance(n, vec3):
return v - 2*vec3.dot(v, n)*n
else:
return NotImplemented
def scatter(self, r_in, rec):
reflected = reflect(vec3.unit_vector(r_in.direction()), rec.record[2])
scattered = ray(rec.record[1], reflected + self.fuzz*random_in_unit_sphere())
isok = (vec3.dot(scattered.direction(), rec.record[2]) > 0)
return isok, scattered, self.albedo