def scatter(self, this_ray, rec, attenuation, scattered):
outward_normal = v.vec3(0.0, 0.0, 0.0)
refracted = v.vec3(0.0, 0.0, 0.0)
reflected = reflect(this_ray.direction.unit_vector(), rec.normal)
ni_over_nt = 0.0
reflect_prob = 0.0
cosine = 0.0
attenuation = v.vec3(1.0, 1.0, 1.0)
if this_ray.direction.dot_product(rec.normal) > 0:
outward_normal = -rec.normal
ni_over_nt = self.ri
cosine = self.ri * this_ray.direction.dot_product(rec.normal) / abs(this_ray.direction)
else:
outward_normal = rec.normal
ni_over_nt = 1.0 / self.ri
cosine = -this_ray.direction.dot_product(rec.normal) / abs(this_ray.direction)
refract_result = refract(this_ray.direction, outward_normal, ni_over_nt, refracted)
if refract_result[0]:
reflect_prob = schlick(cosine, self.ri)
else:
scattered = r.ray(rec.p, reflected)
reflect_prob = 1.0
if random.random() < reflect_prob:
scattered = r.ray(rec.p, reflected)
else:
scattered = r.ray(rec.p, refract_result[1])
return True, scattered, attenuation
def get_ray(self, u_coord, v_coord):
'''
Return ray at position.
'''
rd = self.lens_radius * random_in_unit_disk()
offset = self.cu * rd.x + self.cv * rd.y
return r.ray(
self.origin + offset,
self.lower_left_corner + u_coord * self.horizontal +
v_coord * self.vertical - self.origin - offset)
def colour(this_ray, world, depth):
'''
Colour pixel based on ray hit.
'''
rec = hit_record()
if world.hit(this_ray, 0.001, MAXFLOAT, rec):
scattered = r.ray(v.vec3(0.0, 0.0, 0.0), v.vec3(0.0, 0.0, 0.0))
attenuation = v.vec3(0.0, 0.0, 0.0)
hit = rec.material.scatter(this_ray, rec, attenuation, scattered)
if depth < 50 and hit[0]:
# hit 1 = scattered, hit 2 = albedo
return colour(hit[1], world,
depth + 1) * hit[2] # return coloured ray
else:
return v.vec3(0.0, 0.0, 0.0)
# blue background
unit_direction = v.vec3.unit_vector(this_ray.direction)
t = 0.5 * (unit_direction.y + 1.0)
return (1.0 - t) * v.vec3(1.0, 1.0, 1.0) + t * v.vec3(0.5, 0.7, 1.0)
def scatter(self, this_ray, rec, attenuation, scattered):
reflected = reflect(this_ray.direction.unit_vector(), rec.normal)
offset = reflected * 0.01
scattered = r.ray(rec.p, reflected + offset + self.fuzz * random_in_unit_sphere())
dot = scattered.direction.dot_product(rec.normal)
return dot > 0, scattered, self.albedo
def scatter(self, this_ray, rec, attenuation, scattered):
target = rec.p + rec.normal + random_in_unit_sphere()
scattered = r.ray(rec.p, target-rec.p)
return True, scattered, self.albedo