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 __init__(self,
t=0.0,
p=v.vec3(0.0, 0.0, 0.0),
normal=v.vec3(0.0, 0.0, 0.0)):
self.t = t # float
self.p = p # vec3
self.normal = normal # vec3
self.material = None # material class instance
def random_in_unit_sphere():
'''
Random rays.
Returns: vec3
'''
pt = v.vec3(0.0, 0.0, 0.0)
while True:
pt = 2.0 * v.vec3(random.random(), random.random(), random.random()) - v.vec3(1, 1, 1)
if pt.squared_length() >= 1.0:
break
return pt
def random_in_unit_disk():
'''
Random rays.
Returns: vec3
'''
pt = v.vec3(0.0, 0.0, 0.0)
while True:
pt = 2.0 * v.vec3(random.random(), random.random(), 0) - v.vec3(
1, 1, 0)
if pt.dot_product(pt) >= 1.0:
break
return pt
def main():
'''
Write a ppm file.
'''
world = build_scene()
nx = 200
ny = 100
ns = 100
look_from = v.vec3(13, 2, 3)
look_at = v.vec3(0, 0, 0)
dist_to_focus = 10 # was abs(look_from - look_at)
aperture = 0.1
cam1 = c.camera(look_from, look_at, v.vec3(0, 1, 0), 20, nx / ny, aperture,
dist_to_focus)
output_file = 'out.ppm'
f = open(output_file, 'w')
f.write('P3\n' + str(nx) + ' ' + str(ny) + '\n255\n')
for j in range(ny - 1, -1, -1):
for i in range(0, nx):
col = v.vec3(0, 0, 0)
for k in range(0, ns):
u_coord = (
i + random.random()) / nx # 0.0 <= random.random() < 1.0
v_coord = (j + random.random()) / ny
this_ray = cam1.get_ray(u_coord, v_coord)
col = col + colour(this_ray, world, 0)
col = col / ns
col = v.vec3(np.sqrt(col[0]), np.sqrt(col[1]),
np.sqrt(col[2])) # gamma correction
ir = int(255.99 * col[0])
ig = int(255.99 * col[1])
ib = int(255.99 * col[2])
f.write(str(ir) + ' ' + str(ig) + ' ' + str(ib) + '\n')
f.close()
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 build_scene():
scene = []
scene.append(
s.sphere(v.vec3(0, -1000, 0), 1000, m.Lambert(v.vec3(0.5, 0.5, 0.5))))
# ranges were -11 to 11
for a in range(-4, 4, 1): # start, stop, step
for b in range(-4, 4, 1): # start, stop, step
choose_mat = random.random()
centre = v.vec3(a + 0.9 * random.random(), 0.2,
b + 0.9 * random.random())
if abs(centre - v.vec3(4, 0.2, 0)) > 0.9:
if choose_mat < 0.8: # diffuse
scene.append(
s.sphere(
centre, 0.2,
m.Lambert(
v.vec3(random.random(), random.random(),
random.random()))))
elif choose_mat < 0.95: # metal
scene.append(
s.sphere(
centre, 0.2,
m.Metal(
v.vec3(0.5 * (1 + random.random()),
0.5 * (1 + random.random()),
0.5 * (1 + random.random())),
0.5 * random.random())))
else:
scene.append(s.sphere(centre, 0.2, m.Dielectric(1.5)))
scene.append(s.sphere(v.vec3(0, 1, 0), 1.0, m.Dielectric(1.5)))
scene.append(
s.sphere(v.vec3(-4, 1, 0), 1.0, m.Lambert(v.vec3(0.4, 0.2, 0.1))))
scene.append(
s.sphere(v.vec3(4, 1, -1), 1.0, m.Metal(v.vec3(0.7, 0.6, 0.5), 0.0)))
return Hitable_List(scene)