def local_normal_at(self, local_point, hit=None):
if self.smoothed:
return add(
multiply(self.n2, hit.u),
add(multiply(self.n3, hit.v),
multiply(self.n1, (1 - hit.u - hit.v))))
return self.normal
def __init__(self, corner, full_uvec, usteps, full_vvec, vsteps,
intensity):
self.corner = corner
self.uvec = multiply(full_uvec, 1 / usteps)
self.usteps = usteps
self.vvec = multiply(full_vvec, 1 / vsteps)
self.vsteps = vsteps
self.samples = usteps * vsteps
self.position = add(add(corner, multiply(full_uvec, 1 / 2)),
multiply(full_vvec, 1 / 2))
self.intensity = intensity
self.jitter_by = DeterministicSequence([0.5])
def reflected_color(self, hit, remaining=5):
if remaining <= 0:
return color(0, 0, 0)
if hit.object.material.reflective == 0.0:
return color(0, 0, 0)
reflect_ray = Ray(hit.over_point, hit.reflectv)
reflect_color = self.color_at(reflect_ray, remaining - 1)
return multiply(reflect_color, hit.object.material.reflective)
def shade_hit(self, hit, remaining=5):
surface = color(0, 0, 0)
for light in self.lights:
light_intensity = light.intensity_at(hit.over_point, self)
surface = add(
surface,
lighting(hit.object.material, hit.object, light, hit.point,
hit.eyev, hit.normalv, light_intensity))
reflected = self.reflected_color(hit, remaining)
refracted = self.refracted_color(hit, remaining)
material = hit.object.material
if material.reflective > 0 and material.transparency > 0:
reflectance = hit.schlick()
return add(add(surface, multiply(reflected, reflectance)),
multiply(refracted, (1 - reflectance)))
return add(add(surface, reflected), refracted)
def refracted_color(self, hit, remaining=5):
if remaining <= 0:
return color(0, 0, 0)
if hit.object.material.transparency == 0.0:
return color(0, 0, 0)
n_ratio = hit.n1 / hit.n2
cos_i = dot(hit.eyev, hit.normalv)
sin2_t = n_ratio**2 * (1 - cos_i**2)
if sin2_t > 1.0:
return color(0, 0, 0)
cos_t = sqrt(1.0 - sin2_t)
direction = subtract(multiply(hit.normalv, (n_ratio * cos_i - cos_t)),
multiply(hit.eyev, n_ratio))
refract_ray = Ray(hit.under_point, direction)
return multiply(self.color_at(refract_ray, remaining - 1),
hit.object.material.transparency)
def main():
p = dict(position=point(0, 1, 0),
velocity=multiply(normalize(vector(1, 1.8, 0)), 11.25))
e = dict(gravity=vector(0, -0.1, 0), wind=vector(-0.01, 0, 0))
c = Canvas(900, 550)
while p['position'][1] > 0.0:
print(
f"position {p['position'][0]}, {p['position'][1]}, {p['position'][2]}"
)
c.set_pixel(round(p['position'][0]),
c.height - round(p['position'][1]), color(0.0, 1.0, 0.0))
p = tick(e, p)
with open('cannon.ppm', 'w') as out_file:
out_file.write(c.to_ppm())
def step_impl(context):
assert multiply(context.c, 2) == color(0.4, 0.6, 0.8)
def point_on_light(self, u, v):
return add(self.corner, \
add(multiply(self.uvec, (u + self.jitter_by.next())), \
multiply(self.vvec, (v + self.jitter_by.next()))))
def pattern_at(self, point):
distance = subtract(self.color_b, self.color_a)
fraction = point[0] - floor(point[0])
return add(self.color_a, multiply(distance, fraction))