def lighting(material, obj, light, point, eyev, normalv, in_shawdow=False):
if material.pattern is not None:
c = pattern_at_shape(material.pattern, obj, point)
else:
c = material.color
effective_color = c * light.intensity
lightv = normalize(light.position - point)
ambient = effective_color * material.ambient
light_dot_normal = dot(lightv, normalv)
black = color(0, 0, 0)
if light_dot_normal < 0:
diffuse = black
specular = black
else:
diffuse = effective_color * material.diffuse * light_dot_normal
reflectv = reflect(-lightv, normalv)
reflect_dot_eye = dot(reflectv, eyev)
if reflect_dot_eye <= 0:
specular = black
else:
factor = reflect_dot_eye ** material.shininess
specular = light.intensity * material.specular * factor
if in_shawdow:
return ambient
else:
return ambient + diffuse + specular
def prepare_computations(intersection, ray, xs=None):
c = comps()
c.t = intersection.t
c.object = intersection.object
c.point = position(ray, c.t)
c.eyev = -ray.direction
c.normalv = normal_at(c.object, c.point)
if dot(c.normalv, c.eyev) < 0:
c.inside = True
c.normalv = -c.normalv
else:
c.inside = False
c.over_point = c.point + c.normalv * EPSILON
c.under_point = c.point - c.normalv * EPSILON
c.reflectv = reflect(ray.direction, c.normalv)
containers = []
if xs:
for i in xs:
if i == intersection:
if len(containers) == 0:
c.n1 = 1.0
else:
c.n1 = containers[-1].material.refractive_index
if i.object in containers:
containers.remove(i.object)
else:
containers.append(i.object)
if i == intersection:
if len(containers) == 0:
c.n2 = 1.0
else:
c.n2 = containers[-1].material.refractive_index
break
return c
def local_intersect(self, triangle, ray):
dir_cross_e2 = cross(ray.direction, triangle.e2)
det = dot(triangle.e1, dir_cross_e2)
if abs(det) < EPSILON:
return []
else:
f = 1.0 / det
p1_to_origin = ray.origin - triangle.p1
u = f * dot(p1_to_origin, dir_cross_e2)
if u < 0 or u > 1:
return []
origin_cross_e1 = cross(p1_to_origin, triangle.e1)
v = f * dot(ray.direction, origin_cross_e1)
if v < 0 or (u + v) > 1:
return []
t = f * dot(triangle.e2, origin_cross_e1)
return [intersection(t, triangle)]
def schlick(comps):
cos = dot(comps.eyev, comps.normalv)
if comps.n1 > comps.n2:
n = comps.n1 / comps.n2
sin2_t = (n ** 2) * (1.0 - cos ** 2)
if sin2_t > 1.0:
return 1.0
cos_t = sqrt(1.0 - sin2_t)
cos = cos_t
r0 = ((comps.n1 - comps.n2) / (comps.n1 + comps.n2)) ** 2
return r0 + (1 - r0) * (1 - cos) ** 5
def refracted_color(world, comps, remaining):
if comps.object.material.transparency == 0 or remaining <= 0:
return color(0, 0, 0)
else:
n_ratio = comps.n1 / comps.n2
cos_i = dot(comps.eyev, comps.normalv)
sin2_t = n_ratio ** 2 * (1 - cos_i ** 2)
if sin2_t > 1:
return color(0, 0, 0)
else:
cos_t = sqrt(1.0 - sin2_t)
direction = comps.normalv * (n_ratio * cos_i - cos_t) - comps.eyev * n_ratio
refract_ray = ray(comps.under_point, direction)
c = (
color_at(world, refract_ray, remaining - 1)
* comps.object.material.transparency
)
return c
def step_impl(context):
assert dot(context.a, context.b) == 20