def get_direction(self, shading_point):
self.w = shading_point.normal
up = Vector(0.003, 1.0, 0.007)
self.v = up.cross(self.w)
self.v = self.v.normalize()
self.u = self.v.cross(self.w)
sp = self.sampler.sample_hemisphere()
self.wi = self.u.scalar(sp.x) + self.v.scalar(sp.y) + self.w.scalar(sp.z)
return self.wi.scalar(-1.0)
def sample_f(self, shading_point):
w = shading_point.normal
# jitter the up vector
v = Vector(0.0024, 1.0, 0.0081).cross(w)
v = v.normalize()
u = v.cross(w)
sample_point = self.sampler.sample_hemisphere()
wi = sample_point.x * u + sample_point.y * v + sample_point.z * w
wi = wi.normalize()
pdf = shading_point.normal * wi / math.pi
color = self.surface.get_color(shading_point)
return pdf, wi, (self.kd * color / math.pi)