def test_grazing_incidence(self):
"""Grazing rays are not refracted"""
dir = N.c_[[0, 0, 1]]
norm = N.c_[[0, 1, 0]]
R = optics.fresnel(dir, norm, N.r_[1.], N.r_[1.5])
self.failUnlessAlmostEqual(R, 1.) # ref [1], page 45
def test_no_reflectance(self):
"""With index of refraction = 1, no reflection"""
dir = N.c_[[0, 1, 1]]/math.sqrt(2)
norm = N.c_[[0, 1, 0]]
R = optics.fresnel(dir, norm, N.r_[1.], N.r_[1.])
self.failUnlessAlmostEqual(R, 0)
def test_normal_incidence(self):
"""Rays at normal incidence achieve predicted reflectance."""
dir = N.c_[[0, 0, 1]]
norm = dir
R = optics.fresnel(dir, norm, N.r_[1.], N.r_[1.5])
self.failUnlessAlmostEqual(R, 0.04) # ref [1], page 44