def test_diffuse_BRDF_function(x_axis, y_axis, z_axis):
for i in range(NUM_ITERS):
incident = random_hemisphere_uniform_weighted(x_axis, y_axis, z_axis)
exitant = random_hemisphere_uniform_weighted(x_axis, y_axis, z_axis)
assert BRDF_function(Material.DIFFUSE.value, incident, z_axis, exitant,
Direction.FROM_CAMERA.value) > 0
def test_diffuse_BRDF_function_sign_issues(x_axis, y_axis, z_axis):
for i in range(NUM_ITERS):
incident = random_hemisphere_uniform_weighted(x_axis, y_axis, z_axis)
exitant = random_hemisphere_uniform_weighted(x_axis, y_axis, z_axis)
# negative BRDF_function values come from directions pointing into the point rather than away
assert BRDF_function(Material.DIFFUSE.value, incident, z_axis,
-1 * exitant, Direction.FROM_CAMERA.value) < 0
assert BRDF_function(Material.DIFFUSE.value, -1 * incident, z_axis,
exitant, Direction.FROM_EMITTER.value) < 0
def test_diffuse_BRDF_pdf_sign_issues(x_axis, y_axis, z_axis):
for i in range(NUM_ITERS):
incident = random_hemisphere_uniform_weighted(x_axis, y_axis,
-1 * z_axis)
exitant = random_hemisphere_uniform_weighted(x_axis, y_axis,
-1 * z_axis)
assert BRDF_pdf(Material.DIFFUSE.value, incident, z_axis, exitant,
Direction.FROM_CAMERA.value) < 0
# brdf from emitter is constant and is never negative
assert BRDF_pdf(Material.DIFFUSE.value, incident, z_axis, exitant,
Direction.FROM_EMITTER.value) > 0
def test_diffuse_BRDF_sample_bad_normal(x_axis, y_axis, z_axis):
incident = random_hemisphere_uniform_weighted(x_axis, y_axis, z_axis)
exitant = BRDF_sample(Material.DIFFUSE.value, incident, -1 * z_axis,
Direction.FROM_CAMERA.value)
# wrong-sided normal direction WILL (obviously) affect right-sidedness of output
assert np.dot(exitant, z_axis) <= 0
def test_diffuse_BRDF_sample_bad_incident(x_axis, y_axis, z_axis):
incident = random_hemisphere_uniform_weighted(x_axis, y_axis, -1 * z_axis)
exitant = BRDF_sample(Material.DIFFUSE.value, incident, z_axis,
Direction.FROM_CAMERA.value)
# wrong-sided incident direction will NOT affect right-sidedness of output
assert np.dot(exitant, z_axis) >= 0
def test_diffuse_BRDF_sample(x_axis, y_axis, z_axis):
for _ in range(NUM_ITERS):
incident = random_hemisphere_uniform_weighted(x_axis, y_axis, z_axis)
exitant = BRDF_sample(Material.DIFFUSE.value, incident, z_axis,
Direction.FROM_CAMERA.value)
assert np.dot(exitant, z_axis) >= 0
def test_specular_reflection_wrong_side(x_axis, y_axis, z_axis):
# the specular reflection function doesn't care which side of the normal you're on.
for _ in range(NUM_ITERS):
incident = random_hemisphere_uniform_weighted(x_axis, y_axis,
-1 * z_axis)
exitant = specular_reflection(incident, z_axis)
assert np.isclose(np.dot(incident, -1 * z_axis),
np.dot(exitant, -1 * z_axis))
def test_random_orthonormal(z_axis):
for _ in range(NUM_ITERS):
random_z = random_hemisphere_uniform_weighted(
*local_orthonormal_system(z_axis))
x, y, z = local_orthonormal_system(random_z)
assert np.isclose(np.dot(x, y), 0)
assert np.isclose(np.dot(y, z), 0)
assert np.isclose(np.dot(x, z), 0)
assert (z == random_z).all()
def test_specular_reflection(x_axis, y_axis, z_axis):
for _ in range(NUM_ITERS):
incident = random_hemisphere_uniform_weighted(x_axis, y_axis, z_axis)
exitant = specular_reflection(incident, z_axis)
in_angle = np.dot(incident, z_axis)
out_angle = np.dot(exitant, z_axis)
assert np.isclose(in_angle, out_angle)
# all 3 should be coplanar
assert np.isclose(
np.linalg.det(np.dstack([incident, z_axis, exitant])), 0)
assert (specular_reflection(x_axis, z_axis) == -1 * x_axis).all()
assert (specular_reflection(y_axis, z_axis) == -1 * y_axis).all()
def test_nonnegative_dot_product_uniform(x_axis, y_axis, z_axis):
for _ in range(NUM_ITERS):
d = random_hemisphere_uniform_weighted(x_axis, y_axis, z_axis)
assert np.dot(d, z_axis) >= 0
