def test02_roughconductor(variant_scalar_rgb):
from mitsuba.core.xml import load_string
from mitsuba.render import BSDF, BSDFContext, SurfaceInteraction3f
from mitsuba.core import Frame3f
for alpha in [(0.3, 0.3), (0.3 + 1e-5, 0.3 - 1e-5), (0.2, 0.4)]:
alpha_u = alpha[0]
alpha_v = alpha[1]
thetas = np.linspace(0, np.pi / 2, 20)
phi = np.pi
values_ref = []
# Create conductor reference BSDF
bsdf = load_string("""<bsdf version="2.0.0" type="roughconductor">
<float name="alpha_u" value="{}"/>
<float name="alpha_v" value="{}"/>
<string name="distribution" value="beckmann"/>
<spectrum name="eta" value="0.0"/>
<spectrum name="k" value="1.0"/>
</bsdf>""".format(alpha_u, alpha_v))
theta_i = np.radians(30.0)
si = SurfaceInteraction3f()
si.p = [0, 0, 0]
si.n = [0, 0, 1]
si.wi = [np.sin(theta_i), 0, np.cos(theta_i)]
si.sh_frame = Frame3f(si.n)
ctx = BSDFContext()
for theta in thetas:
wo = [
np.sin(theta) * np.cos(phi),
np.sin(theta) * np.sin(phi),
np.cos(theta)
]
values_ref.append(bsdf.eval(ctx, si, wo=wo)[0])
# Create same BSDF as layer representation
n, ms, md = mitsuba.layer.microfacet_parameter_heuristic(
alpha_u, alpha_v, 0 + 1j)
mu, w = mitsuba.core.quad.gauss_lobatto(n)
layer = mitsuba.layer.Layer(mu, w, ms, md)
layer.set_microfacet(0 + 1j, alpha_u, alpha_v)
for i, theta in enumerate(thetas):
l_eval = layer.eval(-np.cos(theta), np.cos(theta_i)) * np.abs(
np.cos(theta))
# Values should be close (except if they are insignificantly small).
# We have less precision at grazing angles because of Fourier representation.
print(values_ref[i], l_eval)
assert values_ref[i] < 1e-5 or np.allclose(
values_ref[i], l_eval, rtol=0.05 / (np.abs(np.cos(theta))))
# Convert into BSDF storage representation
base_path = os.path.dirname(os.path.realpath(__file__)) + "/data/"
if not os.path.exists(base_path):
os.makedirs(base_path)
path = base_path + "roughconductor.bsdf"
storage = mitsuba.layer.BSDFStorage.from_layer(path, layer, 1e-8)
for i, theta in enumerate(thetas):
s_eval = storage.eval(np.cos(theta_i), -np.cos(theta))[0]
# Values should be close (except if they are insignificantly small).
# We have less precision at grazing angles because of Fourier representation.
assert values_ref[i] < 1e-5 or np.allclose(
values_ref[i], s_eval, rtol=0.05 / (np.abs(np.cos(theta))))
storage.close()
# And load via the "fourier" BSDF plugin
fourier = load_string("""<bsdf version="2.0.0" type="fourier">
<string name="filename" value="{}"/>
</bsdf>""".format(path))
for i, theta in enumerate(thetas):
wo = [
np.sin(theta) * np.cos(phi),
np.sin(theta) * np.sin(phi),
np.cos(theta)
]
f_eval = fourier.eval(ctx, si, wo=wo)[0]
assert values_ref[i] < 1e-5 or np.allclose(
values_ref[i], f_eval, rtol=0.05 / (np.abs(np.cos(theta))))
del fourier
alpha_v = 0.2
eta = 0+1j
n, ms, md = mitsuba.layer.microfacet_parameter_heuristic(alpha_u, alpha_v, eta)
mu, w = mitsuba.core.quad.gauss_lobatto(n)
print(n, ms, md)
print("")
for s in [1, 3, 9]:
if s > ms:
break
print('ms: ', s)
layer = mitsuba.layer.Layer(mu, w, s, md)
layer.set_microfacet(eta, alpha_u, alpha_v)
layer.clear_backside()
filename = "%.02f_%.02f_%02d.bsdf" % (alpha_u, alpha_v, s)
storage = mitsuba.layer.BSDFStorage.from_layer(filename, layer, 1e-8)
# Example 2: Extreme anisotropy
alpha_u = 0.05
alpha_v = 0.4
eta = 0+1j
n, ms, md = mitsuba.layer.microfacet_parameter_heuristic(alpha_u, alpha_v, eta)
mu, w = mitsuba.core.quad.gauss_lobatto(n)
print(n, ms, md)
n1, ms1, md1 = mitsuba.layer.microfacet_parameter_heuristic(
alpha_u_top, alpha_v_top, eta_top)
n2, ms2, md2 = mitsuba.layer.microfacet_parameter_heuristic(
alpha_u_bot, alpha_v_bot, eta_bot[0])
n = max(n1, n2)
ms = max(ms1, ms2)
md = md2
mu, w = mitsuba.core.quad.gauss_lobatto(n)
print(" dielectric top")
dielectric = mitsuba.layer.Layer(mu, w, ms, md)
dielectric.set_microfacet(eta_top, alpha_u_top, alpha_v_top)
channels = []
for i in range(3):
print(" gold base [%d]" % i)
layer = mitsuba.layer.Layer(mu, w, ms, md)
layer.set_microfacet(eta_bot[i], alpha_u_bot, alpha_v_bot)
layer.clear_backside()
layer.add_to_top(dielectric, epsilon=1e-6)
channels.append(layer)
print(" save")
filename = "%s.bsdf" % key
storage = mitsuba.layer.BSDFStorage.from_layer_rgb(filename, *channels, 1,
1e-4)
print("\n")