from __future__ import annotations
import attrs
import mitsuba as mi
from ._core import BSDF
from ..core import traverse
from ..spectra import Spectrum, spectrum_factory
from ... import validators
from ...attrs import define, documented
from ...kernel import TypeIdLookupStrategy, UpdateParameter
[docs]
@define(eq=False, slots=False)
class HapkeBSDF(BSDF):
"""
Hapke BSDF [``hapke``].
This BSDF implements the Hapke surface model as described in
:cite:`Hapke1984BidirectionalReflectanceSpectroscopy`. This highly flexible
and robust surface model allows for the characterisation of a sharp
back-scattering hot spot. The so-called Hapke model has been adapted to
several different use cases in the litterature, the version with 6
parameters implemented here is one of the most commonly used.
See Also
--------
:ref:`plugin-bsdf-hapke`
"""
w: Spectrum = documented(
attrs.field(
default=None,
converter=spectrum_factory.converter("dimensionless"),
validator=[
attrs.validators.instance_of(Spectrum),
validators.has_quantity("dimensionless"),
],
),
doc="Single scattering albedo 'w'. Must be in [0; 1]",
type=".Spectrum",
init_type=".Spectrum or dict or float",
)
b: Spectrum = documented(
attrs.field(
default=None,
converter=spectrum_factory.converter("dimensionless"),
validator=[
attrs.validators.instance_of(Spectrum),
validators.has_quantity("dimensionless"),
],
),
doc="Anisotropy parameter 'b' Must be in [0; 1]",
type=".Spectrum",
init_type=".Spectrum or dict or float",
)
c: Spectrum | None = documented(
attrs.field(
default=None,
converter=spectrum_factory.converter("dimensionless"),
validator=[
attrs.validators.instance_of(Spectrum),
validators.has_quantity("dimensionless"),
],
),
doc="Scattering coefficient 'c'. Must be in [0; 1]",
type=".Spectrum",
init_type=".Spectrum or dict or float",
)
theta: Spectrum = documented(
attrs.field(
default=0.183,
converter=spectrum_factory.converter("angle"),
validator=[
attrs.validators.instance_of(Spectrum),
validators.has_quantity("angle"),
],
),
doc="Photometric roughness 'theta'. Angle in degree. Must be in [0; 90]°",
type=".Spectrum",
init_type="quantity or float",
)
B_0: Spectrum = documented(
attrs.field(
default=None,
converter=spectrum_factory.converter("dimensionless"),
validator=[
attrs.validators.instance_of(Spectrum),
validators.has_quantity("dimensionless"),
],
),
doc="Shadow hiding opposition effect amplitude 'B_0'. Must be in [0; 1]",
type=".Spectrum",
init_type=".Spectrum or dict or float",
)
h: Spectrum = documented(
attrs.field(
default=None,
converter=spectrum_factory.converter("dimensionless"),
validator=[
attrs.validators.instance_of(Spectrum),
validators.has_quantity("dimensionless"),
],
),
doc="shadow hiding opposition effect width 'h'. Must be in [0; 1]",
type=".Spectrum",
init_type=".Spectrum or dict or float",
)
@property
def template(self) -> dict:
# Inherit docstring
objects = {
"w": traverse(self.w)[0],
"b": traverse(self.b)[0],
"c": traverse(self.c)[0],
"theta": traverse(self.theta)[0],
"B_0": traverse(self.B_0)[0],
"h": traverse(self.h)[0],
}
result = {"type": "hapke"}
for obj_key, obj_values in objects.items():
for key, value in obj_values.items():
result[f"{obj_key}.{key}"] = value
if self.id is not None:
result["id"] = self.id
return result
@property
def params(self) -> dict[str, UpdateParameter]:
# Inherit docstring
objects = {
"w": traverse(self.w)[1],
"b": traverse(self.b)[1],
"c": traverse(self.c)[1],
"theta": traverse(self.theta)[1],
"B_0": traverse(self.B_0)[1],
"h": traverse(self.h)[1],
}
result = {}
for obj_key, obj_params in objects.items():
for key, param in obj_params.items():
result[f"{obj_key}.{key}"] = attrs.evolve(
param,
lookup_strategy=TypeIdLookupStrategy(
node_type=mi.BSDF,
node_id=self.id,
parameter_relpath=f"{obj_key}.{key}",
)
if self.id is not None
else None,
)
return result
