from __future__ import annotations
import mitsuba as mi
import numpy as np
import pint
import pinttr
from pinttr.util import ensure_units
from ._core import ShapeNode
from ..bsdfs import BSDF
from ..core import BoundingBox
from ...attrs import define, documented
from ...constants import EARTH_RADIUS
from ...units import unit_context_config as ucc
from ...units import unit_context_kernel as uck
from ...units import unit_registry as ureg
def _normalize(v: np.typing.ArrayLike) -> np.ndarray:
return np.array(v) / np.linalg.norm(v)
[docs]
@define(eq=False, slots=False)
class SphereShape(ShapeNode):
"""
Sphere shape [``sphere``].
This shape represents a sphere parametrized by its centre and radius.
Notes
-----
* If the `to_world` parameter is set, it will be appended to the position
and scaling defined by the `center` and `radius` parameters.
"""
center: pint.Quantity = documented(
pinttr.field(factory=lambda: [0, 0, 0], units=ucc.deferred("length")),
doc="Location of the centre of the sphere. Unit-enabled field "
"(default: ``ucc['length']``).",
type="quantity",
init_type="quantity or array-like, optional",
default="[0, 0, 0]",
)
radius: pint.Quantity = documented(
pinttr.field(
factory=lambda: 1.0 * ucc.get("length"), units=ucc.deferred("length")
),
doc="Sphere radius. Unit-enabled field (default: ``ucc['length']``).",
type="quantity",
init_type="quantity or float, optional",
default="1.0",
)
@property
def bbox(self) -> BoundingBox:
length_units = ucc.get("length")
if self.to_world is not None:
trafo = (
self.to_world
@ mi.Transform4f.translate(self.center.m_as(length_units))
@ mi.Transform4f.scale(self.radius.m_as(length_units))
)
else:
trafo = mi.Transform4f.translate(
self.center.m_as(length_units)
) @ mi.Transform4f.scale(self.radius.m_as(length_units))
c = trafo @ (0, 0, 0)
r = np.linalg.norm(trafo @ (1, 0, 0) - c)
p1 = pint.Quantity(np.array(c + np.array((-1, -1, -1)) * r), length_units)
p2 = pint.Quantity(np.array(c + np.array((1, 1, 1)) * r), length_units)
return BoundingBox(p1, p2)
@property
def template(self) -> dict:
result = {
"type": "sphere",
"center": self.center.m_as(uck.get("length")),
"radius": self.radius.m_as(uck.get("length")),
}
if self.to_world is not None:
result["to_world"] = self.to_world
return result
[docs]
def contains(self, p: np.typing.ArrayLike, strict: bool = False) -> bool:
"""
Test whether a point lies within the sphere.
Parameters
----------
p : quantity or array-like
An array of shape (3,) (resp. (N, 3)) representing one (resp. N)
points. If a unitless value is passed, it is interpreted as
``ucc['length']``.
strict : bool
If ``True``, comparison is done using strict inequalities (<, >).
Returns
-------
result : array of bool or bool
``True`` iff ``p`` in within the sphere.
"""
length_units = ucc.get("length")
if self.to_world is not None:
trafo = (
self.to_world
[docs]
@ mi.Transform4f.translate(self.center.m_as(length_units))
@ mi.Transform4f.scale(self.radius.m_as(length_units))
)
else:
trafo = mi.Transform4f.translate(
self.center.m_as(length_units)
) @ mi.Transform4f.scale(self.radius.m_as(length_units))
p = np.atleast_2d(ensure_units(p, ucc.get("length")).m_as(length_units))
c = trafo @ (0, 0, 0)
d = np.linalg.norm(p - c, axis=1)
r = np.linalg.norm(trafo @ (1, 0, 0) - c)
return d < r if strict else d <= r
@classmethod
def surface(
cls,
altitude=0.0 * ureg.km,
planet_radius: pint.Quantity = EARTH_RADIUS,
bsdf: BSDF | None = None,
) -> SphereShape:
"""
This class method constructor provides a simplified parametrization of
the sphere shape better suited for the definition of the surface when
configuring the one-dimensional model.
The resulting sphere shape is centred at [0, 0, -`planet_radius`] and
has a radius equal to `planet_radius` + `altitude`.
Parameters
----------
altitude : quantity or array-like, optional, default: 0 km
Surface altitude. If a unitless value is passed, it is interpreted
as ``ucc['length']``.
planet_radius : quantity or float, optional
Planet radius. If a unitless value is passed, it is interpreted
as ``ucc['length']``. The default is Earth's radius.
bsdf : BSDF or dict, optional, default: None
A BSDF specification, forwarded to the main constructor.
Returns
-------
SphereShape
A sphere shape which can be used as the surface in a spherical shell
geometry.
"""
altitude = pinttr.util.ensure_units(altitude, default_units=ucc.get("length"))
planet_radius = pinttr.util.ensure_units(
planet_radius, default_units=ucc.get("length")
)
return cls(
center=[0.0, 0.0, 0.0] * planet_radius.units,
radius=planet_radius + altitude,
bsdf=bsdf,
)
[docs]
@classmethod
def atmosphere(
cls,
top: pint.Quantity = 100.0 * ureg.km,
planet_radius: pint.Quantity = EARTH_RADIUS,
bsdf: BSDF | None = None,
) -> SphereShape:
"""
This class method constructor provides a simplified parametrization of
the sphere shape better suited for the definition of the surface when
configuring the one-dimensional model.
The resulting sphere shape is centred at [0, 0, 0] and
has a radius equal to `planet_radius` + `top`.
Parameters
----------
top : quantity or array-like, optional, default: 100 km
Top-of-atmosphere altitude. If a unitless value is passed, it is
interpreted as ``ucc['length']``.
planet_radius : quantity or float, optional
Planet radius. If a unitless value is passed, it is interpreted
as ``ucc['length']``. The default is Earth's radius.
bsdf : BSDF or dict, optional, default: None
A BSDF specification, forwarded to the main constructor.
Returns
-------
SphereShape
A sphere shape which can be used as the stencil of a participating
medium in a spherical shell geometry.
"""
top = pinttr.util.ensure_units(top, default_units=ucc.get("length"))
planet_radius = pinttr.util.ensure_units(
planet_radius, default_units=ucc.get("length")
)
return cls(
center=[0.0, 0.0, 0.0] * planet_radius.units,
radius=planet_radius + top,
bsdf=bsdf,
)
