"""基于 ``CoordinateSystem`` 的 synodic ↔ J2000 转换器。
synodic 坐标系 = (SynodicAxes, CelestialBodyOrigin("EARTH"))
J2000 坐标系 = (ICRSAxes, CelestialBodyOrigin("EARTH"))
二者原点相同 (地心) 因此 ``CoordinateSystem.transform_state`` 仅旋转轴向；
无量纲 synodic 状态在调用前后通过 ``l_c`` / ``t_c`` 量纲化与无量纲化。
"""
from __future__ import annotations
import numpy as np
import numpy.typing as npt
from ...data.constants import SECONDS_PER_DAY
from ..dynamics.cr3bp_system import CR3BP_System
from .coordinate_system import CoordinateSystem
from .standard_axes import ICRSAxes
from .standard_origins import CelestialBodyOrigin
from .synodic_axes import SynodicAxes
_TU_SECONDS_DEFAULT = 4.34811305 * SECONDS_PER_DAY
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class SynodicJ2000System:
"""基于 ``CoordinateSystem`` 的 synodic ↔ J2000 转换器。"""
def __init__(self, cr3bp_system: CR3BP_System, spice) -> None:
self.cr3bp_system = cr3bp_system
self.spice = spice
self.synodic_axes = SynodicAxes(spice)
earth_origin = CelestialBodyOrigin("EARTH", spice)
self.synodic_cs = CoordinateSystem(self.synodic_axes, earth_origin)
self.j2000_cs = CoordinateSystem(ICRSAxes(), earth_origin)
def _get_time_unit(self) -> float:
if (
hasattr(self.cr3bp_system, "characteristic_time")
and self.cr3bp_system.characteristic_time is not None
):
return self.cr3bp_system.characteristic_time
return _TU_SECONDS_DEFAULT
@staticmethod
def _bary_to_earth_offset(mu: float) -> npt.NDArray[np.floating]:
return np.array([mu, 0.0, 0.0])
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def synodic_to_j2000(
self, state_syn: npt.ArrayLike, t_syn: float, et0: float
) -> npt.NDArray[np.floating]:
state_syn = np.asarray(state_syn, dtype=float)
mu = self.cr3bp_system.mu
t_c = self._get_time_unit()
et = et0 + t_syn * t_c
l_c = self.synodic_axes.characteristic_length(et)
# 把无量纲"质心系"位置先平移到"地心 + moon-earth 轴"位置描述
offset = self._bary_to_earth_offset(mu)
position_in = (state_syn[:3] + offset) * l_c
velocity_in = state_syn[3:] * l_c / t_c
state_in = np.concatenate([position_in, velocity_in])
return self.j2000_cs.transform_state(state_in, self.synodic_cs, self.j2000_cs, et)
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def j2000_to_synodic(
self, state_j2000: npt.ArrayLike, t_syn: float, et0: float
) -> npt.NDArray[np.floating]:
state_j2000 = np.asarray(state_j2000, dtype=float)
mu = self.cr3bp_system.mu
t_c = self._get_time_unit()
et = et0 + t_syn * t_c
l_c = self.synodic_axes.characteristic_length(et)
state_earth_syn = self.synodic_cs.transform_state(
state_j2000, self.j2000_cs, self.synodic_cs, et
)
offset = self._bary_to_earth_offset(mu)
r_syn = state_earth_syn[:3] / l_c - offset
v_syn = state_earth_syn[3:] * t_c / l_c
return np.concatenate([r_syn, v_syn])
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def batch_synodic_to_j2000(
self,
states_syn: npt.ArrayLike,
t_syn_arr: npt.ArrayLike,
et0: float,
) -> npt.NDArray[np.floating]:
"""批量 synodic→J2000（下沉 Rust，逐位对齐逐点版）。"""
from e2m2e.integrators import batch_synodic_to_j2000_py, require_rust_extension
require_rust_extension("batch_synodic_to_j2000_py")
states_syn = np.asarray(states_syn, dtype=float)
t_syn_arr = np.asarray(t_syn_arr, dtype=float)
n = len(t_syn_arr)
flat = batch_synodic_to_j2000_py(
states_syn.ravel().tolist(),
t_syn_arr.ravel().tolist(),
float(et0),
float(self.cr3bp_system.mu),
float(self._get_time_unit()),
)
return np.asarray(flat, dtype=float).reshape(n, 6)
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def batch_j2000_to_synodic(
self,
states_j2000: npt.ArrayLike,
t_syn_arr: npt.ArrayLike,
et0: float,
) -> npt.NDArray[np.floating]:
"""批量 J2000→synodic（下沉 Rust，逐位对齐逐点版）。"""
from e2m2e.integrators import batch_j2000_to_synodic_py, require_rust_extension
require_rust_extension("batch_j2000_to_synodic_py")
states_j2000 = np.asarray(states_j2000, dtype=float)
t_syn_arr = np.asarray(t_syn_arr, dtype=float)
n = len(t_syn_arr)
flat = batch_j2000_to_synodic_py(
states_j2000.ravel().tolist(),
t_syn_arr.ravel().tolist(),
float(et0),
float(self.cr3bp_system.mu),
float(self._get_time_unit()),
)
return np.asarray(flat, dtype=float).reshape(n, 6)