nyx_space/cosmic/
eclipse.rs

1/*
2    Nyx, blazing fast astrodynamics
3    Copyright (C) 2018-onwards Christopher Rabotin <christopher.rabotin@gmail.com>
4
5    This program is free software: you can redistribute it and/or modify
6    it under the terms of the GNU Affero General Public License as published
7    by the Free Software Foundation, either version 3 of the License, or
8    (at your option) any later version.
9
10    This program is distributed in the hope that it will be useful,
11    but WITHOUT ANY WARRANTY; without even the implied warranty of
12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13    GNU Affero General Public License for more details.
14
15    You should have received a copy of the GNU Affero General Public License
16    along with this program.  If not, see <https://www.gnu.org/licenses/>.
17*/
18
19use anise::almanac::Almanac;
20use anise::analysis::prelude::Event;
21use anise::astro::Occultation;
22use anise::constants::frames::{EARTH_J2000, MOON_J2000, SUN_J2000};
23use anise::errors::AlmanacResult;
24
25pub use super::{Frame, Orbit, Spacecraft};
26use std::fmt;
27use std::sync::Arc;
28
29#[derive(Clone)]
30pub struct EclipseLocator {
31    pub light_source: Frame,
32    pub shadow_bodies: Vec<Frame>,
33}
34
35impl fmt::Display for EclipseLocator {
36    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
37        let shadow_bodies: Vec<String> = self
38            .shadow_bodies
39            .iter()
40            .map(|b| format!("{b:x}"))
41            .collect();
42        write!(
43            f,
44            "light-source: {:x}, shadows casted by: {}",
45            self.light_source,
46            shadow_bodies.join(", ")
47        )
48    }
49}
50
51impl EclipseLocator {
52    /// Creates a new typical eclipse locator.
53    /// The light source is the Sun, and the shadow bodies are the Earth and the Moon.
54    pub fn cislunar(almanac: Arc<Almanac>) -> Self {
55        let eme2k = almanac.frame_info(EARTH_J2000).unwrap();
56        let moon_j2k = almanac.frame_info(MOON_J2000).unwrap();
57        Self {
58            light_source: almanac.frame_info(SUN_J2000).unwrap(),
59            shadow_bodies: vec![eme2k, moon_j2k],
60        }
61    }
62
63    /// Compute the visibility/eclipse between an observer and an observed state
64    pub fn compute(&self, observer: Orbit, almanac: Arc<Almanac>) -> AlmanacResult<Occultation> {
65        let mut state = Occultation {
66            epoch: observer.epoch,
67            back_frame: SUN_J2000,
68            front_frame: observer.frame,
69            percentage: 0.0,
70        };
71        for eclipsing_body in &self.shadow_bodies {
72            let this_state = almanac.solar_eclipsing(*eclipsing_body, observer, None)?;
73            if this_state.percentage > state.percentage {
74                state = this_state;
75            }
76        }
77        Ok(state)
78    }
79
80    /// Creates an umbra event from this eclipse locator.
81    /// Evaluation of the event, returns 0.0 for umbra, 1.0 for visibility (no shadow) and some value in between for penumbra
82    pub fn to_umbra_events(&self) -> Vec<Event> {
83        self.shadow_bodies
84            .iter()
85            .copied()
86            .map(Event::total_eclipse)
87            .collect()
88    }
89
90    /// Creates a penumbra event from this eclipse locator
91    // Evaluation of the event, returns 0.0 for umbra, 1.0 for visibility (no shadow) and some value in between for penumbra
92    pub fn to_penumbra_events(&self) -> Vec<Event> {
93        self.shadow_bodies
94            .iter()
95            .copied()
96            .map(Event::eclipse)
97            .collect()
98    }
99}
nyx_space/cosmic/eclipse.rs

nyx_space/cosmic/
eclipse.rs
