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/*
* ANISE Toolkit
* Copyright (C) 2021-onward Christopher Rabotin <christopher.rabotin@gmail.com> et al. (cf. AUTHORS.md)
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/.
*
* Documentation: https://nyxspace.com/
*/
use hifitime::Epoch;
use snafu::ensure;
use super::{NoOrientationsLoadedSnafu, OrientationError};
use crate::NaifId;
use crate::almanac::Almanac;
use crate::constants::orientations::{ECLIPJ2000, ICRS, J2000};
use crate::frames::{DynamicFrame, Frame};
use crate::naif::daf::{DAFError, NAIFSummaryRecord};
/// **Limitation:** no translation or rotation may have more than 8 nodes.
pub const MAX_TREE_DEPTH: usize = 8;
impl Almanac {
/// Returns the root of all of the loaded orientations (BPC or planetary), typically this should be J2000.
///
/// # Algorithm
///
/// 1. For each loaded BPC, iterated in reverse order (to mimic SPICE behavior)
/// 2. For each summary record in each BPC, follow the orientation branch all the way up until the end of this BPC or until the J2000.
pub fn try_find_orientation_root(&self) -> Result<NaifId, OrientationError> {
ensure!(
self.num_loaded_bpc() > 0 || !self.planetary_data.is_empty(),
NoOrientationsLoadedSnafu
);
// The common center is the absolute minimum of all centers due to the NAIF numbering.
let mut common_center = i32::MAX;
for bpc in self.bpc_data.values().rev() {
for these_summaries in bpc.iter_summary_blocks().flatten() {
for summary in these_summaries {
// This summary exists, so we need to follow the branch of centers up the tree.
if !summary.is_empty() && summary.inertial_frame_id.abs() < common_center.abs()
{
common_center = summary.inertial_frame_id;
if common_center == J2000 {
// there is nothing higher up
return Ok(common_center);
}
}
}
}
}
// If we reached this point, it means that we didn't find J2000 in the loaded BPCs, so let's iterate through the planetary data
for data in self.planetary_data.values().rev() {
for id in data.lut.by_id.keys() {
if let Ok(pc) = data.get_by_id(*id)
&& pc.parent_id < common_center
{
common_center = pc.parent_id;
if common_center == J2000 {
// there is nothing higher up
return Ok(common_center);
}
}
}
}
if common_center == ECLIPJ2000 || common_center == ICRS {
// Rotation from ecliptic J2000 / ICRS to J2000 is embedded.
common_center = J2000;
}
Ok(common_center)
}
/// Try to construct the path from the source frame all the way to the root orientation of this context.
pub fn orientation_path_to_root(
&self,
source: Frame,
epoch: Epoch,
) -> Result<(usize, [Option<NaifId>; MAX_TREE_DEPTH]), OrientationError> {
let common_center = self.try_find_orientation_root()?;
// Build a tree, set a fixed depth to avoid allocations
let mut of_path = [None; MAX_TREE_DEPTH];
let mut of_path_len = 0;
if common_center == source.orientation_id {
// We're querying the source, no need to check that this summary even exists.
return Ok((of_path_len, of_path));
}
// Grab the summary data, which we use to find the paths
// Let's see if this orientation is defined in the loaded BPC files
let mut inertial_frame_id = if source.orient_origin_id_match(ICRS) {
J2000
} else if let Ok(dyn_frame) = DynamicFrame::try_from(source.orientation_id as u32)
&& matches!(
dyn_frame,
DynamicFrame::EarthMeanOfDate { .. }
| DynamicFrame::EarthTrueOfDate { .. }
| DynamicFrame::EarthTrueEquatorMeanEquinox { .. }
)
{
match dyn_frame {
DynamicFrame::EarthMeanOfDate { precession }
| DynamicFrame::EarthTrueOfDate { precession, .. }
| DynamicFrame::EarthTrueEquatorMeanEquinox { precession, .. } => {
precession.parent_id()
}
_ => unreachable!(),
}
} else {
let orientation_id =
if let Ok(dyn_frame) = DynamicFrame::try_from(source.orientation_id as u32) {
match dyn_frame {
DynamicFrame::BodyMeanOfDate { source_id }
| DynamicFrame::BodyTrueOfDate { source_id } => source_id,
_ => unreachable!("all other variants handled above"),
}
} else {
source.orientation_id
};
match self.bpc_summary_at_epoch(orientation_id, epoch) {
Ok((summary, _, _, _)) => summary.inertial_frame_id,
Err(_) => {
// Not available as a BPC, so let's see if there's planetary data for it.
match self.get_planetary_data_from_id(orientation_id) {
Ok(planetary_data) => planetary_data.parent_id,
Err(_) => {
// Finally, let's see if it's in the loaded Euler Parameters.
self.euler_param_from_id(orientation_id)?.to
}
}
}
}
};
of_path[of_path_len] = Some(inertial_frame_id);
of_path_len += 1;
// Hop the embedded constant rotations up to the common root.
// Future embedded constant-rotation parents should be added here.
if inertial_frame_id == ECLIPJ2000 || inertial_frame_id == ICRS {
inertial_frame_id = J2000;
of_path[of_path_len] = Some(inertial_frame_id);
of_path_len += 1;
}
if inertial_frame_id == common_center {
// Well that was quick!
return Ok((of_path_len, of_path));
}
for _ in 0..MAX_TREE_DEPTH - 1 {
inertial_frame_id = match self.bpc_summary_at_epoch(inertial_frame_id, epoch) {
Ok((summary, _, _, _)) => summary.inertial_frame_id,
Err(_) => {
// Not available as a BPC, so let's see if there's planetary data for it.
match self.get_planetary_data_from_id(inertial_frame_id) {
Ok(planetary_data) => planetary_data.parent_id,
Err(_) => {
// Finally, let's see if it's in the loaded Euler Parameters.
self.euler_param_from_id(inertial_frame_id)?.to
}
}
}
};
of_path[of_path_len] = Some(inertial_frame_id);
of_path_len += 1;
if inertial_frame_id == common_center {
// We're found the path!
return Ok((of_path_len, of_path));
}
}
Err(OrientationError::BPC {
action: "computing path to common node",
source: DAFError::MaxRecursionDepth,
})
}
/// Returns the orientation path between two frames and the common node. This may return a `DisjointRoots` error if the frames do not share a common root, which is considered a file integrity error.
pub fn common_orientation_path(
&self,
from_frame: Frame,
to_frame: Frame,
epoch: Epoch,
) -> Result<(usize, [Option<NaifId>; MAX_TREE_DEPTH], NaifId), OrientationError> {
if from_frame == to_frame {
// Both frames match, return this frame's hash (i.e. no need to go higher up).
return Ok((0, [None; MAX_TREE_DEPTH], from_frame.orientation_id));
}
// Grab the paths
let (from_len, from_path) = self.orientation_path_to_root(from_frame, epoch)?;
let (to_len, to_path) = self.orientation_path_to_root(to_frame, epoch)?;
// Now that we have the paths, we can find the matching origin.
// If either path is of zero length, that means one of them is at the root of this ANISE file, so the common
// path is which brings the non zero-length path back to the file root.
if from_len == 0 && to_len == 0 {
Err(OrientationError::RotationOrigin {
from: from_frame.into(),
to: to_frame.into(),
epoch,
})
} else if from_len != 0 && to_len == 0 {
// One has an empty path but not the other, so the root is at the empty path
Ok((from_len, from_path, to_frame.orientation_id))
} else if to_len != 0 && from_len == 0 {
// One has an empty path but not the other, so the root is at the empty path
Ok((to_len, to_path, from_frame.orientation_id))
} else {
// Either are at the orientation root, so we'll step through the paths until we find the common root.
let mut common_path = to_path;
let mut items: usize = to_len;
let common_node = to_path[to_len - 1].expect("path entry within to_len must be Some");
for from_obj in from_path.iter().take(from_len).rev().skip(1) {
common_path[items] =
Some(from_obj.expect("path entry within from_len must be Some"));
items += 1;
}
Ok((items, common_path, common_node))
}
}
}