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/*
*****************************************************
*
* SaVi by Lloyd Wood (lloydwood@users.sourceforge.net),
* Patrick Worfolk (worfolk@alum.mit.edu) and
* Robert Thurman.
*
* Copyright (c) 1997 by The Geometry Center.
* Also Copyright (c) 2017 by Lloyd Wood.
*
* This file is part of SaVi. SaVi is free software;
* you can redistribute it and/or modify it only under
* the terms given in the file COPYRIGHT which you should
* have received along with this file. SaVi may be
* obtained from:
* http://savi.sourceforge.net/
* http://www.geom.uiuc.edu/locate/SaVi
*
*****************************************************
*
* Satellite.c
*
* Routines for Satellite object
*
* $Id: Satellite.c,v 1.21 2017/01/02 06:11:32 lloydwood Exp $
*/
#include <string.h>
#include "constants.h"
#include "orbit_utils.h"
#include "stdlib.h"
#include "Satellite.h"
/*
* satellite_create
*
* Pass unique id for new satellite plus orbital elements.
* Returns a Satellite object (which has been positioned at t=0).
*/
Satellite satellite_create(int id, OrbitalElements * poe, CentralBody * pcb)
{
Satellite s = (Satellite) calloc(1, sizeof(struct satellite));
s->id = id;
s->oe = *poe;
s->tag = FALSE;
s->gs_into_view = 0;
s->can_display_satellite = 1;
s->can_display_orbit = 1;
s->can_display_coverage = 1;
/* set name to default blank */
s->name[0] = 0;
/* give it a valid position; choose time 0 */
satellite_compute_position(s, 0.0, pcb);
/* precompute some quantities */
satellite_oe_edited(s, pcb);
return s;
}
/*
* satellite_name
*
* Set name string on satellite, using unique id assigned by _create.
*/
int satellite_name(Satellite s, char * name)
{
unsigned int n;
if (!name) return FALSE;
n = strlen(name);
if (n < SATELLITE_NAME_LENGTH) {
strcpy((char *)&s->name, name);
} else {
error("satellite name too long. Ignored.");
}
return TRUE;
}
/*
* satellite_oe_edited
*
* Call this after time 0 orbital elements (s->oe) have been changed.
* It updates some precomputed quantities.
*/
void
satellite_oe_edited(Satellite s, CentralBody * pcb)
{
/* determine classical (Keplerian) period */
s->period = oe_to_period(&(s->oe), pcb);
}
/*
* satellite_destroy
*
* Frees memory for a Satellite object
*/
void
satellite_destroy(Satellite s)
{
free((char *) s);
}
/*
* satellite_compute_position
*
* Updates the orbital elements, cartesian and spherical coordinates
* of a satellite for time t
*/
void
satellite_compute_position(Satellite s, const double t, CentralBody * pcb)
{
oe_time_to_oe(&(s->oe_t), &(s->oe), t, pcb);
oe_to_geocentric(&(s->x_C), &(s->oe_t), pcb);
cartesian_to_spherical(&(s->x_S), &(s->x_C));
s->t = t;
spherical_to_transform(s->transform, &(s->x_S), pcb->radius);
}
/*
* satellite_set_tag
*
* Sets the tag field for the satellite
*/
void
satellite_set_tag(Satellite s, int tag)
{
s->tag = tag;
}
/*
* satellite_get_tag
*
* Returns the tag field for the satellite
*/
int
satellite_get_tag(Satellite s)
{
return s->tag;
}
/*
* constellation_new_id
*
* returns an integer identifier which is not already used in
* the specified constellation
*/
int
constellation_new_id(const Constellation * pconstellation)
{
int n = 0;
Satellite_list sl = pconstellation->satellites;
while (sl && (sl->s->id == n)) {
sl = sl->next;
n++;
}
return n;
}
/*
* constellation_add
*
* adds a satellite to a constellation, modifying
* the satellite id to be the lowest possible one
*/
int
constellation_add(Constellation * pconstellation, Satellite s)
{
int n = 0;
Satellite_list newl;
Satellite_list *psl = &(pconstellation->satellites);
/* find id and empty position number */
while (*psl && ((*psl)->s->id == n)) {
psl = &((*psl)->next);
n++;
}
/* set id on satellite */
s->id = n;
/* add to satellite list */
newl = (Satellite_list) calloc(1, sizeof(struct satellite_list));
newl->s = s;
newl->next = *psl;
(*psl) = newl;
/* increment counters */
(pconstellation->n_sats)++;
if (s->can_display_satellite)
(pconstellation->n_view_sats)++;
if (s->tag)
(pconstellation->n_tag_sats)++;
return n;
}
/*
* constellation_search(Constellation *pconstellation, int id)
*
* Returns the satellite with a specified id, else NULL.
*
*/
Satellite constellation_search(const Constellation * pconstellation, int id)
{
Satellite_list sl = pconstellation->satellites;
while (sl && (id != sl->s->id))
sl = sl->next;
return (sl ? sl->s : NULL);
}
/*
* constellation_compute_positions
*
* Computes the spherical coordinates position of each satellite in the constellation
* for some specified time t.
*/
void
constellation_compute_positions(Constellation * pconstellation, double t)
{
Satellite_list sl = pconstellation->satellites;
while (sl) {
satellite_compute_position(sl->s, t, pconstellation->pcb);
sl = sl->next;
}
}
/*
* constellation_destroy_element
*
* Removes a satellite from a constellation based on its id
* and destroys it.
*/
void
constellation_destroy_element(Constellation * pconstellation, int id)
{
Satellite_list *slp = &(pconstellation->satellites);
Satellite_list old = NULL;
while (*slp && ((*slp)->s->id != id))
slp = &((*slp)->next);
if (*slp) {
/* remove from list */
old = *slp;
*slp = old->next;
/* decrement counters */
(pconstellation->n_sats)--;
if (old->s->tag)
(pconstellation->n_tag_sats)--;
if (old->s->can_display_satellite)
(pconstellation->n_view_sats)--;
/* release memory */
satellite_destroy(old->s);
free((char *) old);
}
}
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