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ef12121621
Defined data structure astro_local_solar_eclipse_t. Created stubs for functions to find local solar eclipses. Renamed lunar eclipse 'center' to 'peak' to be consistent.
88 lines
2.2 KiB
C
88 lines
2.2 KiB
C
/*
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lunar_eclipse.c - by Don Cross - 2020-05-17
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Example C program for Astronomy Engine:
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https://github.com/cosinekitty/astronomy
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Searches for the next 10 partial/total lunar eclipses after
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the current date, or a date specified on the command line.
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*/
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#include <stdio.h>
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#include "astro_demo_common.h"
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void PrintEclipse(astro_lunar_eclipse_t eclipse)
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{
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/*
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Calculate beginning/ending of different phases
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of an eclipse by subtracting/adding the peak time
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with the number of minutes indicated by the "semi-duration"
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fields sd_partial and sd_total.
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*/
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const double MINUTES_PER_DAY = 24 * 60;
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PrintTime(Astronomy_AddDays(eclipse.peak, -eclipse.sd_partial / MINUTES_PER_DAY));
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printf(" - Partial eclipse begins.\n");
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if (eclipse.sd_total > 0.0)
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{
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PrintTime(Astronomy_AddDays(eclipse.peak, -eclipse.sd_total / MINUTES_PER_DAY));
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printf(" - Total eclipse begins.\n");
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}
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PrintTime(eclipse.peak);
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printf(" - Peak of %s eclipse.\n", (eclipse.kind == ECLIPSE_TOTAL) ? "total" : "partial");
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if (eclipse.sd_total > 0.0)
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{
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PrintTime(Astronomy_AddDays(eclipse.peak, +eclipse.sd_total / MINUTES_PER_DAY));
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printf(" - Total eclipse ends.\n");
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}
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PrintTime(Astronomy_AddDays(eclipse.peak, +eclipse.sd_partial / MINUTES_PER_DAY));
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printf(" - Partial eclipse ends.\n\n");
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}
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int main(int argc, const char *argv[])
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{
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astro_time_t time;
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int count;
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astro_lunar_eclipse_t eclipse;
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switch (argc)
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{
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case 1:
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time = Astronomy_CurrentTime();
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break;
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case 2:
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if (ParseTime(argv[1], &time))
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return 1;
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break;
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default:
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fprintf(stderr, "USAGE: lunar_eclipse [date]\n");
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return 1;
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}
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eclipse = Astronomy_SearchLunarEclipse(time);
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count = 0;
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for(;;)
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{
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if (eclipse.status != ASTRO_SUCCESS)
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{
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fprintf(stderr, "Error %d: could not find next lunar eclipse.\n", eclipse.status);
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return 1;
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}
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if (eclipse.kind != ECLIPSE_PENUMBRAL)
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{
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PrintEclipse(eclipse);
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if (++count == 10)
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return 0;
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}
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eclipse = Astronomy_NextLunarEclipse(eclipse.peak);
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}
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}
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