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Diffstat (limited to 'src/libred.h')
| -rw-r--r-- | src/libred.h | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/src/libred.h b/src/libred.h new file mode 100644 index 0000000..615ed04 --- /dev/null +++ b/src/libred.h @@ -0,0 +1,164 @@ +/** + * Copyright © 2016 Mattias Andrée <maandree@member.fsf.org> + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ +#ifndef LIBRED_H +#define LIBRED_H + + + +/** + * Approximate apparent size of the Sun in degrees. + */ +#define LIBRED_SOLAR_APPARENT_RADIUS (32.0 / 60.0) + + +/** + * The Sun's elevation at sunset and sunrise, measured in degrees. + */ +#define LIBRED_SOLAR_ELEVATION_SUNSET_SUNRISE (0.0) + +/** + * The Sun's elevation at civil dusk and civil dawn, measured in degrees. + */ +#define LIBRED_SOLAR_ELEVATION_CIVIL_DUSK_DAWN (-6.0) + +/** + * The Sun's elevation at nautical dusk and nautical dawn, measured in degrees. + */ +#define LIBRED_SOLAR_ELEVATION_NAUTICAL_DUSK_DAWN (-12.0) + +/** + * The Sun's elevation at astronomical dusk and astronomical dawn, measured in degrees. + */ +#define LIBRED_SOLAR_ELEVATION_ASTRONOMICAL_DUSK_DAWN (-18.0) + + +/** + * Test whether it is twilight. + * + * @param ELEV:double The current elevation. + * @return 1 if is twilight, 0 otherwise. + */ +#define LIBRED_IS_TWILIGHT(ELEV) ((-18.0 <= (ELEV)) && ((ELEV) <= 0.0)) + +/** + * Test whether it is civil twilight. + * + * @param ELEV:double The current elevation. + * @return 1 if is civil twilight, 0 otherwise. + */ +#define LIBRED_IS_CIVIL_TWILIGHT(ELEV) ((-6.0 <= (ELEV)) && ((ELEV) <= 0.0)) + +/** + * Test whether it is nautical twilight. + * + * @param ELEV:double The current elevation. + * @return 1 if is nautical twilight, 0 otherwise. + */ +#define LIBRED_IS_NAUTICAL_TWILIGHT(ELEV) ((-12.0 <= (ELEV)) && ((ELEV) <= -6.0)) + +/** + * Test whether it is astronomical twilight. + * + * @param ELEV:double The current elevation. + * @return 1 if is astronomical twilight, 0 otherwise. + */ +#define LIBRED_IS_ASTRONOMICAL_TWILIGHT(ELEV) ((-18.0 <= (ELEV)) && ((ELEV) <= -12.0)) + + + +/** + * Calculates the Sun's elevation as apparent. + * from a geographical position. + * + * @param latitude The latitude in degrees northwards from + * the equator, negative for southwards. + * @param longitude The longitude in degrees eastwards from + * Greenwich, negative for westwards. + * @return The Sun's apparent elevation as seen, right now, + * from the specified position, measured in degrees. + * + * @throws 0 On success. + * @throws Any error specified for clock_gettime(3) on error. + */ +double libred_solar_elevation(double latitude, double longitude); + + +/** + * Exit if time the is before year 0 in J2000. + * + * @return 0 on success, -1 on error. + */ +#if defined(TIMETRAVELLER) +int libred_check_timetravel(void); +#else +# define libred_check_timetravel() 0 +#endif + + + +/** + * The highest colour temperature in the table. + */ +#define LIBRED_HIGHEST_TEMPERATURE 40000 + +/** + * The lowest colour temperature in the table. + */ +#define LIBRED_LOWEST_TEMPERATURE 1000 + +/** + * The temperature difference between the colours in the table. + */ +#define LIBRED_DELTA_TEMPERATURE 100 + + + +/** + * This function must be called, once, + * before calling `libred_get_colour`. + * + * @return 0 on success, -1 on error. + * + * @throws Any error specified for `open(3)`. + */ +int libred_init_colour(void); + +/** + * Call this when the process will not + * longer make calls to `libred_get_colour`. + */ +void libred_term_colour(void); + +/** + * Get the [0, 1] sRGB values of a colour temperature. + * + * @param temp The desired colour temperature. + * @param r Output parameter for the “red” value. + * @param g Output parameter for the green value. + * @param b Output parameter for the blue value. + * @return 0 on succeess, -1 on error. + * + * @throws 0 The file did not have the expected size. + * @throws EDOM The selected temperature is below 1000 K. + * @throws Any error specified for pread(3). + */ +int libred_get_colour(long int temp, double *r, double *g, double *b); + + + +#endif + |