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Diffstat (limited to 'libred.h')
| -rw-r--r-- | libred.h | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/libred.h b/libred.h new file mode 100644 index 0000000..041a49e --- /dev/null +++ b/libred.h @@ -0,0 +1,222 @@ +/* See LICENSE file for copyright and license details. */ +#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 (-32.0 / 60.0) + +/** + * 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) + +/** + * The Sun's elevation at amateur astronomical dusk and amateur astronomical dawn, measured in degrees. + */ +#define LIBRED_SOLAR_ELEVATION_AMATEUR_ASTRONOMICAL_DUSK_DAWN (-15.0) + +/** + * The Sun's lowest elevation during the golden hour, measured in degrees. + */ +#define LIBRED_SOLAR_ELEVATION_GOLDEN_HOUR_LOW (-4.0) + +/** + * The Sun's highest elevation during the golden hour, measured in degrees. + */ +#define LIBRED_SOLAR_ELEVATION_GOLDEN_HOUR_HIGH (6.0) + +/** + * The Sun's lowest elevation during the blue hour, measured in degrees. + */ +#define LIBRED_SOLAR_ELEVATION_BLUE_HOUR_LOW (-6.0) + +/** + * The Sun's highest elevation during the blue hour, measured in degrees. + */ +#define LIBRED_SOLAR_ELEVATION_BLUE_HOUR_HIGH (-4.0) + + +/** + * 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) <= -32.0 / 60.0)) + +/** + * 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) <= -32.0 / 60.0)) + +/** + * 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) <= -32.0 / 60.0)) + +/** + * 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) <= -32.0 / 60.0)) + +/** + * Test whether it is amateur astronomical twilight. + * + * @param ELEV:double The current elevation. + * @return 1 if is amatuer astronomical twilight, 0 otherwise. + */ +#define LIBRED_IS_AMATEUR_ASTRONOMICAL_TWILIGHT(ELEV) ((-18.0 <= (ELEV)) && ((ELEV) <= -15.0)) + +/** + * Test whether it is nighttime. + * + * @param ELEV:double The current elevation. + * @return 1 if is nighttime, 0 otherwise. + */ +#define LIBRED_IS_NIGHTTIME(ELEV) ((ELEV) < -18.0) + +/** + * Test whether it is daytime. + * + * @param ELEV:double The current elevation. + * @return 1 if is daytime, 0 otherwise. + */ +#define LIBRED_IS_DAYTIME(ELEV) ((ELEV) > -32.0 / 60.0) + +/** + * Test whether it is the golden hour. + * + * @param ELEV:double The current elevation. + * @return 1 if is golden hour, 0 otherwise. + */ +#define LIBRED_IS_GOLDEN_HOUR(ELEV) ((-4.0 <= (ELEV)) && ((ELEV) <= 6.0)) + +/** + * Test whether it is the blue hour. + * + * @param ELEV:double The current elevation. + * @return 1 if is blue hour, 0 otherwise. + */ +#define LIBRED_IS_BLUE_HOUR(ELEV) ((-6.0 <= (ELEV)) && ((ELEV) <= -4.0)) + + +/** + * 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, double); + + +/** + * Exit if time the is before year 0 in J2000. + * + * @return 0 on success, -1 on error. + */ +int libred_check_timetravel(void); + + + +/** + * 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. + * Note, `libred_get_colour` will make interpolation for colours + * that are not in the table. + */ +#define LIBRED_DELTA_TEMPERATURE 100 + + +/** + * The file descriptor to the colour lookup table. + * -1 if none is open. + */ +extern int libred_fd; + +/** + * Iff this macro is define `libred_fd` is available. + */ +#define LIBRED_HAVE_FD 1 + + +/** + * 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 EOVERFLOW 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, double*, double*, double*); + + + +#endif + |