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libred.h
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libred.h
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/* 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
* @param elevation Output parameter for the Sun's apparent elevation
* as seen, right now, from the specified position,
* measured in degrees
* @return 0 on success, -1 on failure
* @throws Any error specified for clock_gettime(3) on error
*/
double libred_solar_elevation(double, 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
/**
* Get the [0, 1] sRGB values of a colour temperature
*
* libred has a table of colour temperature values, this
* function interpolates values that are missing. If you
* don't want any interpolation the `temp` parameter can
* be specified in one of the following ways:
*
* - floor:
* (temp - LIBRED_LOWEST_TEMPERATURE) /
* LIBRED_DELTA_TEMPERATURE *
* LIBRED_DELTA_TEMPERATURE +
* LIBRED_LOWEST_TEMPERATURE
*
* - ceiling:
* (temp - LIBRED_LOWEST_TEMPERATURE +
* LIBRED_DELTA_TEMPERATURE - 1) /
* LIBRED_DELTA_TEMPERATURE *
* LIBRED_DELTA_TEMPERATURE +
* LIBRED_LOWEST_TEMPERATURE
*
* - round to nearest:
* (temp - LIBRED_LOWEST_TEMPERATURE +
* LIBRED_DELTA_TEMPERATURE / 2) /
* LIBRED_DELTA_TEMPERATURE *
* LIBRED_DELTA_TEMPERATURE +
* LIBRED_LOWEST_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 EDOM The selected temperature is below 1000K
*/
int libred_get_colour(long int, double *, double *, double *);
#endif