diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/10deg | 391 | ||||
| -rw-r--r-- | src/blackbody.c | 130 | ||||
| -rw-r--r-- | src/blackbody.h | 51 | ||||
| -rw-r--r-- | src/parse_10deg.c | 96 | ||||
| -rw-r--r-- | src/solar.c | 312 | ||||
| -rw-r--r-- | src/solar.h | 107 |
6 files changed, 1087 insertions, 0 deletions
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0.2489 diff --git a/src/blackbody.c b/src/blackbody.c new file mode 100644 index 0000000..abe03a9 --- /dev/null +++ b/src/blackbody.c @@ -0,0 +1,130 @@ +/** + * 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/>. + */ +#include "blackbody.h" +#include "macros.h" +#include <math.h> +#include <errno.h> + + + +/** + * Convert from CIE xyY to [0, 1] sRGB. + * + * @param x The 'x' component. + * @param y The 'y' component. + * @param Y The 'Y' component. + * @param r Output parameter for the “red” value. + * (Seriously, sRGB red is orange, just look at it fullscreen.) + * @param g Output parameter for the green value. + * @param b Output parameter for the blue value. + */ +static void +ciexyy_to_srgb(double x, double y, double Y, double *r, double *g, double *b) +{ +#define SRGB(C) (((C) <= 0.0031308) ? (12.92 * (C)) : ((1.0 + 0.055) * pow((C), 1.0 / 2.4) - 0.055)) + double X, Z; + + /* Convert CIE xyY to CIE XYZ. */ + X = Y * (y == 0.0 ? 0.0 : (x / y)); + Z = Y * (y == 0.0 ? 0.0 : ((1.0 - x - y) / y)); + + /* Convert CIE XYZ to [0, 1] linear RGB. (ciexyz_to_linear) */ + *r = ( 3.240450 * X) + (-1.537140 * Y) + (-0.4985320 * Z); + *g = (-0.969266 * X) + ( 1.876010 * Y) + ( 0.0415561 * Z); + *b = (0.0556434 * X) + (-0.204026 * Y) + ( 1.0572300 * Z); + + /* Convert [0, 1] linear RGB to [0, 1] sRGB. */ + SRGB(*r), SRGB(*g), SRGB(*b); +} + + +/** + * Perform linear interpolation (considered very good) + * between the CIE xyY values for two colour temperatures + * and convert the result to sRGB. The two colours should + * be the closest below the desired colour temperature, + * and the closest above the desired colour temperature. + * + * @param x1 The 'x' component for the low colour. + * @param y1 The 'y' component for the low colour. + * @param x2 The 'x' component for the high colour. + * @param y2 The 'y' component for the high colour. + * @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. + */ +static void +interpolate(double x1, double y1, double x2, double y2, double temp, double *r, double *g, double *b) +{ + double weight = fmod(temp, (double)DELTA_TEMPERATURE) / (double)DELTA_TEMPERATURE; + double x = x1 * (1 - weight) + x2 * weight; + double y = y1 * (1 - weight) + y2 * weight; + ciexyy_to_srgb(x, y, 1.0, r, g, b); +} + + +/** + * Get the [0, 1] sRGB values of a colour temperature. + * + * @param fd File descriptor for the colour table. + * @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. + */ +int +get_colour(int fd, long int temp, double *r, double *g, double *b) +{ + double values[10]; /* low:x,y,r,g,b + high:x,y,r,g,b */ + off_t offset; + double max; + + /* We do not have any values for above 40 000 K, but + * the differences will be unnoticeable, perhaps even + * unencodeable. */ + if (temp > HIGHEST_TEMPERATURE) temp = HIGHEST_TEMPERATURE; + /* Things do not glow below 1000 K. Yes, fire is hot! */ + if (temp < LOWEST_TEMPERATURE) t ((errno = EDOM)); + + /* Read table. */ + offset = ((off_t)temp - LOWEST_TEMPERATURE) / DELTA_TEMPERATURE; + offset *= (off_t)(sizeof(values) / 2); + errno = 0; xpread(fd, values, sizeof(values), offset); + + /* Get colour. */ + if (temp % DELTA_TEMPERATURE) + interpolate(values[0], values[1], values[6], values[7], (double)temp, r, g, b); + else + *r = values[2], *g = values[3], *b = values[4]; + + /* Adjust colours for use. */ + max = fmax(fmax(fabs(*r), fabs(*g)), fabs(*b)); + if (max != 0) *r /= max, *g /= max, *b /= max; + *r = *r > 0.0 ? *r : 0.0; + *g = *g > 0.0 ? *g : 0.0; + *b = *b > 0.0 ? *b : 0.0; + + return 0; +fail: + return -1; +} + diff --git a/src/blackbody.h b/src/blackbody.h new file mode 100644 index 0000000..499e9b8 --- /dev/null +++ b/src/blackbody.h @@ -0,0 +1,51 @@ +/** + * 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/>. + */ + + + +/** + * 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 + + + +/** + * Get the [0, 1] sRGB values of a colour temperature. + * + * @param fd File descriptor for the colour table. + * @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. + */ +int libred_get_colour(int fd, long int temp, double *r, double *g, double *b); + diff --git a/src/parse_10deg.c b/src/parse_10deg.c new file mode 100644 index 0000000..ef1c3d5 --- /dev/null +++ b/src/parse_10deg.c @@ -0,0 +1,96 @@ +/** + * 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/>. + */ +#include "blackbody.h" +#include "macros.h" +#include <sys/stat.h> + + + +/** + * The number of measured temperatures. + */ +#define TEMPERATURES ((LIBRED_HIGHEST_TEMPERATURE - LIBRED_LOWEST_TEMPERATURE) / LIBRED_DELTA_TEMPERATURE + 1) + + + +/** + * Convert from CIE xyY to [0, 1] sRGB. + * + * This function is identical to that in 'blackbody.c'. + * + * @param x The 'x' component. + * @param y The 'y' component. + * @param Y The 'Y' component. + * @param r Output parameter for the “red” value. + * (Seriously, sRGB red is orange, just look at it fullscreen.) + * @param g Output parameter for the green value. + * @param b Output parameter for the blue value. + */ +static void ciexyy_to_srgb(double x, double y, double Y, double *r, double *g, double *b) +{ +#define SRGB(C) (((C) <= 0.0031308) ? (12.92 * (C)) : ((1.0 + 0.055) * pow((C), 1.0 / 2.4) - 0.055)) + double X, Z; + + /* Convert CIE xyY to CIE XYZ. */ + X = Y * (y == 0.0 ? 0.0 : (x / y)); + Z = Y * (y == 0.0 ? 0.0 : ((1.0 - x - y) / y)); + + /* Convert CIE XYZ to [0, 1] linear RGB. (ciexyz_to_linear) */ + *r = ( 3.240450 * X) + (-1.537140 * Y) + (-0.4985320 * Z); + *g = (-0.969266 * X) + ( 1.876010 * Y) + ( 0.0415561 * Z); + *b = (0.0556434 * X) + (-0.204026 * Y) + ( 1.0572300 * Z); + + /* Convert [0, 1] linear RGB to [0, 1] sRGB. */ + SRGB(*r), SRGB(*g), SRGB(*b); +} + + +/** + * Create the lookup table of temperatures. + * + * Standard input should be the file '10deg', + * standard output should be the table file + * and must be a regular file. + * + * @param argc Should be 1. + * @param argv Should only contain the name of the process. + * @return 0 on success, 1 on error. + */ +int main(int argc, char *argv[]) +{ +#define x (xyrgb[0]) +#define y (xyrgb[1]) +#define r (xyrgb[2]) +#define g (xyrgb[3]) +#define b (xyrgb[4]) + + double xyrgb[5]; + struct stat attr; + long int temp = LIBRED_LOWEST_TEMPERATURE; + + for (; fscanf(stdin, "%lf %lf\n", &x, &y) == 2; temp += LIBRED_DELTA_TEMPERATURE) + { + (temp == 6500) ? (r = g = b = 1.0) : ciexyy_to_srgb(x, y, 1.0, &r, &g, &b); + xwrite(STDOUT_FILENO, xyrgb, sizeof(xyrgb)); + } + xwrite(STDOUT_FILENO, xyrgb, sizeof(xyrgb)); /* sugar */ + t (fstat(STDOUT_FILENO, &attr)); + return ((size_t)(attr.st_size) != (TEMPERATURES + 1) * 5 * sizeof(double)); + fail: + return perror(argc ? *argv : "parse_10deg"), 1; +} + diff --git a/src/solar.c b/src/solar.c new file mode 100644 index 0000000..8a57507 --- /dev/null +++ b/src/solar.c @@ -0,0 +1,312 @@ +/** + * 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/>. + */ +#include <math.h> +#include <time.h> +#include <errno.h> + + + +#if !defined(CLOCK_REALTIME_COARSE) +# define CLOCK_REALTIME_COARSE CLOCK_REALTIME +#endif + + + +/** + * Get current Julian Centuries time (100 Julian days since J2000.) + * + * @return The current Julian Centuries time. + * + * @throws 0 On success. + * @throws Any error specified for clock_gettime(3) on error. + */ +static double +julian_centuries() +{ + struct timespec now; + double tm; + if (clock_gettime(CLOCK_REALTIME_COARSE, &now)) return 0.0; + tm = (double)(now.tv_nsec) / 1000000000.0 + (double)(now.tv_sec); + tm = (tm / 86400.0 + 2440587.5 - 2451545.0) / 36525.0; + return errno = 0, tm; +} + +/** + * Convert a Julian Centuries timestamp to a Julian Day timestamp. + * + * @param tm The time in Julian Centuries + * @return The time in Julian Days + */ +static inline double +julian_centuries_to_julian_day(double tm) +{ + return tm * 36525.0 + 2451545.0; +} + + +/** + * Convert an angle (or otherwise) from degrees to radians. + * + * @param deg The angle in degrees. + * @param The angle in radians. + */ +static inline double +radians(double deg) +{ + return deg * (double)M_PI / 180.0; +} + +/** + * Convert an angle (or otherwise) from radians to degrees. + * + * @param rad The angle in radians. + * @param The angle in degrees. + */ +static inline double +degrees(double rad) +{ + return rad * 180.0 / (double)M_PI; +} + + +/** + * Calculates the Sun's elevation from the solar hour angle + * + * @param longitude The longitude in degrees eastwards. + * from Greenwich, negative for westwards. + * @param declination The declination, in radians. + * @param hour_angle The solar hour angle, in radians. + * @return The Sun's elevation, in radians. + */ +static inline double +elevation_from_hour_angle(double latitude, double declination, double hour_angle) +{ + double rc = cos(radians(latitude)); + rc *= cos(hour_angle) * cos(declination); + rc += sin(radians(latitude)) * sin(declination); + return asin(rc); +} + +/** + * Calculates the Sun's geometric mean longitude. + * + * @param tm The time in Julian Centuries. + * @return The Sun's geometric mean longitude in radians. + */ +static inline double +sun_geometric_mean_longitude(double tm) +{ + double rc = fmod(pow(0.0003032 * tm, 2.0) + 36000.76983 * tm + 280.46646, 360.0); +#if defined(TIMETRAVELLER) + rc = rc < 0.0 ? (rc + 360.0) : rc; +#endif + return radians(rc); +} + +/** + * Calculates the Sun's geometric mean anomaly. + * + * @param tm The time in Julian Centuries. + * @return The Sun's geometric mean anomaly in radians. + */ +static inline double +sun_geometric_mean_anomaly(double tm) +{ + return radians(pow(-0.0001537 * tm, 2.0) + 35999.05029 * tm + 357.52911); +} + +/** + * Calculates the Earth's orbit eccentricity. + * + * @param tm The time in Julian Centuries. + * @return The Earth's orbit eccentricity. + */ +static inline double +earth_orbit_eccentricity(double tm) +{ + return pow(-0.0000001267 * tm, 2.0) - 0.000042037 * tm + 0.016708634; +} + +/** + * Calculates the Sun's equation of the centre, the difference + * between the true anomaly and the mean anomaly. + * + * @param tm The time in Julian Centuries. + * @return The Sun's equation of the centre, in radians. + */ +static inline double +sun_equation_of_centre(double tm) +{ + double a = sun_geometric_mean_anomaly(tm), rc; + rc = sin(1.0 * a) * (pow(-0.000014 * tm, 2.0) - 0.004817 * tm + 1.914602); + rc += sin(2.0 * a) * (-0.000101 * tm + 0.019993); + rc += sin(3.0 * a) * 0.000289; + return radians(rc); +} + +/** + * Calculates the Sun's real longitudinal position. + * + * @param tm The time in Julian Centuries. + * @return The longitude, in radians. + */ +static inline double +sun_real_longitude(double tm) +{ + return sun_geometric_mean_longitude(tm) + sun_equation_of_centre(tm); +} + +/** + * Calculates the Sun's apparent longitudinal position. + * + * @param tm The time in Julian Centuries. + * @return The longitude, in radians. + */ +static inline double +sun_apparent_longitude(double tm) +{ + double rc = degrees(sun_real_longitude(tm)) - 0.00569; + return radians(rc - 0.00478 * sin(radians(-1934.136 * tm + 125.04))); +} + +/** + * Calculates the mean ecliptic obliquity of the Sun's + * apparent motion without variation correction. + * + * @param tm The time in Julian Centuries. + * @return The uncorrected mean obliquity, in radians. + */ +static double +mean_ecliptic_obliquity(double tm) +{ + double rc = pow(0.001813 * tm, 3.0) - pow(0.00059 * tm, 2.0) - 46.815 * tm + 21.448; + return radians(23.0 + (26.0 + rc / 60.0) / 60.0); +} + +/** + * Calculates the mean ecliptic obliquity of the Sun's + * parent motion with variation correction. + * + * @param tm The time in Julian Centuries. + * @return The mean obliquity, in radians. + */ +static double +corrected_mean_ecliptic_obliquity(double tm) +{ + double rc = 0.00256 * cos(radians(-1934.136 * tm + 125.04)); + return radians(rc + degrees(mean_ecliptic_obliquity(tm))); +} + +/** + * Calculates the Sun's declination. + * + * @param tm The time in Julian Centuries. + * @return The Sun's declination, in radian. + */ +static inline double +solar_declination(double tm) +{ + double rc = sin(corrected_mean_ecliptic_obliquity(tm)); + return asin(rc * sin(sun_apparent_longitude(tm))); +} + +/** + * Calculates the equation of time, the discrepancy + * between apparent and mean solar time. + * + * @param tm The time in Julian Centuries. + * @return The equation of time, in degrees. + */ +static inline double +equation_of_time(double tm) +{ + double l = sun_geometric_mean_longitude(tm); + double e = earth_orbit_eccentricity(tm); + double m = sun_geometric_mean_anomaly(tm); + double y = pow(tan(corrected_mean_ecliptic_obliquity(tm) / 2.0), 2.0); + double rc = y * sin(2.0 * l); + rc += (4.0 * y * cos(2.0 * l) - 2.0) * e * sin(m); + rc -= pow(0.5 * y, 2.0) * sin(4.0 * l); + rc -= pow(1.25 * e, 2.0) * sin(2.0 * m); + return 4.0 * degrees(rc); +} + +/** + * Calculates the Sun's elevation as apparent. + * from a geographical position. + * + * @param tm The time in Julian Centuries. + * @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 at the specified time as seen + * from the specified position, measured in radians. + */ +static inline double +solar_elevation_from_time(double tm, double latitude, double longitude) +{ + double rc = julian_centuries_to_julian_day(tm); + rc = (rc - round(rc) - 0.5) * 1440; + rc = 720.0 - rc - equation_of_time(tm); + rc = radians(rc / 4.0 - longitude); + return elevation_from_hour_angle(latitude, solar_declination(tm), rc); +} + + +/** + * 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 +solar_elevation(double latitude, double longitude) +{ + double tm = julian_centuries(); + return errno ? -1 : degrees(solar_elevation_from_time(tm, latitude, longitude)); +} + + +/** + * Exit if time the is before year 0 in J2000. + * + * @return 0 on success, -1 on error. + */ +#if defined(TIMETRAVELLER) +int +check_timetravel(void) +{ + struct timespec now; + if (clock_gettime(CLOCK_REALTIME, &now)) return -1; + if (now.tv_nsec < (time_t)946728000L) + fprintf(stderr, "We have detected that you are a time-traveller" + "(or your clock is not configured correctly.)" + "Please recompile with -DTIMETRAVELLER" + "(or correct your clock.)"), exit(1); + return 0; +} +#endif + diff --git a/src/solar.h b/src/solar.h new file mode 100644 index 0000000..8e94cf9 --- /dev/null +++ b/src/solar.h @@ -0,0 +1,107 @@ +/** + * 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/>. + */ + + +/** + * 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 + |