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/* redshift.c */
/* Copyright (c) 2009, Jon Lund Steffensen <jonlst@gmail.com> */
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <locale.h>
#include "solar.h"
#include "colortemp.h"
#define MIN_LAT -90.0
#define MAX_LAT 90.0
#define MIN_LON -180.0
#define MAX_LON 180.0
#define MIN_TEMP 1000
#define MAX_TEMP 10000
#define USAGE \
"Usage: %s LAT LON DAY-TEMP NIGHT-TEMP [GAMMA]\n"
#define DEG_CHAR 0xb0
static void
printtime(time_t time)
{
char s[64];
strftime(s, 64, "%a, %d %b %Y %H:%M:%S %z", localtime(&time));
printf("%s\n", s);
}
int
main(int argc, char *argv[])
{
/* Check extensions needed for color temperature adjustment. */
int r = colortemp_check_extension();
if (r < 0) {
fprintf(stderr, "Unable to set color temperature.\n");
exit(EXIT_FAILURE);
}
/* Init locale for special symbols */
char *loc = setlocale(LC_CTYPE, "");
if (loc == NULL) {
fprintf(stderr, "Unable to set locale.\n");
exit(EXIT_FAILURE);
}
/* Load arguments */
if (argc < 5) {
printf(USAGE, argv[0]);
exit(EXIT_FAILURE);
}
/* Latitude */
float lat = atof(argv[1]);
if (lat < MIN_LAT || lat > MAX_LAT) {
fprintf(stderr,
"Latitude must be between %.1f%lc and %.1f%lc\n",
MIN_LAT, DEG_CHAR, MAX_LAT, DEG_CHAR);
exit(EXIT_FAILURE);
}
/* Longitude */
float lon = atof(argv[2]);
if (lon < MIN_LON || lon > MAX_LON) {
fprintf(stderr,
"Longitude must be between %.1f%lc and %.1f%lc\n",
MIN_LON, DEG_CHAR, MAX_LON, DEG_CHAR);
exit(EXIT_FAILURE);
}
/* Color temperature at daytime */
int temp_day = atoi(argv[3]);
if (temp_day < MIN_TEMP || temp_day >= MAX_TEMP) {
fprintf(stderr, "Temperature must be between %uK and %uK\n",
MIN_TEMP, MAX_TEMP);
exit(EXIT_FAILURE);
}
/* Color temperature at night */
int temp_night = atoi(argv[4]);
if (temp_night < MIN_TEMP || temp_night >= MAX_TEMP) {
fprintf(stderr, "Temperature must be between %uK and %uK\n",
MIN_TEMP, MAX_TEMP);
exit(EXIT_FAILURE);
}
/* Gamma value */
float gamma = 1.0;
if (argc > 5) gamma = atof(argv[5]);
/* Current angular elevation of the sun */
time_t now = time(NULL);
double elevation = solar_elevation(now, lat, lon);
printf("Solar elevation is %f\n", elevation);
/* Use elevation of sun to set color temperature */
int temp = 0;
if (elevation < SOLAR_CIVIL_TWILIGHT_ELEV) {
temp = temp_night;
printf("Set color temperature to %uK\n", temp_night);
} else if (elevation < SOLAR_DAYTIME_ELEV) {
float a = (SOLAR_DAYTIME_ELEV - elevation) /
(SOLAR_DAYTIME_ELEV - SOLAR_CIVIL_TWILIGHT_ELEV);
temp = (1.0-a)*temp_day + a*temp_night;
printf("Interpolated (%f) temperature is %uK\n", a, temp);
} else {
temp = temp_day;
printf("Set color temperature to %uK\n", temp_day);
}
/* Set color temperature */
r = colortemp_set_temperature(temp, gamma);
if (r < 0) {
fprintf(stderr, "Unable to set color temperature.\n");
exit(EXIT_FAILURE);
}
return EXIT_SUCCESS;
}
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