/**
* 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 "libred.h"
#include "macros.h"
#include <math.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;
}
