split out from radharc

Signed-off-by: Mattias Andrée <maandree@member.fsf.org>

1 files changed, 96 insertions, 0 deletions

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;
+}
+