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author | Tavian Barnes <tavianator@tavianator.com> | 2014-03-11 20:20:07 -0400 |
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committer | Tavian Barnes <tavianator@tavianator.com> | 2014-03-11 20:20:39 -0400 |
commit | fd5651a159da880b0c378ae9d2a2b4ac1c0614b3 (patch) | |
tree | be73e0434fa425161fa4d95b3fad304453147247 /color.c | |
parent | d7391436ff96ff51e2417dc7edcf13ccb8300c30 (diff) | |
download | kd-forest-fd5651a159da880b0c378ae9d2a2b4ac1c0614b3.tar.xz |
Refactor hue comparator into color.c.
Diffstat (limited to 'color.c')
-rw-r--r-- | color.c | 22 |
1 files changed, 22 insertions, 0 deletions
@@ -11,6 +11,7 @@ #include "color.h" #include <math.h> +#define PI 3.1415926535897932 void color_unpack(uint8_t pixel[3], uint32_t color) @@ -117,3 +118,24 @@ color_set_Luv(double coords[3], uint32_t color) coords[1] = 13.0*coords[0]*(uprime - unprime); coords[2] = 13.0*coords[0]*(vprime - vnprime); } + +static double +hue(uint32_t color) +{ + double RGB[3]; + color_set_RGB(RGB, color); + + double hue = atan2(sqrt(3.0)*(RGB[1] - RGB[2]), 2*RGB[0] - RGB[1] - RGB[2]); + if (hue < 0.0) { + hue += 2.0*PI; + } + return hue; +} + +int +color_comparator(const void *a, const void *b) +{ + double ahue = hue(*(uint32_t *)a); + double bhue = hue(*(uint32_t *)b); + return (ahue > bhue) - (ahue < bhue); +} |