From fd5651a159da880b0c378ae9d2a2b4ac1c0614b3 Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@tavianator.com>
Date: Tue, 11 Mar 2014 20:20:07 -0400
Subject: Refactor hue comparator into color.c.

---
 color.c | 22 ++++++++++++++++++++++
 color.h |  4 ++++
 main.c  | 29 +----------------------------
 3 files changed, 27 insertions(+), 28 deletions(-)

diff --git a/color.c b/color.c
index 34eab01..d75d58f 100644
--- a/color.c
+++ b/color.c
@@ -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);
+}
diff --git a/color.h b/color.h
index 6ce5168..6fec82d 100644
--- a/color.h
+++ b/color.h
@@ -15,6 +15,7 @@
 #include "kd-forest.h"
 #include <stdint.h>
 
+// Unpack a color into 8-bit RGB values
 void color_unpack(uint8_t pixel[3], uint32_t color);
 
 // Use RGB coordinates
@@ -24,4 +25,7 @@ void color_set_Lab(double coords[3], uint32_t color);
 // Use CIE L*u*v* coordinates
 void color_set_Luv(double coords[3], uint32_t color);
 
+// For sorting by hue
+int color_comparator(const void *a, const void *b);
+
 #endif // COLOR_H
diff --git a/main.c b/main.c
index d2f3871..e186bc8 100644
--- a/main.c
+++ b/main.c
@@ -109,33 +109,6 @@ remove_non_boundary(kd_forest_t *kdf, kd_node_t *node, unsigned int width, unsig
   }
 }
 
-#if HUE_SORT
-#define PI 3.1415926535897932
-
-static double
-hue(uint32_t color)
-{
-  int R = (color >> 16) & 0xFF;
-  int G = (color >> 8) & 0xFF;
-  int B = color & 0xFF;
-
-  double hue = atan2(sqrt(3.0)*(G - B), 2*R - G - B);
-  if (hue < 0.0) {
-    hue += 2.0*PI;
-  }
-  return hue;
-}
-
-static int
-hue_comparator(const void *a, const void *b)
-{
-  double ahue = hue(*(uint32_t *)a);
-  double bhue = hue(*(uint32_t *)b);
-  return (ahue > bhue) - (ahue < bhue);
-}
-
-#endif
-
 int
 main(void)
 {
@@ -166,7 +139,7 @@ main(void)
   }
 #endif
 #if HUE_SORT
-  qsort(colors, size, sizeof(uint32_t), hue_comparator);
+  qsort(colors, size, sizeof(uint32_t), color_comparator);
 #endif
 
   // Make the actual bitmap image
-- 
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