Add hsv function

qthing/color.cpp

@@ -27,4 +27,45 @@ namespace qthing {
           return RGB(h * v, 0, (1 - h) * v);
       }
   }
+
+  RGB hsv(float hue, float saturation, float value) {
+    if(value <= 0)
+      return RGB();
+
+    if(saturation <= 0)
+      return RGB(value, value, value);
+
+    if(saturation > 1)
+      saturation = 1;
+
+    if(value > 1)
+      value = 1;
+
+    hue = fmod(hue, 1);
+    if(hue < 0)
+      ++hue;
+
+    float hh = hue * 6;
+    int i = (int)hh;
+    float ff = hh - i;
+    float p = value * (1.0 - saturation);
+    float q = value * (1.0 - (saturation * ff));
+    float t = value * (1.0 - (saturation * (1.0 - ff)));
+
+    switch(i) {
+      case(0):
+        return RGB(value, t, p);
+      case(1):
+        return RGB(q, value, p);
+      case(2):
+        return RGB(p, value, t);
+      case(3):
+        return RGB(p, q,  value);
+      case(4):
+        return RGB(t, p, value);
+      case(5):
+        return RGB(value, p, q);
+    }
+    return RGB();
+  }
 }

qthing/qthing.h

@@ -228,6 +228,7 @@ namespace qthing {
     };
 
     RGB hue(const float hue, const float value = 1);
+    RGB hsv(float hue, float staturation = 1, float value = 1);
 
     typedef std::function<led_color_t(uint8_t, uint16_t, led_color_t)> led_color_handler_t;