Function to convert a color to its Red, Green, and Blue components

hueToRGB.c

// Courtesy http://www.instructables.com/id/How-to-Use-an-RGB-LED/?ALLSTEPS
// function to convert a color to its Red, Green, and Blue components.

void hueToRGB(uint8_t hue, uint8_t brightness, bool invert) {
  uint16_t scaledHue = (hue * 6);
  uint8_t segment = scaledHue / 256; // segment 0 to 5 around the
                                     // color wheel
  uint16_t segmentOffset =
    scaledHue - (segment * 256); // position within the segment

  uint8_t complement = 0;
  uint16_t prev = (brightness * ( 255 -  segmentOffset)) / 256;
  uint16_t next = (brightness *  segmentOffset) / 256;

  if(invert) {
    brightness = 255 - brightness;
    complement = 255;
    prev = 255 - prev;
    next = 255 - next;
  }

  switch(segment ) {
  case 0:      // red
    R = brightness;
    G = next;
    B = complement;
    break;
  case 1:     // yellow
    R = prev;
    G = brightness;
    B = complement;
    break;
  case 2:     // green
    R = complement;
    G = brightness;
    B = next;
    break;
  case 3:    // cyan
    R = complement;
    G = prev;
    B = brightness;
    break;
  case 4:    // blue
    R = next;
    G = complement;
    B = brightness;
    break;
  case 5:      // magenta
  default:
    R = brightness;
    G = complement;
    B = prev;
    break;
  }
}