nwmedia-c262-lab3-hsl.ino

#define BAUD_RATE 9600
#define DELIMITER '\n'

#define LED_RED 9
#define LED_GREEN 10
#define LED_BLUE 11

#define POT_H A2
#define POT_S A1
#define POT_L A0

#define S(o, n) \
  rgb[t[int(hsl[0]) / 60 * 3 + o] + o - 2] = (n + hsl[2] - c / 2) * 255;

const int t[] = {2, 2, 2, 3, 1, 2, 3, 3, 0, 4, 2, 0, 4, 1, 1, 2, 3, 1};
float hsl[3];
uint8_t rgb[3];

void setup() {
  pinMode(LED_RED, OUTPUT);
  pinMode(LED_GREEN, OUTPUT);
  pinMode(LED_BLUE, OUTPUT);
  Serial.begin(BAUD_RATE);
}

void loop() {
  hsl[0] = (1023 - analogRead(POT_H)) * 359.99f / 1023.0f;
  hsl[1] = (1023 - analogRead(POT_S)) / 1023.0f;
  hsl[2] = (1023 - analogRead(POT_L)) / 1023.0f;

  // From https://codegolf.stackexchange.com/a/150282
  float g = 2 * hsl[2] - 1;
  float c = (g < 0 ? 1 + g : 1 - g) * hsl[1];
  float a = uint8_t(hsl[0]) % 120 / 60.f - 1;
  rgb[0] = S(0, c);
  rgb[1] = S(1, c * (a < 0 ? 1 + a : 1 - a));
  rgb[2] = S(2, 0);

  analogWrite(LED_RED, rgb[0]);
  analogWrite(LED_GREEN, rgb[1]);
  analogWrite(LED_BLUE, rgb[2]);
  delay(50);
}