/*  
  Neopixel Colour Wheel

  Aug 18 2024
  Version 001
  by trulyBent, Public Domain

  I don't know how this Neopixel wheel was built, but I found it 
  here: https://wokwi.com/projects/406466798528780289?gh=1
  I had to rewrite the code, including finding the wheel() function
  (https://forum.arduino.cc/t/wheel-was-not-declared-in-scope/478906/10)

*/

#include <Adafruit_NeoPixel.h>
int PIN = 12;
int N_LEDS = 40;
Adafruit_NeoPixel strip = Adafruit_NeoPixel(N_LEDS, PIN);

////////////////////////////////////////////////////////////
// Input a value 0 to 255 to get a color value.
// The colours are a transition r - g - b - back to r.
uint32_t wheel(byte WheelPos) {
  WheelPos = 255 - WheelPos;
  if (WheelPos < 85) {
    return strip.Color(255 - WheelPos * 3, 0, WheelPos * 3);
  } else if (WheelPos < 170) {
    WheelPos -= 85;
    return strip.Color(0, WheelPos * 3, 255 - WheelPos * 3);
  } else {
    WheelPos -= 170;
    return strip.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
  }
}

////////////////////////////////////////////////////////////
void setup() {
  strip.begin();
}

////////////////////////////////////////////////////////////
void loop() {
  uint16_t i, j;

  for (j = 0; j < 256; j++) {
    for (i = 0; i < strip.numPixels(); i++) {
      strip.setPixelColor(i, wheel((i + j) & 255));
    }
    strip.show();
    delay(100);
  }
}