Companion Cube code

#include <Adafruit_NeoPixel.h>

#define PIN 0 //The data pin for the leds
#define NUMLEDS 4 //The number of leds in the strip

Adafruit_NeoPixel strip = Adafruit_NeoPixel(NUMLEDS, PIN, NEO_GRB + NEO_KHZ800);

struct  RAINBOWSTRUCT {
  unsigned  long  period;
  unsigned  long  last;
  uint16_t  value;
  uint16_t bri; //brightness value
  uint16_t bridir; //brightness direction, 0 decreasing 1 increasing, for breathing effect
  unsigned long briperiod; //brightness period
  unsigned long brilast; //last time brightness process executed
};

struct RAINBOWSTRUCT rainbow;

void setup() {
  rainbow.period=50;
  rainbow.last=0;
  rainbow.value=240;
  rainbow.bri=255;
  rainbow.bridir=0;
  rainbow.briperiod=15;
  rainbow.brilast=0;
  strip.begin();
  strip.show(); // Initialize all pixels to 'off'
}

void loop() {
unsigned long curr_ms = millis ();
loop_bri(curr_ms);
//loop_rainbow(curr_ms);
}

void loop_rainbow(unsigned long curr_ms){
  if(curr_ms - rainbow.last >= rainbow.period){
    rainbow.last=curr_ms;//new time


    for(int i=0; i<strip.numPixels(); i++) {
      strip.setPixelColor(i,Wheel(rainbow.value));
    }
    rainbow.value=(rainbow.value+1)&255;
    strip.show();
  }
}

void loop_bri(unsigned long curr_ms){
  if(curr_ms - rainbow.brilast >= rainbow.briperiod){
    rainbow.brilast=curr_ms;//new time

    if(rainbow.bridir){
      rainbow.bri=rainbow.bri+1;
    }else{
      rainbow.bri=rainbow.bri-1;
    }
    strip.setBrightness(rainbow.bri);
    for(int i=0; i<strip.numPixels(); i++) {
      strip.setPixelColor(i,Wheel(rainbow.value));
    }
    strip.show();
    if(rainbow.bri==255){
      rainbow.bridir=0;
    }

    if(rainbow.bri==30){
      rainbow.bridir=1;
    }
  }
}

// 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);
  }
  if(WheelPos < 170) {
    WheelPos -= 85;
    return strip.Color(0, WheelPos * 3, 255 - WheelPos * 3);
  }
  WheelPos -= 170;
  return strip.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
}