#include <Adafruit_NeoPixel.h>
#define PIN 6
#define NUM_LEDS 16
// Parameter 1 = number of pixels in strip
// Parameter 2 = pin number (most are valid)
// Parameter 3 = pixel type flags, add together as needed:
//   NEO_KHZ800  800 KHz bitstream (most NeoPixel products w/WS2812 LEDs)
//   NEO_KHZ400  400 KHz (classic 'v1' (not v2) FLORA pixels, WS2811 drivers)
//   NEO_GRB     Pixels are wired for GRB bitstream (most NeoPixel products)
//   NEO_RGB     Pixels are wired for RGB bitstream (v1 FLORA pixels, not v2)
Adafruit_NeoPixel strip = Adafruit_NeoPixel(NUM_LEDS, PIN, NEO_GRB + NEO_KHZ800);

int first = 0;
int len = 7;
uint8_t bright[NUM_LEDS];

void setup() {
  strip.begin();
  strip.show(); // Initialize all pixels to 'off'

  for (int i = 0; i< NUM_LEDS; i++)
    bright[i]=0;

// initialise the stirp here

  for (int i = first; i< len; i++)
    bright[i]=255;
  bright[len-1]=255/2;
  bright[first]=255/2;

}


void loop() {

  //strip.clear(); // Set all pixel colors to 'off'

  for (int led = 0; led< NUM_LEDS; led++)
  {
      if (led>=first and led<first+len)
      {
        if (led == first+len-2)
        {
          if (bright[led]<255)
            bright[led]++;
            if (first+len-1<NUM_LEDS) bright[led+1]++;
            else bright[led-NUM_LEDS+1]++;
        }
        if (led == first)
        {
          bright[first]--;
          if (first+len-1<NUM_LEDS) bright[first+1]--;
          else bright[first-NUM_LEDS+1]--;
        }
      }
  }

  if (bright[first]==0)
  {
    first = (first + 1)%NUM_LEDS;
  }

  for (int led = 0; led< NUM_LEDS; led++)
    strip.setPixelColor(led, bright[led], bright[led], bright[led]);

  strip.show();

  delay(10);
}