#include <Adafruit_NeoPixel.h>

#define STRIP_PIN 2
#define NUM_PIXELS 8

Adafruit_NeoPixel strip(NUM_PIXELS, STRIP_PIN, NEO_GRB + NEO_KHZ800);

uint8_t brightness = 0;
int8_t direction = 1;

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

void loop() {
  brightness += direction * 3;
  if (brightness >= 255 || brightness <= 0) {
    direction = -direction;
    brightness = constrain(brightness, 0, 255);
  }

  for (int i = 0; i < NUM_PIXELS; i++) {
    // Offset each pixel's brightness for a wave effect
    uint8_t b = (brightness + i * 18) % 255;
    strip.setPixelColor(i, strip.Color(b, 0, b / 4));
  }
  strip.show();
  delay(30);
}