#include <Adafruit_NeoPixel.h>

#include <Adafruit_NeoPixel.h>

#define PIN 7
#define NUM_LEDS 16

Adafruit_NeoPixel strip = Adafruit_NeoPixel(NUM_LEDS, PIN, NEO_GRB + NEO_KHZ800);
// Adafruit_NeoPixel strip = Adafruit_NeoPixel(60, PIN, NEO_RGBW + NEO_KHZ800);

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

int32_t g = 0;

// Gets the intensity for LED `l`.
// s is a step between 0 and 1000.
// l is the led number, between 0 and NUM_LEDS.
float grad(int s, int l, float num_pixels) {
  float scaled = s * 16.0 / 1000;
  float distance = abs(scaled - l);
  float val = 1 - (2/num_pixels) * distance;
  return max(0, val);
}

void loop() {
  float num_pixels = 2.8;
  for (int i = 0; i < 1000; i++) {
    for (int pixel = 0; pixel < 16; pixel++) {
      // strip.setPixelColor(pixel, 0, 5, 50);
      strip.setPixelColor(pixel, strip.Color(0, 0, grad(i, pixel, num_pixels) * 255));
    }
    strip.show();
    delay(1);
  }
}