NeoPixel Ripple

#include <Adafruit_NeoPixel.h>

#define PIN 2
#define Pixels 24
#define BG 1

// Parameter 1 = number of pixels in strip
// Parameter 2 = Arduino 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(Pixels, PIN, NEO_GRB + NEO_KHZ800);

// IMPORTANT: To reduce NeoPixel burnout risk, add 1000 uF capacitor across
// pixel power leads, add 300 - 500 Ohm resistor on first pixel's data input
// and minimize distance between Arduino and first pixel.  Avoid connecting
// on a live circuit...if you must, connect GND first.

int color;
int center = 0;
int step = -1;
int maxSteps = 16;
float fadeRate = 0.6;
int diff;

//background color
uint32_t currentBg = random(256);
uint32_t nextBg = currentBg;

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

void loop () {
  ripple();
}

void ripple() {
  if (BG){
    if (currentBg == nextBg) {
      nextBg = random(256);
    } 
    else if (nextBg > currentBg) {
      currentBg++;
    } else {
      currentBg--;
    }
    for(uint16_t l = 0; l < Pixels; l++) {
      strip.setPixelColor(l, Wheel(currentBg, 0.1));
    }
  } else {
    for(uint16_t l = 0; l < Pixels; l++) {
      strip.setPixelColor(l, 0, 0, 0);
    }
  }


  if (step == -1) {
    center = random(Pixels);
    color = random(256);
    step = 0;
  }



  if (step == 0) {
    strip.setPixelColor(center, Wheel(color, 1));
    step ++;
  } 
  else {
    if (step < maxSteps) {
      strip.setPixelColor(wrap(center + step), Wheel(color, pow(fadeRate, step)));
      strip.setPixelColor(wrap(center - step), Wheel(color, pow(fadeRate, step)));
      if (step > 3) {
        strip.setPixelColor(wrap(center + step - 3), Wheel(color, pow(fadeRate, step - 2)));
        strip.setPixelColor(wrap(center - step + 3), Wheel(color, pow(fadeRate, step - 2)));
      }
      step ++;
    } 
    else {
      step = -1;
    }
  }
  
  strip.show();
  delay(50);
}


int wrap(int step) {
  if(step < 0) return Pixels + step;
  if(step > Pixels - 1) return step - Pixels;
  return step;
}



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