Arduino NeoPixels Animation without using Delay

gistfile1.txt

#include <Adafruit_NeoPixel.h>

#define NUM_PIXELS 60
unsigned long interval=50;  // the time we need to wait
unsigned long previousMillis=0;

uint32_t currentColor;// current Color in case we need it
uint16_t currentPixel = 0;// what pixel are we operating on



Adafruit_NeoPixel strip = Adafruit_NeoPixel(NUM_PIXELS, 6, NEO_GRB + NEO_KHZ800);

void setup() {
  currentColor = strip.Color(255,0,0);
  currentPixel = 0;
  strip.begin();
  strip.show(); // Initialize all pixels to 'off'
}

// Basic idea. You could reorg and pass pixel index and color as a function - or you could go through a gradient of colors.
void loop(){
if ((unsigned long)(millis() - previousMillis) >= interval) {
  previousMillis = millis();
  colorWipe();
 }
}


void colorWipe(){
  strip.setPixelColor(currentPixel,currentColor);
  strip.show();
  currentPixel++;
  if(currentPixel == NUM_PIXELS){
    currentPixel = 0;
}

An excellent example. How to use this example to smooth off the LEDs?