/**********************************************
*** An attempt to change my animations from ***
***  delay to millis, allowing a momentary  ***
***  push button to interrupt sequence and  ***
***      cycle through animation list.      ***
**********************************************/

#include <FastLED.h>       // included libraries make

#define VOLTS           5  // max power
#define PWR_LIMIT     500  // 500mA max current
#define LED_PIN         7  // data pin
#define NUM_LEDS       45  // total number of pixels
#define BRIGHTNESS     50  // set brightness level

 CRGB leds [NUM_LEDS];     // initialize all pixels

uint8_t state = 0;
uint8_t i = 0;
unsigned long currentMillis;
unsigned long changeTime;

void setup()
{
  FastLED.addLeds<WS2812B,LED_PIN,GRB>(leds, NUM_LEDS).setCorrection(TypicalLEDStrip);
  FastLED.setMaxPowerInVoltsAndMilliamps( VOLTS, PWR_LIMIT);

  delay(2000); // short delay for recovery
  FastLED.setBrightness(BRIGHTNESS);
  FastLED.clear();
  FastLED.show();
}

void loop()
{
  currentMillis = millis();

  if (currentMillis - changeTime > 50)
  {
    changeTime = currentMillis;
    updateLEDs();
  }

  // Do other stuff here... like check buttons.
}

void updateLEDs()
{
  switch (state)
  {
    case 0:
      leds[i++] = CRGB::Yellow;
      FastLED.show();
      if (i == 45)
      {
        state++;
        i = 0;
      }
      break;

    case 1:
      i++;
      if (i == 20)
      {
        state++;
        i = 0;
      }
      break;

    case 2:
      leds[i++] = CRGB::Black;
      FastLED.show();

      if (i == 45)
      {
        state++;
        i = 0;
      }
      break;

    case 3:
      i++;
      if (i == 20)
      {
        state = 0;
        i = 0;
      }

    default:
      break;
  }
}