#include "FastLED.h"

#define DATA_PIN 2
#define BRIGHTNESS 255
#define NUM_LEDS 256
#define LED_TYPE    WS2812B
#define COLOR_ORDER GRB
// Define the array of leds
CRGB leds[NUM_LEDS];

uint8_t LED_COLS = 16;
uint8_t LED_ROWS = 16;
const bool    kMatrixSerpentineLayout = true;
int offset = 0;


void setup() {
  // put your setup code here, to run once:
  delay(1000); 

  FastLED.addLeds<LED_TYPE,DATA_PIN,COLOR_ORDER>(leds, NUM_LEDS); //setCorrection(TypicalLEDStrip);
  //FastLED.addLeds<LED_TYPE,DATA_PIN,CLK_PIN,COLOR_ORDER>(leds, NUM_LEDS).setCorrection(TypicalLEDStrip);

  // set master brightness control
  FastLED.setBrightness(BRIGHTNESS);
}

void loop() {
  offset = offset+2;
  //offset = beatsin8(35, 0, 255);

  for (int x = 0; x < LED_COLS; x++) {
    for (int y = 0; y < LED_ROWS; y++) {
      // XY tells us the index of a given X/Y coordinate
      int index = XY(x, y);

      // Let's take the X and Y values, and add them together to get the hue
      int hue = x * 10 + y * 10;

      // add the offset so it changes every frame
      hue += offset;
      leds[index] = CHSV(hue, 255, 255);
    }
  }

  FastLED.show();


}

uint16_t XY( uint8_t x, uint8_t y)
{
  uint16_t i;
  if( kMatrixSerpentineLayout == false) {
    i = (y * LED_COLS) + x;
  }
  if( kMatrixSerpentineLayout == true) {
    if( y & 0x01) {
      // Odd rows run backwards
      uint8_t reverseX = (LED_COLS - 1) - x;
      i = (y * LED_COLS) + reverseX;
    } else {
      // Even rows run forwards
      i = (y * LED_COLS) + x;
    }
  }
  return i;
}