#include "FastLED.h"

// Matrix size
#define NUM_ROWS 10
#define NUM_COLS 10

// LEDs pin
#define DATA_PIN 3

// LED brightness
#define BRIGHTNESS 180

#define NUM_LEDS NUM_ROWS * NUM_COLS

// Define the array of leds
CRGB leds[NUM_LEDS];

void setup() {
  FastLED.addLeds<NEOPIXEL, DATA_PIN>(leds, NUM_LEDS);
  FastLED.setBrightness(BRIGHTNESS);
}

void loop() {
  DrawRow();
  FastLED.clear();
}

void DrawRow() {
  int speed = 200;
  int y ;
  int x ;
  int hw = NUM_COLS / 2;
  for (y = NUM_ROWS; y >= 0; y--) {
    for(x = 0; x < hw; x++) {
      if(y > 0) {
        leds[(y-1)*NUM_ROWS + x] = CRGB::White;
      }
      if(y < NUM_ROWS) {
        leds[y*NUM_ROWS + x + hw] = CRGB::White;
      }
      FastLED.delay(speed);
      FastLED.show();
    }
  }
}