let w = 20;

let current;

​

function setup() {

  createCanvas(400, 800);

  grid = make2DArray(10, 20);

  current = new Piece();

}

​

function draw() {

  background(220);

  current.show();

  current.update();

  drawGrid();

}

​

function drawGrid() {

  for (let i = 0; i < 10; i++) {

    for (let j = 0; j < 20; j++) {

      if (grid[i][j] != 0) {

        fill(255, 0, 0);

        rect(i * w, j * w, w, w);

      }

    }

  }

}

​

function make2DArray(cols, rows) {

  let arr = new Array(cols);

  for (let i = 0; i < arr.length; i++) {

    arr[i] = new Array(rows);

    for (let j = 0; j < arr[i].length; j++) {

      arr[i][j] = 0;

    }

  }

  return arr;

}

​

class Piece {

  constructor() {

    this.x = 5;

    this.y = 0;

    this.speed = 1;

  }

  show() {

    fill(255);

    rect(this.x * w, this.y * w, w, w);

  }

  update() {

    if (frameCount % this.speed == 0) {

      if (this.y < height / w - 1 && grid[this.x][this.y + 1] == 0) {

        this.y++;

      } else {

        grid[this.x][this.y] = 1;

        current = new Piece();

      }

    }

  }

​

  move(dir) {

    if (dir === 'LEFT' && this.x > 0 && grid[this.x - 1][this.y] === 0) {

      this.x--;

    } else if (dir === 'RIGHT' && this.x < width / w - 1 && grid[this.x + 1][this.y] === 0) {

      this.x++;

    }

  }

}

​

function keyPressed() {

  if (keyCode === LEFT_ARROW) {

    current.move('LEFT');

  } else if (keyCode === RIGHT_ARROW) {

    current.move('RIGHT');

  }

}

​