Dynamic Tilemap To Render Texture

var config = {
    type: Phaser.AUTO,
    parent: 'phaser-example',
    width: 800,
    height: 600,
    scene: {
        preload: preload,
        create: create,
        update: update
    }
};

var rt;
var layer;

var game = new Phaser.Game(config);

function preload ()
{
        this.load.setBaseURL('https://cdn.phaserfiles.com/v355');
    this.load.image('tiles', 'assets/tilemaps/tiles/tmw_desert_spacing.png');
    this.load.tilemapTiledJSON('map', 'assets/tilemaps/maps/desert.json');
}

function create ()
{
    map = this.make.tilemap({ key: 'map' });

    var tiles = map.addTilesetImage('Desert', 'tiles');

    layer = map.createLayer('Ground', tiles, 0, 0).setVisible(false);

    rt = this.add.renderTexture(0, 0, 800, 600);
}

function update ()
{
    rt.camera.rotation -= 0.01;

    rt.clear();

    rt.draw(layer);
}