GMnet - Manual

8. A second room and doors

Now you know nearly everything needed to make a very simple multiplayer game.

The next sections will cover the following more advanced, but still not very difficult, topics:

Using the multiplayer engine with mutliple rooms
Working with the data of the multiplayer engine

We are now going to create a second room. Simply copy htme_rom_demo and restructure the walls a bit. Maybe you could also change the background color. Remove all other objects from the room, except the walls and htme_obj_network_controller.

There are two aproaches you could use if you want the player to enter this room:

Place a new player instance in htme_rom_demo2, make the player object NOT persistent
Make the player instance persistent; Persistent objects in Game Maker exist even after you change the room.

For this tutorial we are using the second approach. The reason for that, is that we also want to teach you, how persistent objects work with the instance. But if you solve your game using the first method, this should also work in most cases. Please note that the second approach is recommend though.

Make your htme_obj_player persistent. That's all we need to do in the player object if we want him to move to a second room.

Now create the object htme_obj_door with the spritehtme_spr_door.

Create a Collsion with htme_obj_player event and add this code:

///CHECK IF DOOR ENTERED
var isLocal;
with (other) {isLocal = htme_isLocal();}

if (isLocal && keyboard_check_pressed(vk_up)) {
    var dest = htme_rom_demo2;
    if (room == htme_rom_demo2) dest = htme_rom_demo;
    room_goto(dest);
}

This checks when a player is standing in front of a door if the other instance, which is an instance of the object htme_obj_player is our local player by storing this information in the local variable isLocal. When it's our local player ("we") we change the room. The room is changed to htme_rom_demo2 when in htme_rom_demo and viceversa. Place a door in each room.

We are done.

Now start a client and server again and try switching rooms. Everything should work as you would expect it. If not, check again if you made the player object persistent and make sure the doors are on the same position in both rooms.

Some technical stuff

When you make persistent objects, they are only persistent locally.

That means when another player switches room, they will cease to exist in your game. When you enter the room they will be resent and recreated to your client.

Here is a nice little table FOR AN INSTANCE CREATED BY A IN ROOM 1:

The table