Tutorial: Getting Started with Multiplayer - Lumberyard User Guide
PrerequisitesStep 1: Creating a Level and Adding a Sphere and a Box Step 2: Binding Sphere Transform Components to the NetworkStep 3: Connecting a Client to the Server Related Tasks and Tutorials

Tutorial: Getting Started with Multiplayer

Open 3D Engine (O3DE), the successor to Lumberyard, is now available in Developer Preview. Download O3DE or visit the AWS Game Tech blog to learn more.

This tutorial walks you through the steps to create a simple multiplayer test game level. These steps include binding an entity to the network and connecting a client to the host. At the end of the tutorial, you should have a level with a simple network bound entity that is ready for a multiplayer game.

This tutorial guides you through the following tasks:

  • Create a level and add entities.

  • Bind an entity’s Transform component to the network.

  • Connect a client to the server and verify network replication.

Prerequisites

This tutorial assumes the following:

Note

This tutorial uses Visual Studio 2017.

Topics

Step 1: Creating a Level and Adding a Sphere and a Box

Your first step is to create a level and prepare a simple sphere and box shape so that you can test Lumberyard's networking features.

To create a level, sphere, and box

  1. In the Lumberyard Project Configurator, select a project that has the Multiplayer gem enabled, and then click Set as default.

  2. Open Lumberyard Editor, create a level, and enter a name.

    Create a level in Lumberyard Editor.

  3. In the Lumberyard Editor viewport, right-click and choose Create entity.

  4. With the entity selected, click Tools, Entity Inspector. Use the Entity Inspector to name the entity CameraEntity.

  5. Click Add Component.

  6. Select the Camera component to attach it to the entity.

    Attach a Camera component to the camera entity.

  7. In the Lumberyard Editor viewport, right-click and choose Create entity.

  8. With the entity selected, use the Entity Inspector to name the entity SphereEntity.

  9. In the Entity Inspector, click Add Component, Rendering, Mesh to attach a Mesh component to the SphereEntity.

    Adding a Mesh component to the SphereEntity.

  10. In the Mesh component, click the (…) icon next to Mesh asset.

    Click the ellipsis next to Mesh asset

  11. In the Pick Static Mesh window, expand Engine, Objects, default, and select primitive_sphere.cgf.

    In the Pick Static Mesh window, choose primitive_sphere.cgf.

  12. Click OK.

  13. In the viewport, right-click and choose Create entity.

  14. With the entity selected, use the Entity Inspector to name the entity BoxEntity.

  15. In the Entity Inspector, click Add Component, Rendering, Mesh to attach a Mesh component to the BoxEntity.

  16. In the Mesh component, click the (…) icon next to Mesh asset.

  17. In the Pick Static Mesh window, under Engine, Objects, default, select primitive_cube.cgf.

  18. Click OK.

  19. In the viewport, select the SphereEntity. In the Entity Inspector, click Add Component, Physics, Rigid Body Physics.

    Choose the Rigid Body Physics component for the sphere entity

  20. Select the BoxEntity. In the Entity Inspector, click Add Component, Physics, Rigid Body Physics.

  21. Select the SphereEntity. In the Entity Inspector, click Add Component, Physics, Mesh Collider.

    Choose the Mesh Collider component for the sphere entity

  22. Select the BoxEntity. In the Entity Inspector, click Add Component, Physics, Mesh Collider.

  23. In the viewport, move the sphere and box entities above the plane so that they have room to fall.

    To move the sphere and box entities above the plane

    1. In the viewport, select the entity.

    2. On the EditMode toolbar, choose the Move icon.

    3. On the EditMode toolbar, choose the Constrain to Z Axis icon.

    4. In the viewport, drag the item up vertically.

  24. In the Entity Inspector, Rigid Body Physics component, ensure that At rest initially is unchecked. This allows the sphere and box to begin simulating after the level is loaded.

    Ensure that the At rest initially property is unchecked

You now have two simple component entities with rigid body physics in the level that you created.

Step 2: Binding Sphere Transform Components to the Network

After you create the initial level with the sphere and the box, you bind the sphere’s Transform component to the network. This allows the sphere's changes to be replicated over the network to clients.

To bind the sphere’s transform to the network

  1. Select the sphere entity.

  2. In the Entity Inspector, click Add Component, Networking, Network Binding. Adding the NetBinding component to the entity allows the host to replicate the Transform component of the sphere to all clients.

    Add a Network Binding component to an entity.

  3. With the sphere entity selected, in the Transform component, ensure that the Network Sync, Sync to replicas property is enabled.

    Ensure that Sync to replicas property is enabled

You have now created a server authoritative sphere entity that enables changes to the sphere to replicate over the network. However, you didn't bind the box to the network, so changes in the box will remain unreplicated.

Step 3: Connecting a Client to the Server

This step shows you how to connect a client to the server instance and then observe your networked sphere in action.

To connect a client game to the host game

  1. In Lumberyard Editor, choose Game, Export to Engine, or press Ctrl+E to export your level.

  2. Run the game launcher from the Bin directory that you are using. The name of your launcher is your_game_project_nameLauncher.exe.

    For Visual Studio 2017, the directory is lumberyard_version\dev\Bin64vc141\.

    For Visual Studio 2019, the directory is lumberyard_version\dev\Bin64vc142\.

  3. Press the ` key (above the Tab key) to open the console.

  4. Run the command map MultiplayerTutorial where MultiplayerTutorial is the name of the level to load.

    Run the map command

  5. Press the ` key to open the console. Run the command mphost to make your client host a network session.

    Run the mphost command

  6. Move the first launcher window to one side so that you will be able to see the second launcher window. Use the launcher again to open a second instance of the game. Press the ` key to open the second console.

  7. Run the command sv_port 0 to set the client port to 0 (the ephemeral port).

    Note

    On a single computer, only one process is allowed to bind to a particular port. Therefore, to run more than one game process on the same computer (as in this multiplayer sample), you must use ephemeral ports. The sv_port console variable defines the UDP port on the local machine for the multiplayer sample, and the setting of 0 specifies the ephemeral port. This allows two clients on the same computer to talk to each other.

  8. Run the command mpjoin to join to the host game. You should see the sphere synchronized by location on the client. However, the box will be desynchronized and have different locations on the client and host.

    Synchronized sphere

You have successfully created a simple networked level. You can now use the Network Binding component to connect clients to servers and synchronize transforms of entities.

You have created a simple networking sample to see the effects of networking in Lumberyard. See the following to learn more about what else you can add to your game: