Unreal

Introduction

Planetary Processing provides a plugin for Unreal Engine 5. The plugin consists of a number of C++ classes for use in connecting players to your game simulation, as well as communicating simulation state to your game client and messages from the client to your simulation.

Pre-requisites

• Unreal Engine 5.4+ (Note: the update for Unreal Engine 5.5 is still in development. Please use 5.4).

• macOS or Windows, the PP Unreal plugin does not currently support Linux.

Installation

To install the Planetary Processing plugin, you must first download the plugin files from our website, you will need to be logged into your Planetary Processing account to do so, the link is: https://files.planetaryprocessing.io/builds/downloads/artefactid/107/version/latest/dist/dist.tar

You'll need then to extract this and move the contents of the lib directory into a directory called PlanetaryProcessing in the Plugins directory at the root level of your project. You'll need to create the Plugins directory if it does not already exist.

You can now enable the Planetary Processing plugin for your Unreal Engine 5 project. You will be required to restart the engine once you enable the plugin.

Classes

PlanetaryProcessing Class

This class is the core of the Planetary Processing plugin. It handles initialization, connection to the server, authentication, message sending, and state updates from the server. This class is intended to be used as a singleton, and instantiated via the Init static function.

Entity Class

This class represents an Entity in the Planetary Processing system. It contains all the data of the corresponding entity on your game server. The Entity Types can be matched up with the EntityActor class using the Entity Map variable.

EntityActor Class

This class extends the Unreal Engine Actor class, spawning an Actor in your game client based on an Entity from your game simulation. You are intended to subclass Entity Actor to create Actors for each of your Entity Types. As an example, a 'Tree' class could be an Entity Actor for a 'tree' Entity Type. Meanwhile a 'Cat' class could be a completely different Entity Actor with a separate mesh component and behaviours.

The EntityActor class is intended to have an Entity associated with it once created, via SetEntity. With this set, the EntityActor class will automatically broadcast OnUpdated and OnRemoved events accordingly, as its associated Entity is either updated or removed.

MessageData Class

The MessageData class is designed to serve as a flexible container for arbitrary data, akin to JavaScript objects. Its primary purpose is twofold:

• Deserialization from JSON: It allows update messages received from the server in JSON format to be efficiently parsed and stored in a way that can be accessed within Unreal Engine. This ensures that the data stored on each Entity (strings, numbers, booleans, arrays and nested objects) can be translated into native Unreal Engine data structures.
• Serialization to JSON: Conversely, the class enables the construction of arbitrary data structures which can be serialized and sent to the server as the body of the message in a SendMessage call.

Hence it can be used in Blueprints to both access data on Entity instances and construct messages for SendMessage.

If you want to handle serialization and deserialization yourself, without MessageData, the original JSON of an Entity is available in the DataJSON property of that class. Raw JSON messages can also be sent using the SendJSONMessage function of the PlanetaryProcessing class.

Blueprints

The Planetary Processing plugin is packaged with a number of example Blueprints. These serve to show how to carry out some basic functions using the Planetary Processing plugin. These blueprints are PP_ExamplePlayerController, PP_ExampleEntityActor, and the PP_ExampleLoginWidget.

PP_ExamplePlayerController

This blueprint demonstrates how to initialize your Planetary Processing instance and then how to carry out the fundamental processes required to make use of it. These include establishing the connection, initializing entities, maintaining the connection, and processing messages to and from the server.

Authentication

There are two stages to authentication: initializing the connection the game server and joining the validated connection's processing.

Authentication

Initializing the connection:

1. Event BeginPlay/Show Login -> Init -> Set

   • Initialize the PlanetaryProcessing singleton with a Game ID (Game ID available in the Planetary Processing Panel).
2. Create PP Example Login Widget Widget -> Set -> Add to Viewport

   • Create an instance of PP_ExampleLoginWidget and adds it to the viewport.
3. Planetary Processing Instance -> Bind Event to On Authenticated -> OnAuthenticated_Event

   • Bind the connection joining processes to the OnAuthenticated event triggered from the PlanetaryProcessing singleton.

Joining a valid connection:

1. OnAuthenticated_Event -> Delay

   • A short delay ensures subsequent bindings are handled by the game thread.

2. Login Widget Instance -> Remove from Parent -> Set

   • Remove the login widget from the viewport.

3. Unbind All Events from On Authenticated -> Planetary Processing Instance

   • Unbind all events from the OnAuthenticated event.
4. Planetary Processing Instance - > Bind Event to On Entity Added -> Bind Event to On Connection Error

   • Set up bindings to generate the game server world using the OnEntityAdded and OnConnectionError events from the PlanetaryProcessing singleton.
5. Start Game -> Start Game (Custom Event)

   • Continue with game logic, in this case a custom event named StartGame.

Entity Actor Spawning

Entity Actor Spawning

1. OnEntityAdded_Event -> GetType / Entity Map -> Find

   • Look up the EntityActor class reference in the EntityMap variable using the Entity Type from the OnEntityAdded_Event.
2. GetLocationVector -> Make Transform

   • Use the GetLocationVector function of the added Entity to create a Vector for the initial location of the EntityActor.
3. Find / Branch / Make Transfrom -> Spawn Actor

   • If the Type is valid, spawn an instance of the EntityActor.
4. OnEntityAdded_Event / Spawn Actor -> Set Entity

   • Call SetEntity on the EntityActor to associate it with the Entity that we are representing.

If you wish, you can extend the script to remove spawning for the client player entity. This can be done by adding an extra branch to filter entities with the same ID as the Planetary Processing instance's UUID. This only removes the player's own entity from the client, not other players.

Connection Error Handling

If the connection fails, cease processing the world and return to the authentication login.

Connection Error Handling

1. OnConnectionError_Event / Planetary Processing Instance -> Unbind All Events from On Entity Added / Planetary Processing Instance -> Unbind All Events from On Connection Error

   • Unbinds all events from OnEntityAdded and OnConnectionError.
2. Show Login -> Show Login Custom Event

   • Calls a custom event called ShowLogin, which feeds back into the authentication flow above.

Update Entities

Update Entities

1. Planetary Processing Instance -> IsAuthenticated / Event Tick -> Branch

   • On each tick, check if the connection is authenticated by calling IsAuthenticated on the PlanetaryProcessing instance.
2. Branch -> Sequence / Planetary Processing Instance -> Update -> OnUpdated_Event

   • If it is authenticated, call the Update function of the PlanetaryProcessing instance to process state changes received.
3. Sequence -> Send Player Coords -> SendPlayerCoords (Custom Event)

   • We then also call the SendPlayerCoords custom event.

Send Player Coordinates Message

Send Player Coordinates Message

1. Send Player Coords (Custom Event) -> ...

   • Process the message on each update tick using the Send Player Coords broadcast.
2. Get Player Pawn -> Get Actor Location

   • Get the location of the Player Pawn Actor.

3. Convert Vector To Server Coords Message Data -> Set

   • Call the ConvertVectorToServerCoordsMessageData static function from the PlanetaryProcessing class. This gives us a map of strings to MessageData values, with the x, y and z values set based on the player position. ConvertVectorToServerCoordsMessageData alters these xyz values to match the Planetary Processing coordinate system orientation.
4. Set / To MessageData (bool) -> Add

   • Uses the implicit conversion of a boolean to MessageData as the value for a new key of threedee in our map.
5. Add / Planetary Processing Instance / Set -> Send Message

   • Calls SendMessage on our PlanetaryProcessing instance with our message map as an argument.

PP_ExampleEntityActor

This blueprint shows how to bind to the OnUpdated and OnRemoved events for an EntityActor.

Event Binding

Entity Actor Event Binding

1. Event BeginPlay -> Bind Event to On Updated -> OnUpdated_Event -> Set Actor Location to Entity Coords

   • Bind to the OnUpdated event for the EntityActor. Calls SetActorLocationToEntityCoords to update the Actor's location to match the Entity.
2. Bind Event to On Removed -> OnRemoved_Event -> Destroy Actor

   • Bind to the OnRemoved event for the EntityActor. Destroys the Actor when this event is broadcast.

For the actor to follow the server-side location, without issue, it must have physics disabled on the clientside.

If you wish to retrieve the location vector of an entity before it is set, you can do so with the following example. Replace the Print String function with functions of your choice. This is useful for smoothing movement on the client side.

PP_ExampleLoginWidget

This is a simple login widget which calls the Connect function and displays an error if the connection fails.

Login Click

Login Click

1. OnClicked (Login_Button) / Error Message Text -> Set Visibility

   • Hide the error message (effectively resetting the error state of the login form) when clicked.

2. Username / Password -> GetText -> Get Planetary Processing Instance / To String (Text) -> Connect

   • Call the Connect function on the PlanetaryProcessing instance with the username and password from the login form.

Error Handling

Login Error Handling

1. Event On Initialized -> Get Planetary Processing Instance -> Bind Event to On Connection Error -> OnConnectionError_Event

   • Bind to the OnConnectionError event when the widget is initialized.
2. OnConnectionError_Event / Error Message Text -> Set

   • Set the error message to be visible when OnConnectionError is broadcast.

API

PlanetaryProcessing Class

Properties

Name	Type	Description
GameID	int32	ID of the game. Editable in Blueprints.
UUID	FString	Authenticated player's unique identifier. Read-only in Blueprints.
Entities	TMap<FString, UEntity*>	Map of server entities, reflecting the server state as of the latest update. Read-only in Blueprints.

Functions

Name	Parameters	Return Type	Description
static Init	int32 InGameID	UPlanetaryProcessing*	Initializes the Planetary Processing singleton with the given game ID. If called again, the existing Planetary Processing instance will be restored to its initial state and returned.
static GetInstance	None	UPlanetaryProcessing*	Gets the singleton instance of the Planetary Processing class.
Connect	const FString& Username, const FString& Password	void	Connects the player to the server with the provided username and password. Broadcasts OnAuthenticated upon successful connection.
Update	None	void	Updates the Entities map by processing state updates that the client has received from the server since the last update. Intended to be called once each game tick such that the Entities map consists of fresh data. Broadcasts OnEntityAdded, OnEntityUpdated and OnEntityRemoved
IsAuthenticated	None	bool	Returns whether the user is authenticated.
IsConnected	None	bool	Returns whether the initial socket connection to the server is active.
SendMessage	const TMap<FString, UMessageData*>& Message	void	Sends a message to the server, using the MessageData format.
SendJSONMessage	const FString& JsonString	void	Sends a JSON message to the server. This can be used if your data is already in JSON format and as such can be sent directly.
Logout	None	void	Logs out and disconnects the player from the server.
static ConvertVectorToServerCoords	const FVector& InVector	TMap<FString, float>	Converts an Unreal Engine Vector into the coordinate system used in Planetary Processing.
static ConvertVectorToServerCoordsMessageData	const FVector& InVector	TMap<FString, UMessageData*>	Converts an Unreal Engine Vector into MessageData with x, y and z values set in the Planetary Processing coordinate system.

Delegates

Delegate	Parameter	Description
OnAuthenticated	None	Fires when player is successfully authenticated.
OnEntityAdded	UEntity* NewEntity	Fires when a new Entity is added to the Entities map. This can be used to spawn a new EntityActor.
OnEntityUpdated	UEntity* UpdatedEntity	Fires when an existing Entity in the Entities map is updated. If an EntityActor has already been spawned based on this Entity, the EntityActor will re-broadcast this as an OnUpdated event.
OnEntityRemoved	const FString& EntityID	Fires when an Entity is removed from the Entities map. If an EntityActor has been spawned based on this Entity, the EntityActor will re-broadcast this as an OnRemoved event.
OnConnectionError	const FString& ErrorMessage	Currently a catch-all for connection related errors, including authentication errors, loss of connection, failure to send messages or failure to parse updates.

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Entity Class

Properties

Name	Type	Description
ID	FString	The unique identifier of the entity.
X	double	X coordinate of the entity.
Y	double	Y coordinate of the entity.
Z	double	Z coordinate of the entity.
Data	TMap<FString, UMessageData*>	Additional data of the entity.
DataJSON	FString	JSON representation of the additional entity Data.
Type	FString	Type of the entity.

Functions

Name	Parameters	Return Type	Description
GetLocationVector	None	FVector	Converts the Planetary Processing X, Y and Z coordinates of this entity into a Vector in the Unreal Engine coordinate system

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EntityActor Class

Properties

Name	Type	Description
Entity	UEntity*	The entity associated with this actor.
OnUpdated	FOnEntityUpdatedEvent	Delegate called when the entity is updated.
OnRemoved	FOnEntityRemovedEvent	Delegate called when the entity is removed.

Functions

Name	Parameters	Return Type	Description
SetEntity	UEntity* InEntity	void	Sets the entity for this actor.
SetActorLocationToEntityCoords	None	void	Converts the Planetary Processing X, Y and Z coordinates of the associated Entity into a Vector in the Unreal Engine coordinate system and sets the Actor's location to this Vector

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MessageData Class

Functions

Name	Parameters	Return Type	Description
static ConvertBoolToMessageData	bool Value	UMessageData*	Implicit conversion of a boolean value to a MessageData instance.
static ConvertIntToMessageData	int32 Value	UMessageData*	Implicit conversion of an integer value to a MessageData instance.
static ConvertFloatToMessageData	float Value	UMessageData*	Implicit conversion of a float value to a MessageData instance.
static ConvertStringToMessageData	const FString& Value	UMessageData*	Implicit conversion of a string value to a MessageData instance.
static ConvertArrayToMessageData	const TArray<UMessageData*>& Value	UMessageData*	Implicit conversion of an array of MessageData instances to a MessageData instance.
static ConvertObjectToMessageData	const TMap<FString, UMessageData*>& Value	UMessageData*	Implicit conversion of a map of MessageData instances to a MessageData instance.
GetString	None	FString	Returns the stored string value, if type is String.
GetDouble	None	double	Returns the stored double value, if type is Double.
GetInt	None	int32	Returns the stored integer value, if type is Int.
GetBool	None	bool	Returns the stored boolean value, if type is Bool.
GetObject	None	TMap<FString, UMessageData*>	Returns the stored object value, if type is Object.
GetArray	None	TArray<UMessageData*>	Returns the stored array value, if type is Array.
GetActiveType	None	EVariantType	Returns the active variant type of the message data.
SerializeToJson	None	FString	Serializes the message data to JSON format.
static SerializeMapToJson	const TMap<FString, UMessageData*>& Map	FString	Serializes a map of UMessageData to JSON format.
DeserializeFromJson	const FString& JsonString	void	Deserializes JSON string into message data.

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PP_ExamplePlayerController

Variables

Name	Type	Description
PlanetaryProcessingInstance	Planetary Processing Object Reference	Reference to the Planetary Processing singleton.
LoginWidgetInstance	PP Example Login Object Reference	Stores a reference to the Login Widget when it is shown.
LocationMessage	Map<string: Message Data Object Reference>	A message to be used in a call to SendMessage.
EntityMap	Map<string: Entity Actor Class Reference>	Used to map Entity types to the Entity Actor they should spawn. The default values for this variable map both cat and tree to the PP_ExampleEntityActor as a demonstration.

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PP_ExampleLoginWidget

Variables

Name	Type	Description
Username	UEditableTextBox	A text box widget for entering a username.
Password	UEditableTextBox	A text box widget for entering a password.
Login_Button	UButton	A button widget for triggering the OnClicked event, to connect to the game server.
ErrorMessageText	UTextBlock	Error text displayed, when a connection fails