<cat>Code.Misc</cat> <title>Event System</title> The event system is like the Hook system in Garry's Mod. It allows you to register functions on classes to receive a callback on certain global events. ## Registering a callback Adding an `[Event]` attribute will add it to the list to be called. ``` [Event( "server.tick" )] public void MyCallback() { // will get called every server tick } ``` ## Engine events The various events called from the engine currently: ### buildinput Called clientside every frame to process input and encode outputs into a user command. ```csharp [Event.BuildInput] public void MyBuildInput( InputBuilder input ) { } ``` ### client.disconnect Called when a client disconnects. ```csharp [Event( "client.disconnected" )] ``` Called from `GameLoop.ClientDisconnected` ### frame Called just before the beginning of a rendering frame. ```csharp [Event.Frame] ``` Called from `GameLoop.PreRender` ### tick Called every <page text="server or client tick">GameLoop#everytick</page> (60 times a second by default). ```csharp [Event.Tick] [Event( "server.tick" )] [Event( "client.tick" )] ``` Called from `GameLoop.ServerFrame_Think` and `GameLoop.ClientFrame_Think`. ### physics.step Called after each physics step, this is usually every tick but can be more depending on <page text="Global.PhysicsSubSteps">Sandbox.Global.PhysicsSubSteps</page>. ```csharp [Event( "physics.step" )] ``` Called from `GameLoop.PostPhysicsStep`. ### hotloaded Called each time your C# is hotloaded after successful recompile. ```csharp [Event.Hotload] ``` Called from `HotloadManager.DoSwap`. ## Custom Events You can register your own custom event callbacks and call them. ```csharp [Event( "mygame.gameover" )] public void OnGameOver() { } public void DoGameOver() { Event.Run( "mygame.gameover" ) } ``` ### Event arguments Events can pass any amount of arguments too. ⤶ <bug issue="94">Passing arguments in the Event system doesn't work proprely at the moment (or only for events declared and called in the same file). More information here: https://github.com/Facepunch/sbox-issues/issues/94</bug>⤶ ```csharp [Event( "mygame.gameover" )] public void OnGameOver( Player winner ) { } public void DoGameOver( Player winner ) { Event.Run( "mygame.gameover", winner ) } ``` ### EventAttributes If you want, you can also make your own custom EventAttributes (like `[Event.Tick]`) and use them to register handlers. The behavior is the same as raw event names but they have all the benefits of a type (picked up by IntelliSense, checked at compile time, etc.) ```csharp // Defining the event type public static class GameEvent { public const string Custom = "custom"; public class CustomAttribute : EventAttribute { public CustomAttribute() : base(Custom) { } } } // Register it like this [GameEvent.Custom] public void OnCustomEvent() { // do something } // Fire it like this Event.Run(GameEvent.Custom); ```