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Modding:Modder Guide/APIs/Multiplayer (view source)
Revision as of 02:59, 23 January 2021
, 02:59, 23 January 2021→Per-screen data: expand info + example, add new features in SMAPI 3.9
[[Multiplayer|Split-screen multiplayer]] swaps the entire game state between each player, so each mod runs across every player. For example, with four local players the [[Modding:Modder Guide/APIs/Events#GameLoop.UpdateTicked|<tt>UpdateTicked</tt>]] event would be raised four times per tick. The game manages its own state automatically (e.g. <tt>Game1.activeClickableMenu</tt>), but if your mod stores info in its own fields you may need to handle those yourself.
[[Multiplayer|Split-screen multiplayer]] swaps the entire game state between each player, so each mod runs across every player. For example, with four local players the [[Modding:Modder Guide/APIs/Events#GameLoop.UpdateTicked|<tt>UpdateTicked</tt>]] event would be raised four times per tick. The game manages its own state automatically (e.g. <tt>Game1.activeClickableMenu</tt>), but if your mod stores info in its own fields you may need to handle those yourself.
SMAPI provides <code>PerScreen<T></code> to make that easy. You use it by creating '''readonly''' fields for your values (which can be any value from <tt>int</tt> to entire class instances):
<source lang="C#">
private readonly PerScreen<int> LastPlayerId = new PerScreen<int>(); // defaults to 0
private readonly PerScreen<SButton> LastButtonPressed = new PerScreen<SButton>(createNewState: () => SButton.None); // defaults to the given value
</source>
For example, this mod would keep track of the last button pressed by each player:
Then you can just use its properties and methods:
{| class="wikitable"
|-
! member
! description
|-
| <code>Value</code>
| Get or set the value for the current screen. If needed, this creates the value automatically.
|-
| <code>GetActiveValues()</code>
| Get the screen IDs and values for every active screen which has a value.
|-
| <code>GetValueForScreen(screenId)</code><br /><code>SetValueForScreen(screenId, value)</code>
| Get or set the value for a specific screen ID, creating it if needed.
|-
| <code>ResetAllScreens</code>
| Clear the values saved for every screen.
|}
===Example===
For example, this mod plays a simple game: the main player presses a key, and farmhands need to guess which key was pressed.
<source lang="C#">
<source lang="C#">
{
{
private readonly PerScreen<SButton> LastButtonPressed = new PerScreen<SButton>();
private readonly PerScreen<SButton> LastButtonPressed = new PerScreen<SButton>();
private readonly PerScreen<int> Score = new PerScreen<int>();
public override void Entry(IModHelper helper)
public override void Entry(IModHelper helper)
private void OnButtonPressed(object sender, ButtonPressedEventArgs e)
private void OnButtonPressed(object sender, ButtonPressedEventArgs e)
{
{
this.LastButtonPressed.Value = e.Button;
// main player changes key
if (Context.IsMainPlayer)
{
this.LastButtonPressed.Value = e.Button;
this.Monitor.Log("The main player changed the key. Can you guess it?", LogLevel.Info);
}
// farmhands try to guess the key
else
{
SButton correctButton = this.LastButtonPressed.GetValueForScreen(0);
if (correctButton != SButton.None)
{
if (e.Button == correctButton)
{
this.Score.Value++;
this.LastButtonPressed.SetValueForScreen(0, SButton.None);
this.Monitor.Log($"Player #{Context.ScreenId + 1} correctly guessed the key: {e.Button}! Their score is now {this.Score.Value}.", LogLevel.Info);
}
else
this.Monitor.Log($"Player #{Context.ScreenId + 1} guessed incorrectly: {e.Button}.", LogLevel.Debug);
}
}
}
}
}
}
</source>
</source>