Add basic multiplayer functionality

- Can now create servers and connect with clients
- Add OtherPlayer scene
- Add static Extension class for extension methods

scene/EscapeMenu.tscn

@@ -28,22 +28,22 @@ anchor_right = 1.0
 anchor_bottom = 1.0
 
 [node name="PanelContainer" type="PanelContainer" parent="CenterContainer"]
-margin_left = 527.0
+margin_left = 522.0
 margin_top = 274.0
-margin_right = 752.0
+margin_right = 757.0
 margin_bottom = 446.0
 
 [node name="VBoxContainer" type="VBoxContainer" parent="CenterContainer/PanelContainer"]
 margin_left = 7.0
 margin_top = 7.0
-margin_right = 218.0
+margin_right = 228.0
 margin_bottom = 165.0
 __meta__ = {
 "_edit_use_anchors_": false
 }
 
 [node name="Label" type="Label" parent="CenterContainer/PanelContainer/VBoxContainer"]
-margin_right = 211.0
+margin_right = 221.0
 margin_bottom = 9.0
 text = "Pause Menu"
 align = 1
@@ -53,12 +53,12 @@ __meta__ = {
 
 [node name="HSeparator" type="HSeparator" parent="CenterContainer/PanelContainer/VBoxContainer"]
 margin_top = 13.0
-margin_right = 211.0
+margin_right = 221.0
 margin_bottom = 17.0
 
 [node name="ContainerStatus" type="HBoxContainer" parent="CenterContainer/PanelContainer/VBoxContainer"]
 margin_top = 21.0
-margin_right = 211.0
+margin_right = 221.0
 margin_bottom = 34.0
 
 [node name="Label" type="Label" parent="CenterContainer/PanelContainer/VBoxContainer/ContainerStatus"]
@@ -70,8 +70,9 @@ text = "Status:"
 align = 2
 
 [node name="Status" type="Label" parent="CenterContainer/PanelContainer/VBoxContainer/ContainerStatus"]
+modulate = Color( 1, 0, 0, 1 )
 margin_left = 40.0
-margin_right = 211.0
+margin_right = 221.0
 margin_bottom = 13.0
 rect_min_size = Vector2( 0, 13 )
 size_flags_horizontal = 3
@@ -85,7 +86,7 @@ __meta__ = {
 
 [node name="ContainerServer" type="HBoxContainer" parent="CenterContainer/PanelContainer/VBoxContainer"]
 margin_top = 38.0
-margin_right = 211.0
+margin_right = 221.0
 margin_bottom = 57.0
 
 [node name="Label" type="Label" parent="CenterContainer/PanelContainer/VBoxContainer/ContainerServer"]
@@ -110,7 +111,7 @@ __meta__ = {
 
 [node name="ServerStartStop" type="Button" parent="CenterContainer/PanelContainer/VBoxContainer/ContainerServer"]
 margin_left = 94.0
-margin_right = 211.0
+margin_right = 221.0
 margin_bottom = 19.0
 size_flags_horizontal = 3
 text = "Start Server"
@@ -120,7 +121,7 @@ __meta__ = {
 
 [node name="ContainerClient" type="HBoxContainer" parent="CenterContainer/PanelContainer/VBoxContainer"]
 margin_top = 61.0
-margin_right = 211.0
+margin_right = 221.0
 margin_bottom = 80.0
 
 [node name="Label" type="Label" parent="CenterContainer/PanelContainer/VBoxContainer/ContainerClient"]
@@ -141,14 +142,15 @@ caret_blink = true
 
 [node name="ClientDisConnect" type="Button" parent="CenterContainer/PanelContainer/VBoxContainer/ContainerClient"]
 margin_left = 164.0
-margin_right = 211.0
+margin_right = 221.0
 margin_bottom = 19.0
+rect_min_size = Vector2( 57, 0 )
 size_flags_horizontal = 3
 text = "Connect"
 
 [node name="HBoxContainer" type="HBoxContainer" parent="CenterContainer/PanelContainer/VBoxContainer"]
 margin_top = 84.0
-margin_right = 211.0
+margin_right = 221.0
 margin_bottom = 108.0
 
 [node name="HideAddress" type="CheckBox" parent="CenterContainer/PanelContainer/VBoxContainer/HBoxContainer"]
@@ -166,12 +168,12 @@ text = "(for streamers etc.)"
 
 [node name="HSeparator2" type="HSeparator" parent="CenterContainer/PanelContainer/VBoxContainer"]
 margin_top = 112.0
-margin_right = 211.0
+margin_right = 221.0
 margin_bottom = 116.0
 
 [node name="Quit" type="Button" parent="CenterContainer/PanelContainer/VBoxContainer"]
 margin_top = 120.0
-margin_right = 211.0
+margin_right = 221.0
 margin_bottom = 137.0
 rect_min_size = Vector2( 0, 17 )
 
@@ -196,7 +198,7 @@ __meta__ = {
 
 [node name="Return" type="Button" parent="CenterContainer/PanelContainer/VBoxContainer"]
 margin_top = 141.0
-margin_right = 211.0
+margin_right = 221.0
 margin_bottom = 158.0
 rect_min_size = Vector2( 0, 17 )
 __meta__ = {

scene/OtherPlayer.tscn

@@ -0,0 +1,15 @@
+[gd_scene load_steps=3 format=2]
+
+[ext_resource path="res://gfx/player.png" type="Texture" id=2]
+
+[sub_resource type="CircleShape2D" id=1]
+radius = 8.0
+
+[node name="OtherPlayer" type="KinematicBody2D"]
+collision_layer = 0
+
+[node name="CircleShape" type="CollisionShape2D" parent="."]
+shape = SubResource( 1 )
+
+[node name="Sprite" type="Sprite" parent="."]
+texture = ExtResource( 2 )

scene/Player.tscn

@@ -8,11 +8,8 @@
 radius = 8.0
 
 [node name="Player" type="KinematicBody2D"]
-position = Vector2( 640, 360 )
+collision_layer = 0
 script = ExtResource( 3 )
-__meta__ = {
-"_edit_group_": true
-}
 
 [node name="Camera2D" type="Camera2D" parent="."]
 current = true

src/EscapeMenu.cs

@@ -1,8 +1,12 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
 using Godot;
 
+// TODO: Split network and escape menu logic.
 public class EscapeMenu : Container
 {
-    [Export] public int DefaultPort { get; set; } = 25565;
+    [Export] public ushort DefaultPort { get; set; } = 42005;
     [Export] public string DefaultAddress { get; set; } = "localhost";
 
     [Export] public NodePath StatusPath { get; set; }
@@ -19,6 +23,15 @@ public class EscapeMenu : Container
     public LineEdit ClientAddress { get; private set; }
     public Button Return { get; private set; }
 
+    public Node PlayerContainer { get; private set; }
+    public Player OwnPlayer { get; private set; }
+    public PackedScene OtherPlayer { get; private set; }
+
+    public override void _Ready()
+    {
+        OtherPlayer = GD.Load<PackedScene>("res://scene/OtherPlayer.tscn");
+    }
+
     public override void _EnterTree()
     {
         Status           = GetNode<Label>(StatusPath);
@@ -27,9 +40,23 @@ public class EscapeMenu : Container
         ClientDisConnect = GetNode<Button>(ClientDisConnectPath);
         ClientAddress    = GetNode<LineEdit>(ClientAddressPath);
         Return           = GetNode<Button>(ReturnPath);
+        PlayerContainer  = GetNode("/root/Game");
 
         ServerPort.PlaceholderText    = DefaultPort.ToString();
         ClientAddress.PlaceholderText = $"{DefaultAddress}:{DefaultPort}";
+
+        GetTree().Connect("connected_to_server", this, "OnClientConnected");
+        GetTree().Connect("connection_failed", this, "DisconnectFromServer");
+        GetTree().Connect("server_disconnected", this, "DisconnectFromServer");
+
+        GetTree().Connect("network_peer_connected", this, "OnPeerConnected");
+        GetTree().Connect("network_peer_disconnected", this, "OnPeerDisconnected");
+    }
+
+    public override void _Process(float delta)
+    {
+        if (OwnPlayer == null) return;
+        RpcUnreliable("OnPlayerMoved", OwnPlayer.Position);
     }
 
     public override void _Input(InputEvent @event)
@@ -46,6 +73,7 @@ public class EscapeMenu : Container
     public void Open()
     {
         if (Visible) return;
+        if (GetTree().NetworkPeer == null)
             GetTree().Paused = true;
         Return.GrabFocus();
         Visible = true;
@@ -54,21 +82,171 @@ public class EscapeMenu : Container
     public void Close()
     {
         if (!Visible) return;
+        if (GetTree().NetworkPeer == null)
             GetTree().Paused = false;
         Visible = false;
     }
 
+
+    public void StartServer(ushort port)
+    {
+        if (GetTree().NetworkPeer != null) throw new InvalidOperationException();
+
+        var peer = new NetworkedMultiplayerENet();
+        // TODO: Somehow show there was an error.
+        if (peer.CreateServer(port) != Error.Ok) return;
+        GetTree().NetworkPeer = peer;
+        OwnPlayer = FindOwnPlayer();
+
+        Status.Text     = "Server Running";
+        Status.Modulate = Colors.Green;
+        ServerPort.Editable  = false;
+        ServerStartStop.Text = "Stop Server";
+        ClientAddress.Editable    = false;
+        ClientDisConnect.Disabled = true;
+
+        if (Visible) GetTree().Paused = false;
+    }
+
+    public void StopServer()
+    {
+        if ((GetTree().NetworkPeer == null) || !GetTree().IsNetworkServer()) throw new InvalidOperationException();
+
+        // TODO: Disconnect players gracefully.
+        ((NetworkedMultiplayerENet)GetTree().NetworkPeer).CloseConnection();
+        GetTree().NetworkPeer = null;
+
+        OwnPlayer = null;
+        foreach (var player in GetOtherPlayers())
+            player.RemoveFromParent();
+
+        Status.Text     = "No Connection";
+        Status.Modulate = Colors.Red;
+        ServerPort.Editable  = true;
+        ServerStartStop.Text = "Start Server";
+        ClientAddress.Editable    = true;
+        ClientDisConnect.Disabled = false;
+
+        if (Visible) GetTree().Paused = true;
+    }
+
+    public void ConnectToServer(string address, ushort port)
+    {
+        if (GetTree().NetworkPeer != null) throw new InvalidOperationException();
+
+        var peer = new NetworkedMultiplayerENet();
+        // TODO: Somehow show there was an error.
+        if (peer.CreateClient(address, port) != Error.Ok) return;
+        GetTree().NetworkPeer = peer;
+
+        Status.Text     = "Connecting ...";
+        Status.Modulate = Colors.Yellow;
+        ServerPort.Editable      = false;
+        ServerStartStop.Disabled = true;
+        ClientAddress.Editable = false;
+        ClientDisConnect.Text  = "Disconnect";
+
+        if (Visible) GetTree().Paused = false;
+    }
+
+    public void DisconnectFromServer()
+    {
+        if ((GetTree().NetworkPeer == null) || GetTree().IsNetworkServer()) throw new InvalidOperationException();
+
+        // TODO: Disconnect from server gracefully.
+        ((NetworkedMultiplayerENet)GetTree().NetworkPeer).CloseConnection();
+        GetTree().NetworkPeer = null;
+
+        OwnPlayer = null;
+        foreach (var player in GetOtherPlayers())
+            player.RemoveFromParent();
+
+        Status.Text     = "No Connection";
+        Status.Modulate = Colors.Red;
+        ServerPort.Editable      = true;
+        ServerStartStop.Disabled = false;
+        ClientAddress.Editable    = true;
+        ClientDisConnect.Disabled = false;
+        ClientDisConnect.Text     = "Connect";
+
+        if (Visible) GetTree().Paused = true;
+    }
+
+    private Player FindOwnPlayer()
+        => GetTree().Root.GetChild(0).GetChildren().OfType<Player>().First();
+
+    private Node2D GetPlayerWithId(int id)
+        => PlayerContainer.GetNodeOrNull<Node2D>(id.ToString());
+    private Node2D GetOrCreatePlayerWithId(int id)
+    {
+        var player = GetPlayerWithId(id);
+        if (player == null) {
+            player = (Node2D)OtherPlayer.Instance();
+            // TODO: Use "set_network_master".
+            player.Name = id.ToString();
+            PlayerContainer.AddChild(player);
+        }
+        return player;
+    }
+
+    // TODO: This assumes that any node whose name starts with a digit is a player.
+    private IEnumerable<Node2D> GetOtherPlayers()
+        => PlayerContainer.GetChildren().OfType<Node2D>()
+            .Where(node => char.IsDigit(node.Name[0]));
+
+
     #pragma warning disable IDE0051
+
+    private void OnClientConnected()
+    {
+        OwnPlayer = FindOwnPlayer();
+
+        Status.Text     = "Connected to Server";
+        Status.Modulate = Colors.Green;
+    }
+
+
+    private void OnPeerConnected(int id)
+    {
+
+    }
+
+    private void OnPeerDisconnected(int id)
+        => GetPlayerWithId(id)?.RemoveFromParent();
+
+    [Remote]
+    private void OnPlayerMoved(Vector2 position)
+    {
+        var id     = GetTree().GetRpcSenderId();
+        var player = GetOrCreatePlayerWithId(id);
+        player.Position = position;
+    }
+
+
     #pragma warning disable IDE1006
 
     private void _on_ServerStartStop_pressed()
     {
-
+        if (GetTree().NetworkPeer == null)
+            StartServer((ServerPort.Text.Length > 0) ? ushort.Parse(ServerPort.Text) : DefaultPort);
+        else StopServer();
     }
 
     private void _on_ClientDisConnect_pressed()
     {
+        if (GetTree().NetworkPeer == null) {
+            var address = DefaultAddress;
+            var port    = DefaultPort;
+
+            if (ClientAddress.Text.Length > 0) {
+                // TODO: Verify input some more, support IPv6?
+                var split = address.Split(':');
+                address = (split.Length > 1) ? split[0] : address;
+                port    = (split.Length > 1) ? ushort.Parse(split[1]) : port;
+            }
 
+            ConnectToServer(address, port);
+        } else DisconnectFromServer();
     }
 
     private void _on_HideAddress_toggled(bool pressed)

src/Extensions.cs

@@ -0,0 +1,7 @@
+using Godot;
+
+public static class Extensions
+{
+    public static void RemoveFromParent(this Node node)
+        => node.GetParent().RemoveChild(node);
+}