half-earth/nodes/clock.tscn

@@ -4,3 +4,4 @@
 
 [node name="Clock" type="Node"]
 script = ExtResource( 1 )
+_tickRate = 10.0

half-earth/nodes/debug_ui.tscn

@@ -7,6 +7,7 @@ anchor_right = 1.0
 anchor_bottom = 1.0
 script = ExtResource( 1 )
 TicksLabelPath = NodePath("Ticks")
+PauseLabelPath = NodePath("Paused")
 
 [node name="Ticks" type="Label" parent="."]
 anchor_left = 1.0
@@ -14,9 +15,22 @@ anchor_top = 1.0
 anchor_right = 1.0
 anchor_bottom = 1.0
 margin_right = -10.0
+margin_bottom = -30.0
+grow_horizontal = 0
+grow_vertical = 0
+text = "ticks: 0"
+align = 2
+valign = 2
+
+[node name="Paused" type="Label" parent="."]
+anchor_left = 1.0
+anchor_top = 1.0
+anchor_right = 1.0
+anchor_bottom = 1.0
+margin_right = -10.0
 margin_bottom = -10.0
 grow_horizontal = 0
 grow_vertical = 0
-text = "ticks: 0"
+text = "pause: false"
 align = 2
 valign = 2

half-earth/nodes/game.tscn

@@ -8,6 +8,7 @@
 [node name="Root" type="Node"]
 
 [node name="Grid" parent="." instance=ExtResource( 1 )]
+DiffusionCoefficient = 0.1
 
 [node name="Cursor" parent="." instance=ExtResource( 2 )]
 Grid = NodePath("../Grid")
@@ -15,6 +16,8 @@ Grid = NodePath("../Grid")
 [node name="Debug UI" parent="." instance=ExtResource( 3 )]
 
 [node name="Clock" parent="." instance=ExtResource( 4 )]
+_autoTick = true
 
+[connection signal="OnPauseChanged" from="Clock" to="Debug UI" method="_on_Clock_OnPauseChanged"]
 [connection signal="OnTick" from="Clock" to="Grid" method="_on_Clock_OnTick"]
 [connection signal="OnTick" from="Clock" to="Debug UI" method="_on_Clock_OnTick"]

half-earth/scripts/Clock.cs

@@ -5,8 +5,18 @@ public class Clock : Node
 {
     [Signal]
     delegate void OnTick(int ticks);
-    
+    [Signal]
+    delegate void OnPauseChanged(bool paused);
+
+    [Export(PropertyHint.None, "Number of ticks per second")]
+    private float _tickRate;
+    private float TickPeriod => 1.0f / _tickRate;
+
+    [Export]
+    private bool _autoTick;
+
     private int _ticks = 0;
+    private bool _paused = false;
 
     public override void _Input(InputEvent @event)
     {
@@ -17,12 +27,38 @@ public class Clock : Node
             switch ((KeyList)keyEvent.Scancode)
             {
                 case KeyList.Space:
+                    if (_autoTick)
+                    {
+                        _paused = !_paused;
+                        EmitSignal(nameof(OnPauseChanged), _paused);
+                        return;
+                    }
                     Tick();
                     break;
             }
         }
     }
-    
+
+    private float _secondsSinceLastTick;
+
+    public override void _Process(float delta)
+    {
+        base._Process(delta);
+
+        if (!_autoTick)
+            return;
+
+        if (_paused)
+            return;
+
+        _secondsSinceLastTick += delta;
+        if (_secondsSinceLastTick < TickPeriod)
+            return;
+
+        _secondsSinceLastTick -= TickPeriod;
+        Tick();
+    }
+
     private void Tick()
     {
         _ticks++;

half-earth/scripts/DebugUI.cs

@@ -6,17 +6,32 @@ public class DebugUI : Control
     [Export]
     public NodePath TicksLabelPath { private get; set; }
     private Label _ticksLabel;
-    
+
+    [Export]
+    public NodePath PauseLabelPath { private get; set; }
+    private Label _pauseLabel;
+
     public override void _Ready()
     {
         _ticksLabel = GetNode<Label>(TicksLabelPath);
+        _pauseLabel = GetNode<Label>(PauseLabelPath);
+
         SetTicksText(0);
+        SetPauseText(false);
     }
-    
+
+    #region Signals
+    public void _on_Clock_OnPauseChanged(bool paused) => SetPauseText(paused);
     public void _on_Clock_OnTick(int ticks) => SetTicksText(ticks);
-    
+    #endregion
+
     private void SetTicksText(int ticks)
     {
         _ticksLabel.Text = $"ticks: {ticks}";
     }
+
+    private void SetPauseText(bool paused)
+    {
+        _pauseLabel.Text = $"pause: {paused}";
+    }
 }