leveling up

BoundingBoxes/Hurtbox.cs

@@ -11,6 +11,7 @@ public partial class Hurtbox : BoundingBox, IFaction
         float damage,
         Character inflictor,
         float knockback,
+        Items.Weapon weapon = null,
         Vector2 knockbackDir = default);
 
     /// <summary>
@@ -39,6 +40,7 @@ public partial class Hurtbox : BoundingBox, IFaction
         float damage,
         Character inflictor,
         float knockback,
+        Items.Weapon weapon = default,
         Vector2 knockbackOrigin = default,
         Vector2 knockbackVector = default)
     {
@@ -83,6 +85,7 @@ public partial class Hurtbox : BoundingBox, IFaction
             damage,
             inflictor,
             knockback,
+            weapon,
             knockbackDir);
     }
 }

Characters/Character.cs

@@ -308,6 +308,7 @@ public partial class Character : CharacterBody2D, IFaction
         float damage,
         Character inflictor,
         float knockback,
+        Weapon weapon = null,
         Vector2 knockbackDir = default)
     {
         if (Health <= 0)
@@ -352,11 +353,17 @@ public partial class Character : CharacterBody2D, IFaction
             Attacker = inflictor,
             OldHealth = oldHealth,
             NewHealth = Health,
+            Weapon = weapon,
             Damage = damage,
         };
 
         EmitSignal(SignalName.Hurt, args);
 
+        if (inflictor is Player)
+        {
+            EmitPlayerHitSignal(args);
+        }
+
         if (Health <= 0)
         {
             EmitSignal(SignalName.Death, args);
@@ -366,6 +373,25 @@ public partial class Character : CharacterBody2D, IFaction
         }
     }
 
+    /// <summary>
+    /// Converts a HurtArgs to HitArgs if the attacker was a player and emits
+    /// the <c>EventBus.PlayerHit</c> signal.
+    /// </summary>
+    private void EmitPlayerHitSignal(Events.HurtArgs args)
+    {
+        var newArgs = new Events.HitArgs
+        {
+            OldHealth = args.OldHealth,
+            NewHealth = args.NewHealth,
+            Damage = args.Damage,
+            Weapon = args.Weapon,
+            Victim = this,
+        };
+
+        var bus = Events.EventBus.Instance;
+        bus.EmitSignal(Events.EventBus.SignalName.PlayerHit, newArgs);
+    }
+
 #if DEBUG
     /// <summary>
     /// For debugging purposes

Characters/Player.cs

@@ -81,6 +81,7 @@ public sealed partial class Player : Character
         float damage,
         Character inflictor,
         float knockback,
+        Items.Weapon weapon = null,
         Vector2 knockbackDir = default)
     {
         if (damage >= 10 && IsAlive)
@@ -91,7 +92,11 @@ public sealed partial class Player : Character
         GetNode<GpuParticles2D>("Effects/HurtParticles")
             .SetDirection(knockbackDir);
 
-        base.OnReceivedDamage(damage, inflictor, knockback, knockbackDir);
+        base.OnReceivedDamage(damage,
+            inflictor,
+            knockback,
+            weapon,
+            knockbackDir);
     }
 
     public override void Die()

Characters/Player.tscn

@@ -1,12 +1,15 @@
-[gd_scene load_steps=63 format=3 uid="uid://b2254pup8k161"]
+[gd_scene load_steps=66 format=3 uid="uid://b2254pup8k161"]
 
 [ext_resource type="Script" path="res://Characters/Player.cs" id="1_flygr"]
 [ext_resource type="Shader" path="res://Shaders/Flash.gdshader" id="2_ngsgt"]
 [ext_resource type="Texture2D" uid="uid://dpepm54hjuyga" path="res://Assets/Sprites/Characters/forsen-hand.png" id="3_3dqh7"]
 [ext_resource type="Texture2D" uid="uid://bej8thq7ruyty" path="res://Assets/Sprites/Characters/forsen2.png" id="4_5vird"]
+[ext_resource type="Script" path="res://Utils/PlayerStats.cs" id="4_06oya"]
 [ext_resource type="PackedScene" uid="uid://cl56eadpklnbo" path="res://Utils/PlayerCamera.tscn" id="4_ym125"]
 [ext_resource type="Script" path="res://State/Character/CharacterStateMachine.cs" id="5_rgckv"]
+[ext_resource type="Script" path="res://Utils/Values/DoubleValue.cs" id="5_txl0r"]
 [ext_resource type="Script" path="res://State/Character/CharacterDashState.cs" id="6_rft7p"]
+[ext_resource type="Script" path="res://Utils/Values/IntValue.cs" id="6_sunc5"]
 [ext_resource type="Script" path="res://State/Character/PlayerIdleState.cs" id="6_wkfdm"]
 [ext_resource type="PackedScene" uid="uid://dvqap2uhcah63" path="res://Items/Weapons/Sword.tscn" id="7_4rxuv"]
 [ext_resource type="Script" path="res://State/Character/PlayerMoveState.cs" id="7_dfqd8"]
@@ -331,6 +334,15 @@ StateMachine = NodePath("StateMachine")
 Hurtbox = NodePath("Hurtbox")
 Faction = 1
 
+[node name="Stats" type="Node" parent="."]
+script = ExtResource("4_06oya")
+
+[node name="XP" type="Node" parent="Stats"]
+script = ExtResource("5_txl0r")
+
+[node name="Level" type="Node" parent="Stats"]
+script = ExtResource("6_sunc5")
+
 [node name="StateMachine" type="Node" parent="." node_paths=PackedStringArray("InitialState", "Character")]
 script = ExtResource("5_rgckv")
 InitialState = NodePath("Idle")

Entities/Projectile.cs

@@ -43,8 +43,11 @@ public partial class Projectile : RigidBody2D
     [Export]
     public double Delay { get; set; } = 0;
 
+    [System.Obsolete]
     public Character Character { get; set; }
 
+    public Items.Weapon Weapon { get; set; }
+
     public bool IsDead { get; set; }
 
     public override void _Ready()
@@ -87,8 +90,9 @@ public partial class Projectile : RigidBody2D
         {
             hurtbox.InflictDamage(
                 Hitbox.Damage,
-                Character,
+                Hitbox.Inflictor,
                 Hitbox.Knockback,
+                weapon: Weapon,
                 knockbackVector: Direction
             );
             EmitSignal(SignalName.Hit, box);

Entities/ShungiteSpike.cs

@@ -63,6 +63,7 @@ public partial class ShungiteSpike : Projectile
         float damage,
         Characters.Character inflictor,
         float knockback,
+        Items.Weapon weapon,
         Vector2 knockbackDir)
     {
         // if we were hit by the player before the spike freezes,

Events/EventBus.cs

@@ -4,6 +4,8 @@ namespace SupaLidlGame.Events;
 
 public partial class EventBus : Node
 {
+    public static EventBus Instance { get; private set; }
+
     [Signal]
     public delegate void RequestMoveToAreaEventHandler(RequestAreaArgs args);
 
@@ -16,6 +18,15 @@ public partial class EventBus : Node
     [Signal]
     public delegate void PlayerHurtEventHandler(HurtArgs args);
 
+    [Signal]
+    public delegate void PlayerHitEventHandler(HitArgs args);
+
+    [Signal]
+    public delegate void PlayerXPChangedEventHandler(double xp);
+
+    [Signal]
+    public delegate void PlayerLevelChangedEventHandler(int level);
+
     [Signal]
     public delegate void PlayerHealthChangedEventHandler(HealthChangedArgs args);
 
@@ -37,5 +48,10 @@ public partial class EventBus : Node
     public override void _Ready()
     {
         ProcessMode = ProcessModeEnum.Always;
+        if (Instance is not null)
+        {
+            throw new MultipleSingletonsException();
+        }
+        Instance = this;
     }
 }

Events/HitArgs.cs

@@ -0,0 +1,6 @@
+namespace SupaLidlGame.Events;
+
+public partial class HitArgs : HurtArgs
+{
+    public Characters.Character Victim { get; set; }
+}

Exceptions/MultipleSingletonsException.cs

@@ -0,0 +1,6 @@
+namespace SupaLidlGame;
+
+public class MultipleSingletonsException : System.Exception
+{
+
+}

Items/Weapon.cs

@@ -60,6 +60,9 @@ public abstract partial class Weapon : Item
     [Export]
     public float MaxDistanceHint { get; set; }
 
+    [Export]
+    public float PlayerLevelGain { get; set; }
+
     [Export]
     public Sprite2D HandAnchor { get; set; }
 

Items/Weapons/ProjectileSpawner.cs

@@ -49,6 +49,9 @@ public partial class ProjectileSpawner : Ranged
             }
         }
 
+        projectile.Hitbox.Inflictor = Character;
+        projectile.Weapon = this;
+
         if (projectile is Utils.ITarget target)
         {
             if (Character is Characters.NPC npc)

Items/Weapons/Pugio.tscn

@@ -370,35 +370,53 @@ shader_parameter/color = Quaternion(1, 1, 1, 1)
 shader_parameter/intensity = 0.0
 shader_parameter/alpha_modulate = 1.0
 
-[node name="Pugio" type="Node2D"]
+[node name="Pugio" type="Node2D" node_paths=PackedStringArray("Hitbox", "AnimationPlayer", "ParryParticles", "StateMachine", "Anchor", "HandAnchor")]
 y_sort_enabled = true
 texture_filter = 3
 script = ExtResource("1_mai31")
+Hitbox = NodePath("Hitbox")
+AnimationPlayer = NodePath("AnimationPlayer")
 AttackTime = 0.2
 AttackAltTime = 0.75
 AttackAnimationDuration = 0.5
+ParryParticles = NodePath("Anchor/Node2D/Sprite2D/ParryParticles")
 NPCAnticipateTime = 0.3
+StateMachine = NodePath("State")
+Anchor = NodePath("Anchor")
 Damage = 20.0
 UseTime = 0.55
 UseAltTime = 1.5
 Knockback = 64.0
+PlayerLevelGain = 1.0
+HandAnchor = NodePath("Anchor/Node2D/Sprite2D/Hand")
 
-[node name="State" type="Node" parent="."]
+[node name="State" type="Node" parent="." node_paths=PackedStringArray("InitialState")]
 script = ExtResource("2_5ramr")
+InitialState = NodePath("Idle")
 UsedItemStates = Array[NodePath]([NodePath("Attack"), NodePath("Block")])
 DeusedItemStates = Array[NodePath]([NodePath("Idle")])
 
-[node name="Idle" type="Node" parent="State"]
+[node name="Idle" type="Node" parent="State" node_paths=PackedStringArray("UseState", "UseAltState", "Sword")]
 script = ExtResource("3_fwkit")
+UseState = NodePath("../Anticipate")
+UseAltState = NodePath("../Block")
+Sword = NodePath("../..")
 
-[node name="Anticipate" type="Node" parent="State"]
+[node name="Anticipate" type="Node" parent="State" node_paths=PackedStringArray("Sword", "AttackState")]
 script = ExtResource("4_nsn1q")
+Sword = NodePath("../..")
+AttackState = NodePath("../Attack")
 
-[node name="Attack" type="Node" parent="State"]
+[node name="Attack" type="Node" parent="State" node_paths=PackedStringArray("Sword", "IdleState")]
 script = ExtResource("5_g1en5")
+Sword = NodePath("../..")
+IdleState = NodePath("../Idle")
 
-[node name="Block" type="Node" parent="State"]
+[node name="Block" type="Node" parent="State" node_paths=PackedStringArray("Sword", "IdleState", "UseState")]
 script = ExtResource("6_yvm8x")
+Sword = NodePath("../..")
+IdleState = NodePath("../Idle")
+UseState = NodePath("../Anticipate")
 BlockAnimKey = "block"
 
 [node name="WorldEnvironment" type="WorldEnvironment" parent="."]

Items/Weapons/Shotgun.tscn

@@ -258,6 +258,7 @@ StateMachine = NodePath("State")
 Damage = 12.0
 UseTime = 1.5
 InitialVelocity = 220.0
+PlayerLevelGain = 0.5
 
 [node name="State" type="Node" parent="." node_paths=PackedStringArray("InitialState")]
 script = ExtResource("2_ag6rd")

Items/Weapons/Sword.cs

@@ -191,7 +191,11 @@ public partial class Sword : Weapon, IParryable
         {
             if (box is Hurtbox hurtbox)
             {
-                hurtbox.InflictDamage(Damage, Character, Knockback);
+                hurtbox.InflictDamage(
+                    Damage,
+                    Character,
+                    Knockback,
+                    this);
             }
         }
     }

Items/Weapons/Sword.tscn

@@ -354,31 +354,45 @@ graph_offset = Vector2(0, -104.073)
 
 [sub_resource type="AnimationNodeStateMachinePlayback" id="AnimationNodeStateMachinePlayback_37556"]
 
-[node name="Sword" type="Node2D"]
+[node name="Sword" type="Node2D" node_paths=PackedStringArray("Hitbox", "AnimationPlayer", "ParryParticles", "StateMachine", "Anchor", "HandAnchor")]
 y_sort_enabled = true
 texture_filter = 3
 script = ExtResource("1_mlo73")
+Hitbox = NodePath("Hitbox")
+AnimationPlayer = NodePath("AnimationPlayer")
 AttackTime = 0.2
 AttackAnimationDuration = 0.75
+ParryParticles = NodePath("Anchor/Node2D/Sprite2D/ParryParticles")
 NPCAnticipateTime = 0.3
+StateMachine = NodePath("State")
+Anchor = NodePath("Anchor")
 Damage = 20.0
 UseTime = 0.55
 Knockback = 64.0
 ShouldHideIdle = true
+PlayerLevelGain = 1.0
+HandAnchor = NodePath("Anchor/Node2D/Sprite2D/Hand")
 
-[node name="State" type="Node" parent="."]
+[node name="State" type="Node" parent="." node_paths=PackedStringArray("InitialState")]
 script = ExtResource("2_vwirq")
+InitialState = NodePath("Idle")
 UsedItemStates = Array[NodePath]([NodePath("Attack")])
 DeusedItemStates = Array[NodePath]([NodePath("Idle")])
 
-[node name="Idle" type="Node" parent="State"]
+[node name="Idle" type="Node" parent="State" node_paths=PackedStringArray("UseState", "Sword")]
 script = ExtResource("3_nw6r0")
+UseState = NodePath("../Anticipate")
+Sword = NodePath("../..")
 
-[node name="Anticipate" type="Node" parent="State"]
+[node name="Anticipate" type="Node" parent="State" node_paths=PackedStringArray("Sword", "AttackState")]
 script = ExtResource("4_j3cud")
+Sword = NodePath("../..")
+AttackState = NodePath("../Attack")
 
-[node name="Attack" type="Node" parent="State"]
+[node name="Attack" type="Node" parent="State" node_paths=PackedStringArray("Sword", "IdleState")]
 script = ExtResource("5_hmisb")
+Sword = NodePath("../..")
+IdleState = NodePath("../Idle")
 
 [node name="WorldEnvironment" type="WorldEnvironment" parent="."]
 environment = SubResource("Environment_72txp")

UI/Base.tscn

@@ -1,9 +1,10 @@
-[gd_scene load_steps=7 format=3 uid="uid://c271rdjhd1gfo"]
+[gd_scene load_steps=8 format=3 uid="uid://c271rdjhd1gfo"]
 
 [ext_resource type="PackedScene" uid="uid://73jm5qjy52vq" path="res://Dialogue/balloon.tscn" id="1_atjb1"]
 [ext_resource type="Script" path="res://UI/UIController.cs" id="2_b4b6l"]
 [ext_resource type="PackedScene" uid="uid://bxo553hblp6nf" path="res://UI/HealthBar.tscn" id="3_j1j6h"]
 [ext_resource type="PackedScene" uid="uid://01d24ij5av1y" path="res://UI/BossBar.tscn" id="4_igi28"]
+[ext_resource type="PackedScene" uid="uid://cr7tkxctmyags" path="res://UI/LevelBar.tscn" id="4_rcekd"]
 [ext_resource type="PackedScene" uid="uid://c77754nvmckn" path="res://UI/LocationDisplay.tscn" id="5_cr6vo"]
 [ext_resource type="PackedScene" uid="uid://d3q1yu3n7cqfj" path="res://UI/SceneTransition.tscn" id="6_j0nhv"]
 
@@ -47,7 +48,7 @@ BossBar = NodePath("Bottom/BossBar")
 layout_mode = 1
 anchors_preset = 10
 anchor_right = 1.0
-offset_bottom = 40.0
+offset_bottom = 64.0
 grow_horizontal = 2
 
 [node name="Margin" type="MarginContainer" parent="SubViewportContainer/UIViewport/MainUILayer/Main/Top"]
@@ -55,9 +56,21 @@ layout_mode = 2
 theme_override_constants/margin_left = 16
 theme_override_constants/margin_top = 16
 
-[node name="HealthBar" parent="SubViewportContainer/UIViewport/MainUILayer/Main/Top/Margin" instance=ExtResource("3_j1j6h")]
+[node name="VBoxContainer" type="VBoxContainer" parent="SubViewportContainer/UIViewport/MainUILayer/Main/Top/Margin"]
 layout_mode = 2
-size_flags_horizontal = 3
+theme_override_constants/separation = 12
+
+[node name="HealthBar" parent="SubViewportContainer/UIViewport/MainUILayer/Main/Top/Margin/VBoxContainer" instance=ExtResource("3_j1j6h")]
+layout_mode = 2
+
+[node name="LevelBar" parent="SubViewportContainer/UIViewport/MainUILayer/Main/Top/Margin/VBoxContainer" instance=ExtResource("4_rcekd")]
+layout_mode = 2
+
+[node name="Margin2" type="MarginContainer" parent="SubViewportContainer/UIViewport/MainUILayer/Main/Top/Margin/VBoxContainer"]
+visible = false
+layout_mode = 2
+theme_override_constants/margin_left = 16
+theme_override_constants/margin_top = 16
 
 [node name="Bottom" type="HBoxContainer" parent="SubViewportContainer/UIViewport/MainUILayer/Main"]
 layout_mode = 1

UI/LevelBar.cs

@@ -0,0 +1,36 @@
+using Godot;
+using SupaLidlGame.Events;
+
+namespace SupaLidlGame.UI;
+
+public partial class LevelBar : Control
+{
+    public TextureProgressBar XPBar { get; set; }
+
+    private TextureProgressBar[] _levelBars = new TextureProgressBar[4];
+
+    public override void _Ready()
+    {
+        XPBar = GetNode<TextureProgressBar>("%XPBar");
+
+        for (int i = 0; i < 4; i++)
+        {
+            _levelBars[i] = GetNode<TextureProgressBar>($"%Level{i + 1}Bar");
+        }
+
+        EventBus.Instance.PlayerXPChanged += (xp) =>
+        {
+            XPBar.Value = xp;
+        };
+
+        EventBus.Instance.PlayerLevelChanged += (level) =>
+        {
+            for (int i = 0; i < _levelBars.Length; i++)
+            {
+                // level 0: 0 is not less than 0
+                // level 1: 0 is less than 1
+                _levelBars[i].Value = i < level ? 1 : 0;
+            }
+        };
+    }
+}

UI/LevelBar.tscn

@@ -0,0 +1,94 @@
+[gd_scene load_steps=4 format=3 uid="uid://cr7tkxctmyags"]
+
+[ext_resource type="Script" path="res://UI/LevelBar.cs" id="1_eqetx"]
+[ext_resource type="Texture2D" uid="uid://b75oak1nd2q6x" path="res://Assets/Sprites/UI/over-under-bar.png" id="2_f332l"]
+[ext_resource type="Texture2D" uid="uid://co7xm7i5f6n51" path="res://Assets/Sprites/UI/progress-bar.png" id="3_arvub"]
+
+[node name="LevelBar" type="Control"]
+layout_mode = 3
+anchors_preset = 0
+offset_right = 128.0
+offset_bottom = 8.0
+script = ExtResource("1_eqetx")
+
+[node name="HBoxContainer" type="HBoxContainer" parent="."]
+layout_mode = 2
+offset_right = 128.0
+offset_bottom = 8.0
+
+[node name="XPBar" type="TextureProgressBar" parent="HBoxContainer"]
+unique_name_in_owner = true
+texture_filter = 1
+layout_mode = 2
+size_flags_horizontal = 3
+max_value = 4.0
+step = 0.01
+nine_patch_stretch = true
+stretch_margin_left = 3
+stretch_margin_top = 3
+stretch_margin_right = 3
+stretch_margin_bottom = 3
+texture_under = ExtResource("2_f332l")
+texture_progress = ExtResource("3_arvub")
+
+[node name="Level1Bar" type="TextureProgressBar" parent="HBoxContainer"]
+unique_name_in_owner = true
+texture_filter = 1
+layout_mode = 2
+max_value = 1.0
+nine_patch_stretch = true
+stretch_margin_left = 3
+stretch_margin_top = 3
+stretch_margin_right = 3
+stretch_margin_bottom = 3
+texture_under = ExtResource("2_f332l")
+texture_progress = ExtResource("3_arvub")
+
+[node name="Level2Bar" type="TextureProgressBar" parent="HBoxContainer"]
+unique_name_in_owner = true
+texture_filter = 1
+layout_mode = 2
+max_value = 1.0
+nine_patch_stretch = true
+stretch_margin_left = 3
+stretch_margin_top = 3
+stretch_margin_right = 3
+stretch_margin_bottom = 3
+texture_under = ExtResource("2_f332l")
+texture_progress = ExtResource("3_arvub")
+
+[node name="Level3Bar" type="TextureProgressBar" parent="HBoxContainer"]
+unique_name_in_owner = true
+texture_filter = 1
+layout_mode = 2
+max_value = 1.0
+nine_patch_stretch = true
+stretch_margin_left = 3
+stretch_margin_top = 3
+stretch_margin_right = 3
+stretch_margin_bottom = 3
+texture_under = ExtResource("2_f332l")
+texture_progress = ExtResource("3_arvub")
+
+[node name="Level4Bar" type="TextureProgressBar" parent="HBoxContainer"]
+unique_name_in_owner = true
+texture_filter = 1
+layout_mode = 2
+max_value = 1.0
+nine_patch_stretch = true
+stretch_margin_left = 3
+stretch_margin_top = 3
+stretch_margin_right = 3
+stretch_margin_bottom = 3
+texture_under = ExtResource("2_f332l")
+texture_progress = ExtResource("3_arvub")
+
+[node name="VBoxContainer" type="VBoxContainer" parent="."]
+visible = false
+layout_mode = 1
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+theme_override_constants/separation = 4

Utils/PlayerStats.cs

@@ -0,0 +1,75 @@
+using Godot;
+using SupaLidlGame.Events;
+
+namespace SupaLidlGame.Utils;
+
+public partial class PlayerStats : Node
+{
+    public const int MAX_XP_PER_LEVEL = 4;
+
+    public const int MAX_LEVELS = 4;
+
+    public DoubleValue XP { get; set; }
+
+    public IntValue Level { get; set; }
+
+    public double XPDecayVelocity { get; set; } = 1;
+
+    protected bool _shouldDecayXP = true;
+
+    protected Timer _xpDecayTimer;
+
+    public override void _Ready()
+    {
+        XP = GetNode<DoubleValue>("XP");
+        Level = GetNode<IntValue>("Level");
+
+        _xpDecayTimer = new Timer();
+        _xpDecayTimer.Timeout += () => _shouldDecayXP = true;
+        _xpDecayTimer.Stop();
+        AddChild(_xpDecayTimer);
+
+        var bus = EventBus.Instance;
+        XP.Changed += (oldValue, newValue) =>
+        {
+            bus.EmitSignal(EventBus.SignalName.PlayerXPChanged, newValue);
+        };
+
+        Level.Changed += (oldValue, newValue) =>
+        {
+            bus.EmitSignal(EventBus.SignalName.PlayerLevelChanged, newValue);
+        };
+
+        bus.PlayerHit += (args) =>
+        {
+            double xp = XP.Value;
+            xp += args.Weapon?.PlayerLevelGain ?? 0;
+
+            if (xp >= MAX_XP_PER_LEVEL)
+            {
+                int deltaLevel = (int)(xp / MAX_XP_PER_LEVEL);
+                xp %= MAX_XP_PER_LEVEL;
+                Level.Value = Mathf.Min(Level.Value + deltaLevel, MAX_LEVELS);
+            }
+
+            if (Level.Value == MAX_LEVELS)
+            {
+                // if max level, can only go up to 1 xp
+                xp = Mathf.Min(xp, 1);
+            }
+
+            XP.Value = xp;
+
+            _shouldDecayXP = false;
+            _xpDecayTimer.Start(1);
+        };
+    }
+
+    public override void _Process(double delta)
+    {
+        if (_shouldDecayXP)
+        {
+            XP.Value = Mathf.MoveToward(XP.Value, 1, XPDecayVelocity * delta);
+        }
+    }
+}

Utils/Values/DoubleValue.cs

@@ -0,0 +1,22 @@
+using Godot;
+
+namespace SupaLidlGame;
+
+public partial class DoubleValue : Node, IValue<double>
+{
+    [Signal]
+    public delegate void ChangedEventHandler(double oldValue, double newValue);
+
+    protected double _value = default;
+
+    [Export]
+    public double Value
+    {
+        get => _value;
+        set
+        {
+            EmitSignal(SignalName.Changed, _value, value);
+            _value = value;
+        }
+    }
+}

Utils/Values/FloatValue.cs

@@ -0,0 +1,22 @@
+using Godot;
+
+namespace SupaLidlGame;
+
+public partial class FloatValue : Node, IValue<float>
+{
+    [Signal]
+    public delegate void ChangedEventHandler(float oldValue, float newValue);
+
+    protected float _value = default;
+
+    [Export]
+    public float Value
+    {
+        get => _value;
+        set
+        {
+            EmitSignal(SignalName.Changed, _value, value);
+            _value = value;
+        }
+    }
+}

Utils/Values/IValue.cs

@@ -0,0 +1,8 @@
+namespace SupaLidlGame;
+
+public interface IValue<T>
+{
+    public delegate void ChangedEventHandler(T oldValue, T newValue);
+
+    public T Value { get; set; }
+}

Utils/Values/IntValue.cs

@@ -0,0 +1,22 @@
+using Godot;
+
+namespace SupaLidlGame;
+
+public partial class IntValue : Node, IValue<int>
+{
+    [Signal]
+    public delegate void ChangedEventHandler(int oldValue, int newValue);
+
+    protected int _value = default;
+
+    [Export]
+    public int Value
+    {
+        get => _value;
+        set
+        {
+            EmitSignal(SignalName.Changed, _value, value);
+            _value = value;
+        }
+    }
+}