Collision Bug Test

project.godot ################################################################################################
; Engine configuration file.
; It's best edited using the editor UI and not directly,
; since the parameters that go here are not all obvious.
;
; Format:
;   [section] ; section goes between []
;   param=value ; assign values to parameters

config_version=5

[application]

config/name="CollisionBugTest"
run/main_scene="uid://chiiwry3l2pkm"
config/features=PackedStringArray("4.7", "C#", "Mobile")
config/icon="res://icon.svg"

[autoload]

EnemyObjectPool="*uid://dkifioyg6eets"

[display]

window/size/viewport_width=640
window/size/viewport_height=360
window/stretch/mode="viewport"
window/stretch/scale_mode="integer"

[dotnet]

project/assembly_name="CollisionBugTest"

[layer_names]

2d_physics/layer_1="Player"
2d_physics/layer_2="Enemy"

[physics]

3d/physics_engine="Jolt Physics"

[rendering]

rendering_device/driver.windows="d3d12"
renderer/rendering_method="mobile"

PlayableArea.cs ################################################################################################
using Godot;
using System;

public partial class PlayableArea : Area2D
{
    public override void _Ready()
    {
        BodyEntered += OnBodyEntered;
        BodyExited += OnBodyExited;
    }

    private void OnBodyEntered(Node2D body)
    {
        if (body is Enemy)
            GD.Print($"[Playable area] Enemy entered");
    }

    private async void OnBodyExited(Node2D body)
    {
        try
        {
            if (body is Enemy enemy)
            {
                GD.Print("[Playable area] Enemy left.");
                await enemy.DefeatAsync(); //you would remove enemy here without full animated sequence but for minimal example it's okay
            }
        }
        catch (Exception e)
        {
            GD.PrintErr(e);
        }
    }
}

Game.cs ################################################################################################
using Godot;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

public partial class Game : Node2D
{
    [Export] private Button _btnStart;
    [Export] private Button _btnKill;

    private EnemyObjectPool _objectPool;

    private List<Enemy> _spawnedEnemies;

    private bool _started = false;
    private bool _killed = false;

    public override void _Ready()
    {
        base._Ready();
        _objectPool = EnemyObjectPool.Instance;
        _spawnedEnemies = [];

        _btnStart.Pressed += OnButtonStartPressed;
        _btnKill.Pressed += OnButtonKillPressed;

        _btnKill.Disabled = true;

        GD.Print($"[Game] Ready \n");
    }

    private async Task SpawnAsync()
    {
        GD.Print("[Game] Starting spawn sequence");
        var enemy = _objectPool.Dequeue();
        _spawnedEnemies.Add(enemy);
        enemy.Enable(new Vector2(512, 102));

        var position = new Vector2(64, 102);

        Tween tween = CreateTween();
        tween.SetEase(Tween.EaseType.Out);
        tween.SetTrans(Tween.TransitionType.Linear);
        tween.TweenProperty(enemy, "global_position", position, 2.0);
        await ToSignal(tween, Tween.SignalName.Finished);
        enemy.ReachedDesignatedLocation = true;
        GD.Print("\n");
    }

    private async Task DestroyEnemyAsync()
    {
        GD.Print($"[Game] Enemy defeated by player request.");
        var enemy = _spawnedEnemies.FirstOrDefault();
        if (enemy != null && enemy.ReachedDesignatedLocation)
        {
            await enemy.DefeatAsync();
            _spawnedEnemies.Remove(enemy);
        }
        GD.Print($"\n");
    }

    #region controls

    private async void OnButtonStartPressed()
    {
        try
        {
            _btnStart.Disabled = true;

            await SpawnAsync();

            _btnKill.Disabled = false;
        }
        catch (Exception e)
        {
            GD.PrintErr(e);
        }
    }

    private async void OnButtonKillPressed()
    {
        try
        {
            _btnKill.Disabled = true;

            await DestroyEnemyAsync();

            await SpawnAsync();
        }
        catch (Exception e)
        {
            GD.PrintErr(e);
        }
    }

    #endregion
}

EnemyObjectPool.cs ################################################################################################
using Godot;
using System;
using System.Collections.Generic;

public partial class EnemyObjectPool : Node
{
    public static EnemyObjectPool Instance { get; private set; }

    [Export] private PackedScene _enemy;

    private int _maxMobs = 1;
    private Queue<Enemy> _objectPool;

    public override void _Ready()
    {
        Instance = this;

        var currentScene = GetTree()?.CurrentScene;
        var enemyContainer = currentScene.GetNode<Node2D>("EnemyContainer");
        InitializeEnemy(enemyContainer);
        GD.Print("[Object pool] Ready");
    }

    private void InitializeEnemy(Node2D container)
    {
        _objectPool = new();
        for (int i = 0; i < _maxMobs; i++)
        {
            var instance = _enemy.Instantiate() as Enemy;
            instance.Defeated += Enqueue;
            _objectPool.Enqueue(instance);
            container.AddChild(instance);
        }
    }
    private void Enqueue(Enemy enemy)
    {
        GD.Print("[Object pool] Enqueue");
        _objectPool.Enqueue(enemy);
        if (_objectPool.Count > _maxMobs) GD.PrintErr("Object pool size exceeded.");
    }

    public Enemy Dequeue()
    {
        GD.Print("[Object pool] Dequeue");
        return _objectPool.Dequeue();
    }
}

Enemy.cs ################################################################################################
using Godot;
using System;
using System.Threading.Tasks;

public partial class Enemy : CharacterBody2D
{
    [Export] private CollisionShape2D _collision;

    public event Action<Enemy> Defeated;
    public bool ReachedDesignatedLocation { get; set; }

    private Vector2 _storagePoint = new(608, 90);
    private int _direction = 1;
    private bool _defeated = false;

    public void InvokeDefeated()
    {
        Defeated?.Invoke(this);
    }

    public override void _Ready()
    {
        base._Ready();
        Disable();
        GD.Print("[Enemy] Ready");
    }

    public override void _PhysicsProcess(double delta)
    {
        base._PhysicsProcess(delta);

        if(!ReachedDesignatedLocation) return;

        _direction *= -1;
        GlobalPosition += new Vector2(5 * _direction, 0);
    }

    public void Enable(Vector2 position)
    {
        GD.Print("[Enemy] Enable");
        _defeated = false;
        SetPhysicsProcess(true);
        GlobalPosition = position;
        _collision.SetDeferred(CollisionShape2D.PropertyName.Disabled, false);
    }

    public async Task DefeatAsync()
    {
        if(_defeated) return;
        _defeated = true;

        GD.Print("[Enemy] Defeat");

        StopProcessing();
        await SimulateDefeatAnimationAsync();
        MoveToStoragePoint();
        InvokeDefeated();
        //not hiding the sprite to see where the guy actually is
    }

    private async Task SimulateDefeatAnimationAsync()
    {
        Tween tween = CreateTween();
        tween.TweenProperty(this, "rotation_degrees", RotationDegrees + 360, 1.0f);
        await ToSignal(tween, Tween.SignalName.Finished);
    }

    private void StopProcessing()
    {
        _collision.SetDeferred(CollisionShape2D.PropertyName.Disabled, true);
        SetPhysicsProcess(false);
    }

    private void Disable()
    {
        StopProcessing();
        MoveToStoragePoint();
    }

    private void MoveToStoragePoint()
    {
        GlobalPosition = _storagePoint;
    }
}

enemy_object_pool.tscn ################################################################################################
[gd_scene format=3 uid="uid://dkifioyg6eets"]

[ext_resource type="Script" uid="uid://b3k174bgmq0lm" path="res://EnemyObjectPool.cs" id="1_0mxj6"]
[ext_resource type="PackedScene" uid="uid://bxjv371c24hv6" path="res://enemy.tscn" id="2_omt7x"]

[node name="EnemyObjectPool" type="Node" unique_id=1887825628]
script = ExtResource("1_0mxj6")
_enemy = ExtResource("2_omt7x")

enemy.tscn ################################################################################################
[gd_scene format=3 uid="uid://bxjv371c24hv6"]

[ext_resource type="Script" uid="uid://cqilqfy20e3fw" path="res://Enemy.cs" id="1_7k104"]

[sub_resource type="Gradient" id="Gradient_7xaro"]

[sub_resource type="GradientTexture2D" id="GradientTexture2D_plrnn"]
gradient = SubResource("Gradient_7xaro")
fill = 1
fill_from = Vector2(0.51304346, 0.5)

[sub_resource type="RectangleShape2D" id="RectangleShape2D_7xaro"]
size = Vector2(64, 64)

[node name="Enemy" type="CharacterBody2D" unique_id=1267955304 node_paths=PackedStringArray("_collision")]
collision_layer = 2
script = ExtResource("1_7k104")
_collision = NodePath("CollisionShape2D")

[node name="Sprite2D" type="Sprite2D" parent="." unique_id=1626383384]
texture = SubResource("GradientTexture2D_plrnn")

[node name="CollisionShape2D" type="CollisionShape2D" parent="." unique_id=1732114049]
shape = SubResource("RectangleShape2D_7xaro")

game.tscn ################################################################################################
[gd_scene format=3 uid="uid://chiiwry3l2pkm"]

[ext_resource type="Script" uid="uid://ce2yo6xexi7a6" path="res://Game.cs" id="1_80nbo"]
[ext_resource type="Script" uid="uid://cov46dvwceotm" path="res://PlayableArea.cs" id="2_e2o6t"]

[sub_resource type="RectangleShape2D" id="RectangleShape2D_plrnn"]
size = Vector2(320, 360)

[node name="Game" type="Node2D" unique_id=325719013 node_paths=PackedStringArray("_btnStart", "_btnKill")]
script = ExtResource("1_80nbo")
_btnStart = NodePath("Button")
_btnKill = NodePath("Button2")

[node name="Camera2D" type="Camera2D" parent="." unique_id=540720120]
position = Vector2(320, 176)

[node name="PlayableArea" type="Area2D" parent="." unique_id=467738821]
collision_layer = 0
collision_mask = 2
script = ExtResource("2_e2o6t")

[node name="CollisionShape2D" type="CollisionShape2D" parent="PlayableArea" unique_id=577274571]
position = Vector2(160, 180)
shape = SubResource("RectangleShape2D_plrnn")

[node name="EnemyContainer" type="Node2D" parent="." unique_id=1525994715]

[node name="Button" type="Button" parent="." unique_id=1855880708]
offset_left = 328.0
offset_top = 240.0
offset_right = 384.0
offset_bottom = 271.0
text = "START"

[node name="Button2" type="Button" parent="." unique_id=1367707068]
offset_left = 328.0
offset_top = 280.0
offset_right = 369.0
offset_bottom = 311.0
text = "KILL & RESPAWN"