Simple knockback implementation

Resources/Bullets/icicle_gun_bullets.tres

@@ -11,6 +11,7 @@ DestructionParticlesScene = ExtResource("2_04tom")
 BulletSpeed = 300.0
 Direction = Vector2(1, 0)
 BulletDamage = 0.4
+Knockback = 100.0
 LifeTime = 10.0
 DestroyOnCollision = true
 Owner = 1

Scenes/Actors/Fairy_FSM.tscn

@@ -1,4 +1,4 @@
-[gd_scene load_steps=35 format=3 uid="uid://clieeuln36a7a"]
+[gd_scene load_steps=36 format=3 uid="uid://clieeuln36a7a"]
 
 [ext_resource type="Script" uid="uid://dn6dbog1s2818" path="res://Scripts/Components/FSM/Enemy/EnemyStateMachine.cs" id="1_27djw"]
 [ext_resource type="SpriteFrames" uid="uid://bcc5mlwwnkvri" path="res://Resources/Sprites/Fairy.tres" id="1_ho0th"]
@@ -25,6 +25,7 @@
 [ext_resource type="Script" uid="uid://dq338w2lw5phl" path="res://Scripts/Components/Actors/KeyboardInputProvider.cs" id="24_f3gn5"]
 [ext_resource type="Texture2D" uid="uid://b2v6j7lsyltrc" path="res://Sprites/Actors/CirnoWings.png" id="25_hnfyq"]
 [ext_resource type="Script" uid="uid://d208gvthkstvc" path="res://Scripts/Components/Actors/PlayerCrosshairProvider.cs" id="26_hnfyq"]
+[ext_resource type="Script" uid="uid://by1w0oo6nguyv" path="res://Scripts/Components/FSM/Enemy/EnemyKnockbackProvider.cs" id="27_hnfyq"]
 [ext_resource type="Texture2D" uid="uid://cf2855sd3hqty" path="res://Sprites/Actors/Aiming_Reticule_Small.png" id="27_wafqr"]
 
 [sub_resource type="CircleShape2D" id="CircleShape2D_pnkma"]
@@ -97,7 +98,7 @@ script = ExtResource("4_kjmts")
 StorageModule = NodePath("../../Storage")
 PlayerDetection = NodePath("../../PlayerDetection")
 DamageReceiver = NodePath("../../DamageReceiver")
-_moduleNodes = [NodePath("../../AlarmModule"), NodePath("../../AnimationModule")]
+_moduleNodes = [NodePath("../../AlarmModule"), NodePath("../../AnimationModule"), NodePath("../../Knockbackprovider")]
 
 [node name="Alert" type="Node2D" parent="StateMachine" node_paths=PackedStringArray("StorageModule", "PlayerDetection", "DamageReceiver", "NavigationModule", "_moduleNodes")]
 script = ExtResource("5_f112g")
@@ -105,7 +106,7 @@ StorageModule = NodePath("../../Storage")
 PlayerDetection = NodePath("../../PlayerDetection")
 DamageReceiver = NodePath("../../DamageReceiver")
 NavigationModule = NodePath("../../NavigationModule")
-_moduleNodes = [NodePath("../../AnimationModule")]
+_moduleNodes = [NodePath("../../AnimationModule"), NodePath("../../Knockbackprovider")]
 
 [node name="Shooting" type="Node2D" parent="StateMachine" node_paths=PackedStringArray("StorageModule", "PlayerDetection", "DamageReceiver", "NavigationModule", "EquippedWeapon", "_moduleNodes")]
 script = ExtResource("7_br0mr")
@@ -114,7 +115,7 @@ PlayerDetection = NodePath("../../PlayerDetection")
 DamageReceiver = NodePath("../../DamageReceiver")
 NavigationModule = NodePath("../../NavigationModule")
 EquippedWeapon = NodePath("../../EnemyWeapon")
-_moduleNodes = [NodePath("../../AnimationModule")]
+_moduleNodes = [NodePath("../../AnimationModule"), NodePath("../../Knockbackprovider")]
 
 [node name="Dead" type="Node2D" parent="StateMachine" node_paths=PackedStringArray("StorageModule", "DropsProvider")]
 script = ExtResource("8_pi7ab")
@@ -222,6 +223,11 @@ CrosshairDistance = 35.0
 [node name="Crosshair" type="AnimatedSprite2D" parent="CrosshairProvider"]
 sprite_frames = SubResource("SpriteFrames_biwfl")
 
+[node name="Knockbackprovider" type="Node2D" parent="." node_paths=PackedStringArray("DamageReceiver", "StorageModule")]
+script = ExtResource("27_hnfyq")
+DamageReceiver = NodePath("../DamageReceiver")
+StorageModule = NodePath("../Storage")
+
 [connection signal="area_entered" from="PlayerDetection" to="PlayerDetection" method="_on_area_entered"]
 [connection signal="area_exited" from="PlayerDetection" to="PlayerDetection" method="_on_area_exited"]
 [connection signal="area_entered" from="DamageReceiver" to="DamageReceiver" method="_on_damage_hitbox_area_entered"]

Scenes/Actors/Fairy_Guard_FSM.tscn

@@ -1,4 +1,4 @@
-[gd_scene load_steps=36 format=3 uid="uid://bb32f4p5e671j"]
+[gd_scene load_steps=37 format=3 uid="uid://bb32f4p5e671j"]
 
 [ext_resource type="Script" uid="uid://bi2edpdosngll" path="res://Scripts/Components/FSM/Enemy/EnemyFSMProxy.cs" id="1_514kd"]
 [ext_resource type="Resource" uid="uid://qbo6avc7x64b" path="res://Resources/Enemies/Fairy_Guard.tres" id="2_514kd"]
@@ -27,6 +27,7 @@
 [ext_resource type="Script" uid="uid://dq338w2lw5phl" path="res://Scripts/Components/Actors/KeyboardInputProvider.cs" id="25_5xyu0"]
 [ext_resource type="Script" uid="uid://d208gvthkstvc" path="res://Scripts/Components/Actors/PlayerCrosshairProvider.cs" id="26_u2sah"]
 [ext_resource type="Texture2D" uid="uid://cf2855sd3hqty" path="res://Sprites/Actors/Aiming_Reticule_Small.png" id="27_na4im"]
+[ext_resource type="Script" uid="uid://by1w0oo6nguyv" path="res://Scripts/Components/FSM/Enemy/EnemyKnockbackProvider.cs" id="28_5gayb"]
 
 [sub_resource type="CircleShape2D" id="CircleShape2D_pnkma"]
 
@@ -98,7 +99,7 @@ script = ExtResource("5_xxkf8")
 StorageModule = NodePath("../../Storage")
 PlayerDetection = NodePath("../../PlayerDetection")
 DamageReceiver = NodePath("../../DamageReceiver")
-_moduleNodes = [NodePath("../../AlarmModule"), NodePath("../../AnimationModule")]
+_moduleNodes = [NodePath("../../AlarmModule"), NodePath("../../AnimationModule"), NodePath("../../Knockbackprovider")]
 
 [node name="Alert" type="Node2D" parent="StateMachine" node_paths=PackedStringArray("StorageModule", "PlayerDetection", "DamageReceiver", "NavigationModule", "_moduleNodes")]
 script = ExtResource("6_kji07")
@@ -106,7 +107,7 @@ StorageModule = NodePath("../../Storage")
 PlayerDetection = NodePath("../../PlayerDetection")
 DamageReceiver = NodePath("../../DamageReceiver")
 NavigationModule = NodePath("../../NavigationModule")
-_moduleNodes = [NodePath("../../AnimationModule")]
+_moduleNodes = [NodePath("../../AnimationModule"), NodePath("../../Knockbackprovider")]
 
 [node name="Shooting" type="Node2D" parent="StateMachine" node_paths=PackedStringArray("StorageModule", "PlayerDetection", "DamageReceiver", "NavigationModule", "EquippedWeapon", "_moduleNodes")]
 script = ExtResource("7_w6ssf")
@@ -115,7 +116,7 @@ PlayerDetection = NodePath("../../PlayerDetection")
 DamageReceiver = NodePath("../../DamageReceiver")
 NavigationModule = NodePath("../../NavigationModule")
 EquippedWeapon = NodePath("../../EnemyWeapon")
-_moduleNodes = [NodePath("../../AnimationModule")]
+_moduleNodes = [NodePath("../../AnimationModule"), NodePath("../../Knockbackprovider")]
 
 [node name="Dead" type="Node2D" parent="StateMachine" node_paths=PackedStringArray("StorageModule", "DropsProvider")]
 script = ExtResource("8_8jlfa")
@@ -224,6 +225,11 @@ CrosshairDistance = 35.0
 [node name="Crosshair" type="AnimatedSprite2D" parent="CrosshairProvider"]
 sprite_frames = SubResource("SpriteFrames_biwfl")
 
+[node name="Knockbackprovider" type="Node2D" parent="." node_paths=PackedStringArray("DamageReceiver", "StorageModule")]
+script = ExtResource("28_5gayb")
+DamageReceiver = NodePath("../DamageReceiver")
+StorageModule = NodePath("../Storage")
+
 [connection signal="area_entered" from="PlayerDetection" to="PlayerDetection" method="_on_area_entered"]
 [connection signal="area_exited" from="PlayerDetection" to="PlayerDetection" method="_on_area_exited"]
 [connection signal="area_entered" from="DamageReceiver" to="DamageReceiver" method="_on_damage_hitbox_area_entered"]

Scripts/Components/Actors/GenericDamageReceiver.cs

@@ -23,6 +23,8 @@ public partial class GenericDamageReceiver : Area2D, IHittable
     [Signal]
     public delegate void ShieldHitEventHandler();
     
+    [Signal] public delegate void BulletHitEventHandler(Bullet bullet, Vector2 position, Vector2 direction);
+    
     //[Signal] public delegate void DeathEventHandler();
     
     private Node2D _parent;
@@ -54,6 +56,9 @@ public partial class GenericDamageReceiver : Area2D, IHittable
         if (BulletGroup is BulletOwner.None)
         {
             this.Hit(bullet.Damage, bullet.DamageType);
+            
+            EmitSignalBulletHit(bullet, area.GlobalPosition, (this.GlobalPosition - area.GlobalPosition).Normalized());
+            
             bullet.RequestCollisionDestruction();
             return;
         }
@@ -61,6 +66,9 @@ public partial class GenericDamageReceiver : Area2D, IHittable
         if (bullet.BulletInfo.Owner == BulletGroup) return; 
         
         this.Hit(bullet.Damage, bullet.DamageType);
+        
+        EmitSignalBulletHit(bullet, area.GlobalPosition, (this.GlobalPosition - area.GlobalPosition).Normalized());
+        
         bullet.RequestCollisionDestruction();
     }
     

Scripts/Components/BulletSpawner.cs

@@ -92,6 +92,7 @@ public class BulletInfo
     public BulletOwner Owner { get; set; }
     public DamageType DamageType { get; set; }
     public float Damage { get; set; }
+    public float Knockback { get; set; }
     public int BulletCount { get; set; }
     public float RotationSpeed { get; set; }
     public float RotationOffset { get; set; }

Scripts/Components/FSM/Enemy/EnemyKnockbackProvider.cs

@@ -0,0 +1,60 @@
+using Cirno.Scripts.Components.Actors;
+using Cirno.Scripts.Enums;
+using Godot;
+
+namespace Cirno.Scripts.Components.FSM.Enemy;
+
+public partial class EnemyKnockbackProvider : ModuleBase<EnemyState, CharacterBody2D>
+{
+    [Export] public GenericDamageReceiver DamageReceiver { get; private set; }
+    [Export] public EnemyStorageModule StorageModule { get; private set; }
+    
+    [Export] public float KnockbackDecayRate = 800f; // pixels per second^2, tweak this
+
+    private Vector2 KnockbackVelocity
+    {
+        get => StorageModule.KnockbackVelocity;
+        set => StorageModule.KnockbackVelocity = value;
+    }
+
+    private bool IsKnockbackActive => KnockbackVelocity.LengthSquared() > 1f;
+    
+    private IStateMachine<EnemyState, CharacterBody2D> _machine;
+    private bool _enabled = false;
+    public override void EnterState(EnemyState state)
+    {
+        _enabled = true;
+        DamageReceiver.BulletHit += DamageReceiverOnBulletHit;
+    }
+
+    private void DamageReceiverOnBulletHit(Bullet bullet, Vector2 position, Vector2 direction)
+    {
+        var knockbackVelocity = direction * bullet.BulletInfo.Knockback;
+        
+        KnockbackVelocity = knockbackVelocity;
+    }
+
+    public override void ExitState(EnemyState state)
+    {
+        _enabled = false;
+        DamageReceiver.BulletHit -= DamageReceiverOnBulletHit;
+    }
+
+    public override void Init(IStateMachine<EnemyState, CharacterBody2D> machine)
+    {
+        _machine = machine;
+    }
+
+    public override void Process(double delta)
+    {
+        
+    }
+
+    public override void PhysicsProcess(double delta)
+    {
+        if (IsKnockbackActive)
+        {
+            KnockbackVelocity = KnockbackVelocity.MoveToward(Vector2.Zero, KnockbackDecayRate * (float)delta);
+        }
+    }
+}

Scripts/Components/FSM/Enemy/EnemyKnockbackProvider.cs.uid

@@ -0,0 +1 @@
+uid://by1w0oo6nguyv

Scripts/Components/FSM/Enemy/EnemyStorageModule.cs

@@ -22,6 +22,7 @@ public partial class EnemyStorageModule : Node2D, IFSMStorage
     public Vector2 FacingDirection { get; set; }
     
     public Vector2 AimingDirection { get; set; }
+    public Vector2 KnockbackVelocity { get; set; } = Vector2.Zero;
 
     public float MovementSpeed => Root.EnemyResource.MovementSpeed;
 

Scripts/Components/FSM/Enemy/NavigationMovementModule.cs

@@ -45,6 +45,8 @@ public partial class NavigationMovementModule : Node2D
 
         var newVelocity = currentAgentPosition.DirectionTo(nextPathPosition) * movementSpeed;
 
+        newVelocity += StorageModule.KnockbackVelocity;
+        
         if (_navigationAgent.AvoidanceEnabled)
         {
             _navigationAgent.SetVelocity(newVelocity);

Scripts/Resources/BulletResource.cs

@@ -16,6 +16,7 @@ public partial class BulletResource : Resource
     [Export] public float BulletSpeed = 100f;
     [Export] public Vector2 Direction = Vector2.Right;
     [Export] public float BulletDamage = 1;
+    [Export] public float Knockback = 1;
     [Export] public float LifeTime = 10f;
     [Export] public bool DestroyOnCollision = true;
     [Export] public BulletOwner Owner = BulletOwner.None;
@@ -40,6 +41,7 @@ public partial class BulletResource : Resource
             Owner = Owner,
             DamageType = DamageType,
             Damage = BulletDamage,
+            Knockback = Knockback,
             BulletCount = count,
             Spread = spread,
             BulletScene = BulletScene,