Simple knockback implementation

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

@@ -44,6 +44,8 @@ public partial class NavigationMovementModule : Node2D
         var nextPathPosition = _navigationAgent.GetNextPathPosition();
 
         var newVelocity = currentAgentPosition.DirectionTo(nextPathPosition) * movementSpeed;
+
+        newVelocity += StorageModule.KnockbackVelocity;
         
         if (_navigationAgent.AvoidanceEnabled)
         {