Lag compensation for wide attacks (#15877)

Content.Shared/Weapons/Melee/SharedMeleeWeaponSystem.cs

@@ -41,7 +41,7 @@ public abstract class SharedMeleeWeaponSystem : EntitySystem
     [Dependency] protected readonly SharedInteractionSystem Interaction = default!;
     [Dependency] private   readonly SharedPhysicsSystem _physics = default!;
     [Dependency] protected readonly SharedPopupSystem PopupSystem = default!;
-    [Dependency] protected   readonly SharedTransformSystem _transform = default!;
+    [Dependency] protected readonly SharedTransformSystem _transform = default!;
     [Dependency] private   readonly StaminaSystem _stamina = default!;
 
     protected ISawmill Sawmill = default!;
@@ -65,10 +65,10 @@ public abstract class SharedMeleeWeaponSystem : EntitySystem
         SubscribeLocalEvent<MeleeWeaponComponent, HandDeselectedEvent>(OnMeleeDropped);
         SubscribeLocalEvent<MeleeWeaponComponent, HandSelectedEvent>(OnMeleeSelected);
 
+        SubscribeAllEvent<HeavyAttackEvent>(OnHeavyAttack);
         SubscribeAllEvent<LightAttackEvent>(OnLightAttack);
         SubscribeAllEvent<StartHeavyAttackEvent>(OnStartHeavyAttack);
         SubscribeAllEvent<StopHeavyAttackEvent>(OnStopHeavyAttack);
-        SubscribeAllEvent<HeavyAttackEvent>(OnHeavyAttack);
         SubscribeAllEvent<DisarmAttackEvent>(OnDisarmAttack);
         SubscribeAllEvent<StopAttackEvent>(OnStopAttack);
 
@@ -513,29 +513,23 @@ public abstract class SharedMeleeWeaponSystem : EntitySystem
 
     protected abstract void DoDamageEffect(List<EntityUid> targets, EntityUid? user,  TransformComponent targetXform);
 
-    protected virtual void DoHeavyAttack(EntityUid user, HeavyAttackEvent ev, EntityUid meleeUid, MeleeWeaponComponent component, ICommonSession? session)
+    private void DoHeavyAttack(EntityUid user, HeavyAttackEvent ev, EntityUid meleeUid, MeleeWeaponComponent component, ICommonSession? session)
     {
         // TODO: This is copy-paste as fuck with DoPreciseAttack
         if (!TryComp<TransformComponent>(user, out var userXform))
-        {
             return;
-        }
 
         var targetMap = ev.Coordinates.ToMap(EntityManager, _transform);
 
         if (targetMap.MapId != userXform.MapID)
-        {
             return;
-        }
 
         var userPos = _transform.GetWorldPosition(userXform);
         var direction = targetMap.Position - userPos;
         var distance = Math.Min(component.Range, direction.Length);
 
         var damage = component.Damage * GetModifier(component, false);
-
-        // This should really be improved. GetEntitiesInArc uses pos instead of bounding boxes.
-        var entities = ArcRayCast(userPos, direction.ToWorldAngle(), component.Angle, distance, userXform.MapID, user);
+        var entities = ev.Entities;
 
         if (entities.Count == 0)
         {
@@ -546,6 +540,19 @@ public abstract class SharedMeleeWeaponSystem : EntitySystem
             return;
         }
 
+        // Validate client
+        for (var i = entities.Count - 1; i >= 0; i--)
+        {
+            if (ArcRaySuccessful(entities[i], userPos, direction.ToWorldAngle(), component.Angle, distance,
+                    userXform.MapID, user, session))
+            {
+                continue;
+            }
+
+            // Bad input
+            entities.RemoveAt(i);
+        }
+
         var targets = new List<EntityUid>();
         var damageQuery = GetEntityQuery<DamageableComponent>();
 
@@ -633,7 +640,7 @@ public abstract class SharedMeleeWeaponSystem : EntitySystem
         }
     }
 
-    private HashSet<EntityUid> ArcRayCast(Vector2 position, Angle angle, Angle arcWidth, float range, MapId mapId, EntityUid ignore)
+    protected HashSet<EntityUid> ArcRayCast(Vector2 position, Angle angle, Angle arcWidth, float range, MapId mapId, EntityUid ignore)
     {
         // TODO: This is pretty sucky.
         var widthRad = arcWidth;
@@ -659,6 +666,13 @@ public abstract class SharedMeleeWeaponSystem : EntitySystem
         return resSet;
     }
 
+    protected virtual bool ArcRaySuccessful(EntityUid targetUid, Vector2 position, Angle angle, Angle arcWidth, float range,
+        MapId mapId, EntityUid ignore, ICommonSession? session)
+    {
+        // Only matters for server.
+        return true;
+    }
+
     private void PlayHitSound(EntityUid target, EntityUid? user, string? type, SoundSpecifier? hitSoundOverride, SoundSpecifier? hitSound)
     {
         var playedSound = false;