Fix & speed up explosion lookup (#9526)

* Speed up explosion lookup

* Ah. Fuck.

Content.Server/Explosion/EntitySystems/ExplosionSystem.Processing.cs

@@ -202,30 +202,16 @@ public sealed partial class ExplosionSystem : EntitySystem
 
         // get the entities on a tile. Note that we cannot process them directly, or we get
         // enumerator-changed-while-enumerating errors.
-        List<(EntityUid, TransformComponent?) > list = new();
+        List<TransformComponent> list = new();
+        var state = (list, processed, xformQuery);
 
-        void AddIntersecting(List<(EntityUid, TransformComponent?)> listy)
+        // get entities:
-        {
+        lookup.Tree.QueryAabb(ref state, GridQueryCallback, gridBox, true);
-            // TODO directly query lookup.Tree
-            foreach (var uid in _entityLookup.GetLocalEntitiesIntersecting(lookup, ref gridBox, flags))
-            {
-                if (processed.Contains(uid))
-                    continue;
-
-                if (!xformQuery.TryGetComponent(uid, out var xform))
-                    continue;
-
-                listy.Add((uid, xform));
-            }
-        }
-
-        AddIntersecting(list);
 
         // process those entities
-        foreach (var (entity, xform) in list)
+        foreach (var xform in list)
         {
-            processed.Add(entity);
+            ProcessEntity(xform.Owner, epicenter, damage, throwForce, id, damageQuery, physicsQuery, xform);
-            ProcessEntity(entity, epicenter, damage, throwForce, id, damageQuery, physicsQuery, xform);
         }
 
         // process anchored entities
@@ -261,18 +247,28 @@ public sealed partial class ExplosionSystem : EntitySystem
             return !tileBlocked;
 
         list.Clear();
-        AddIntersecting(list);
+        lookup.Tree.QueryAabb(ref state, GridQueryCallback, gridBox, true);
 
-        foreach (var (entity, xform) in list)
+        foreach (var xform in list)
         {
             // Here we only throw, no dealing damage. Containers n such might drop their entities after being destroyed, but
             // they should handle their own damage pass-through, with their own damage reduction calculation.
-            ProcessEntity(entity, epicenter, null, throwForce, id, damageQuery, physicsQuery, xform);
+            ProcessEntity(xform.Owner, epicenter, null, throwForce, id, damageQuery, physicsQuery, xform);
         }
 
         return !tileBlocked;
     }
 
+    private bool GridQueryCallback(
+        ref (List<TransformComponent> List, HashSet<EntityUid> Processed, EntityQuery<TransformComponent> XformQuery) state,
+        in EntityUid uid)
+    {
+        if (state.Processed.Add(uid) && state.XformQuery.TryGetComponent(uid, out var xform))
+            state.List.Add(xform);
+
+        return true;
+    }
+
     /// <summary>
     ///     Same as <see cref="ExplodeTile"/>, but for SPAAAAAAACE.
     /// </summary>
@@ -290,44 +286,18 @@ public sealed partial class ExplosionSystem : EntitySystem
         EntityQuery<PhysicsComponent> physicsQuery,
         LookupFlags flags)
     {
-        var gridBox = new Box2(tile * DefaultTileSize, (DefaultTileSize, DefaultTileSize));
+        var gridBox = Box2.FromDimensions(tile * DefaultTileSize, (DefaultTileSize, DefaultTileSize));
         var worldBox = spaceMatrix.TransformBox(gridBox);
-        List<(EntityUid, TransformComponent)> list = new();
+        var list = new List<TransformComponent>();
+        var state = (list, processed, invSpaceMatrix, lookup.Owner, xformQuery, gridBox);
 
-        void AddIntersecting(List<(EntityUid, TransformComponent)> listy)
+        // get entities:
+        lookup.Tree.QueryAabb(ref state, SpaceQueryCallback, worldBox, true);
+
+        foreach (var xform in state.Item1)
         {
-            // TODO directly query lookup.Tree
+            processed.Add(xform.Owner);
-            foreach (var uid in _entityLookup.GetEntitiesIntersecting(lookup, ref worldBox, flags))
+            ProcessEntity(xform.Owner, epicenter, damage, throwForce, id, damageQuery, physicsQuery, xform);
-            {
-                if (processed.Contains(uid))
-                    return;
-
-                var xform = xformQuery.GetComponent(uid);
-
-                if (xform.ParentUid == lookup.Owner)
-                {
-                    // parented directly to the map, use local position
-                    if (gridBox.Contains(invSpaceMatrix.Transform(xform.LocalPosition)))
-                        listy.Add((uid, xform));
-
-                    return;
-                }
-
-                // "worldPos" should be the space/map local position.
-                var worldPos = _transformSystem.GetWorldPosition(xform, xformQuery);
-
-                // finally check if it intersects our tile
-                if (gridBox.Contains(invSpaceMatrix.Transform(worldPos)))
-                    listy.Add((uid, xform));
-            }
-        }
-
-        AddIntersecting(list);
-
-        foreach (var (entity, xform) in list)
-        {
-            processed.Add(entity);
-            ProcessEntity(entity, epicenter, damage, throwForce, id, damageQuery, physicsQuery, xform);
         }
 
         if (throwForce <= 0)
@@ -336,13 +306,39 @@ public sealed partial class ExplosionSystem : EntitySystem
         // Also, throw any entities that were spawned as shrapnel. Compared to entity spawning & destruction, this extra
         // lookup is relatively minor computational cost, and throwing is disabled for nukes anyways.
         list.Clear();
-        AddIntersecting(list);
+        lookup.Tree.QueryAabb(ref state, SpaceQueryCallback, worldBox, true);
-        foreach (var (entity, xform) in list)
+
+        foreach (var xform in list)
         {
-            ProcessEntity(entity, epicenter, null, throwForce, id, damageQuery, physicsQuery, xform);
+            ProcessEntity(xform.Owner, epicenter, null, throwForce, id, damageQuery, physicsQuery, xform);
         }
     }
 
+    private bool SpaceQueryCallback(
+        ref (List<TransformComponent> List, HashSet<EntityUid> Processed, Matrix3 InvSpaceMatrix, EntityUid LookupOwner, EntityQuery<TransformComponent> XformQuery, Box2 GridBox) state,
+        in EntityUid uid)
+    {
+        if (state.Processed.Contains(uid))
+            return true;
+
+        var xform = state.XformQuery.GetComponent(uid);
+
+        if (xform.ParentUid == state.LookupOwner)
+        {
+            // parented directly to the map, use local position
+            if (state.GridBox.Contains(state.InvSpaceMatrix.Transform(xform.LocalPosition)))
+                state.List.Add(xform);
+
+            return true;
+        }
+
+        // finally check if it intersects our tile
+        if (state.GridBox.Contains(state.InvSpaceMatrix.Transform(_transformSystem.GetWorldPosition(xform, state.XformQuery))))
+            state.List.Add(xform);
+
+        return true;
+    }
+
     /// <summary>
     ///     This function actually applies the explosion affects to an entity.
     /// </summary>
@@ -497,7 +493,7 @@ sealed class Explosion
     public readonly MapCoordinates Epicenter;
 
     /// <summary>
-    ///     The matrix that defines the referance frame for the explosion in space.
+    ///     The matrix that defines the reference frame for the explosion in space.
     /// </summary>
     private readonly Matrix3 _spaceMatrix;