Run grid traversal on entity spawn (#4796)

* Run grid traversal on entity spawn

* Add test

* Fix tests

Robust.Shared/GameObjects/Systems/SharedGridTraversalSystem.cs

@@ -25,9 +25,15 @@ internal sealed class SharedGridTraversalSystem : EntitySystem
     public override void Initialize()
     {
         base.Initialize();
+        SubscribeLocalEvent<TransformStartupEvent>(OnStartup);
         _transform.OnGlobalMoveEvent += OnMove;
     }
 
+    private void OnStartup(ref TransformStartupEvent ev)
+    {
+        CheckTraverse(ev.Entity.Owner, ev.Entity.Comp);
+    }
+
     public override void Shutdown()
     {
         _transform.OnGlobalMoveEvent -= OnMove;
@@ -92,7 +98,7 @@ internal sealed class SharedGridTraversalSystem : EntitySystem
             : Transform(xform.ParentUid).LocalMatrix.Transform(xform.LocalPosition);
 
         // Change parent if necessary
-        if (_mapManager.TryFindGridAt(xform.MapID, mapPos, out var gridUid, out _))
+        if (_mapManager.TryFindGridAt(map, mapPos, out var gridUid, out _))
         {
             // Some minor duplication here with AttachParent but only happens when going on/off grid so not a big deal ATM.
             if (gridUid != xform.GridUid)

Robust.Shared/GameObjects/Systems/SharedTransformSystem.Component.cs

@@ -332,7 +332,7 @@ public abstract partial class SharedTransformSystem
         var parentEv = new EntParentChangedMessage(uid, null, MapId.Nullspace, xform);
         RaiseLocalEvent(uid, ref parentEv, true);
 
-        var ev = new TransformStartupEvent(xform);
+        var ev = new TransformStartupEvent((uid, xform));
         RaiseLocalEvent(uid, ref ev, true);
 
         DebugTools.Assert(!xform.NoLocalRotation || xform.LocalRotation == 0, $"NoRot entity has a non-zero local rotation. entity: {ToPrettyString(uid)}");
@@ -1334,22 +1334,15 @@ public abstract partial class SharedTransformSystem
         if (!xform.ParentUid.IsValid())
             return false;
 
-        EntityUid newParent;
-        var oldPos = GetWorldPosition(xform, XformQuery);
-        if (_mapManager.TryFindGridAt(xform.MapID, oldPos, XformQuery, out var gridUid, out _))
-        {
-            newParent = gridUid;
-        }
-        else if (_mapManager.GetMapEntityId(xform.MapID) is { Valid: true } mapEnt)
-        {
-            newParent = mapEnt;
-        }
-        else
-        {
+        if (xform.MapUid is not { } map)
             return false;
-        }
 
-        coordinates = new(newParent, GetInvWorldMatrix(newParent, XformQuery).Transform(oldPos));
+        var newParent = map;
+        var oldPos = GetWorldPosition(xform);
+        if (_mapManager.TryFindGridAt(map, oldPos, out var gridUid, out _))
+            newParent = gridUid;
+
+        coordinates = new(newParent, GetInvWorldMatrix(newParent).Transform(oldPos));
         return true;
     }
     #endregion

Robust.Shared/GameObjects/Systems/SharedTransformSystem.cs

@@ -256,14 +256,10 @@ namespace Robust.Shared.GameObjects
     }
 
     [ByRefEvent]
-    public readonly struct TransformStartupEvent
+    public readonly struct TransformStartupEvent(Entity<TransformComponent> entity)
     {
-        public readonly TransformComponent Component;
-
-        public TransformStartupEvent(TransformComponent component)
-        {
-            Component = component;
-        }
+        public readonly Entity<TransformComponent> Entity = entity;
+        public TransformComponent Component => Entity.Comp;
     }
 
     /// <summary>

Robust.Shared/Map/IMapManager.cs

@@ -114,6 +114,18 @@ namespace Robust.Shared.Map
         /// <returns>Returns true when a grid was found under the location.</returns>
         bool TryFindGridAt(MapId mapId, Vector2 worldPos, out EntityUid uid, [NotNullWhen(true)] out MapGridComponent? grid);
 
+        /// <summary>
+        /// Attempts to find the map grid under the map location.
+        /// </summary>
+        /// <remarks>
+        /// This method will never return the map's default grid.
+        /// </remarks>
+        /// <param name="mapId">Map to search.</param>
+        /// <param name="worldPos">Location on the map to check for a grid.</param>
+        /// <param name="grid">Grid that was found, if any.</param>
+        /// <returns>Returns true when a grid was found under the location.</returns>
+        bool TryFindGridAt(EntityUid mapId, Vector2 worldPos, out EntityUid uid, [NotNullWhen(true)] out MapGridComponent? grid);
+
         /// <summary>
         /// Attempts to find the map grid under the map location.
         /// </summary>

Robust.UnitTesting/Server/Maps/MapLoaderTest.cs

@@ -97,6 +97,8 @@ entities:
             entMan.EnsureComponent<PhysicsMapComponent>(mapUid);
             entMan.EnsureComponent<BroadphaseComponent>(mapUid);
 
+            var traversal = entMan.System<SharedGridTraversalSystem>();
+            traversal.Enabled = false;
             var mapLoad = IoCManager.Resolve<IEntitySystemManager>().GetEntitySystem<MapLoaderSystem>();
             if (!mapLoad.TryLoad(mapId, "/TestMap.yml", out var root)
                 || root.FirstOrDefault() is not { Valid:true } geid)
@@ -107,6 +109,7 @@ entities:
 
             var entity = entMan.GetComponent<TransformComponent>(geid)._children.Single();
             var c = entMan.GetComponent<MapDeserializeTestComponent>(entity);
+            traversal.Enabled = true;
 
             Assert.That(c.Bar, Is.EqualTo(2));
             Assert.That(c.Foo, Is.EqualTo(3));

Robust.UnitTesting/Shared/GameObjects/Systems/AnchoredSystemTests.cs

@@ -157,6 +157,9 @@ namespace Robust.UnitTesting.Shared.GameObjects.Systems
             var grid = mapMan.GetGrid(gridId);
             grid.SetTile(grid.TileIndicesFor(coordinates), new Tile(1));
 
+            var traversal = entMan.System<SharedGridTraversalSystem>();
+            traversal.Enabled = false;
+
             var subscriber = new Subscriber();
             int calledCount = 0;
             var ent1 = entMan.SpawnEntity(null, coordinates); // this raises MoveEvent, subscribe after
@@ -171,7 +174,9 @@ namespace Robust.UnitTesting.Shared.GameObjects.Systems
             {
                 Assert.That(ev.Entity, Is.EqualTo(ent1));
                 calledCount++;
+
             }
+            traversal.Enabled = true;
         }
 
         /// <summary>
@@ -510,6 +515,9 @@ namespace Robust.UnitTesting.Shared.GameObjects.Systems
             var grid = mapMan.GetGrid(gridId);
             grid.SetTile(grid.TileIndicesFor(coordinates), new Tile(1));
 
+            var traversal = entMan.System<SharedGridTraversalSystem>();
+            traversal.Enabled = false;
+
             var subscriber = new Subscriber();
             int calledCount = 0;
             var ent1 = entMan.SpawnEntity(null, coordinates); // this raises MoveEvent, subscribe after
@@ -525,6 +533,7 @@ namespace Robust.UnitTesting.Shared.GameObjects.Systems
                 Assert.That(ev.Entity, Is.EqualTo(ent1));
                 calledCount++;
             }
+            traversal.Enabled = true;
         }
 
         /// <summary>

Robust.UnitTesting/Shared/Physics/MapVelocity_Test.cs

@@ -38,6 +38,8 @@ namespace Robust.UnitTesting.Shared.Physics
             var system = entityManager.EntitySysManager;
             var physicsSys = system.GetEntitySystem<SharedPhysicsSystem>();
             var xformSystem = system.GetEntitySystem<SharedTransformSystem>();
+            var traversal = entityManager.System<SharedGridTraversalSystem>();
+            traversal.Enabled = false;
 
             await server.WaitAssertion(() =>
             {
@@ -93,6 +95,7 @@ namespace Robust.UnitTesting.Shared.Physics
                 Assert.That(velocities.Item1, Is.Approximately(linearVelocity, 1e-6));
                 Assert.That(velocities.Item2, Is.Approximately(angularVelocity, 1e-6));
             });
+            traversal.Enabled = true;
         }
 
         // Check that if something has more than one parent, the velocities are properly added
@@ -107,6 +110,8 @@ namespace Robust.UnitTesting.Shared.Physics
             var system = entityManager.EntitySysManager;
             var physicsSys = system.GetEntitySystem<SharedPhysicsSystem>();
             var xformSystem = system.GetEntitySystem<SharedTransformSystem>();
+            var traversal = entityManager.System<SharedGridTraversalSystem>();
+            traversal.Enabled = false;
 
             await server.WaitAssertion(() =>
             {
@@ -166,6 +171,7 @@ namespace Robust.UnitTesting.Shared.Physics
                 Assert.That(velocities.Item1, Is.Approximately(linearVelocity, 1e-6));
                 Assert.That(velocities.Item2, Is.Approximately(angularVelocity, 1e-6));
             });
+        traversal.Enabled = true;
         }
     }
 }

Robust.UnitTesting/Shared/TransformTests/GridTraversalTest.cs

@@ -0,0 +1,90 @@
+using System.Numerics;
+using System.Threading.Tasks;
+using NUnit.Framework;
+using Robust.Server.GameObjects;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Map;
+using Robust.Shared.Maths;
+
+namespace Robust.UnitTesting.Shared.TransformTests;
+
+public sealed class GridTraversalTest : RobustIntegrationTest
+{
+    [Test]
+    public async Task TestSpawnTraversal()
+    {
+        var server = StartServer();
+        await server.WaitIdleAsync();
+
+        var mapMan = server.ResolveDependency<IMapManager>();
+        var sEntMan = server.ResolveDependency<IEntityManager>();
+        var xforms = sEntMan.System<SharedTransformSystem>();
+        var mapSys = sEntMan.System<MapSystem>();
+
+        // Set up entities
+        MapId mapId = default!;
+        EntityUid map = default;
+        EntityUid grid = default;
+        Vector2 gridMapPos = default;
+        await server.WaitPost(() =>
+        {
+            mapId = mapMan.CreateMap();
+            map = mapMan.GetMapEntityId(mapId);
+
+            var gridComp = mapMan.CreateGridEntity(mapId);
+            grid = gridComp.Owner;
+            mapSys.SetTile(grid, gridComp, Vector2i.Zero, new Tile(1));
+            var gridCentre = new EntityCoordinates(grid, .5f, .5f);
+            gridMapPos = gridCentre.ToMap(sEntMan, xforms).Position;
+        });
+
+        for (int i = 0; i < 10; i++)
+        {
+            await server.WaitRunTicks(1);
+        }
+
+        await server.WaitPost(() =>
+        {
+            // Spawn an entity using map coordinates will get parented to the grid when spawning on the grid.
+            var entity = sEntMan.SpawnEntity(null, new MapCoordinates(gridMapPos, mapId));
+            Assert.That(sEntMan.GetComponent<TransformComponent>(entity).MapUid, Is.EqualTo(map));
+            Assert.That(sEntMan.GetComponent<TransformComponent>(entity).GridUid, Is.EqualTo(grid));
+            Assert.That(sEntMan.GetComponent<TransformComponent>(entity).ParentUid, Is.EqualTo(grid));
+            sEntMan.Deleted(entity);
+
+            // Spawning using map entity coords will still parent to the grid when spawning on the grid.
+            entity = sEntMan.SpawnEntity(null, new EntityCoordinates(map, gridMapPos));
+            Assert.That(sEntMan.GetComponent<TransformComponent>(entity).MapUid, Is.EqualTo(map));
+            Assert.That(sEntMan.GetComponent<TransformComponent>(entity).GridUid, Is.EqualTo(grid));
+            Assert.That(sEntMan.GetComponent<TransformComponent>(entity).ParentUid, Is.EqualTo(grid));
+            sEntMan.Deleted(entity);
+
+            // and using local grid coords also works.
+            entity = sEntMan.SpawnEntity(null, new EntityCoordinates(grid, 0.5f, 0.5f));
+            Assert.That(sEntMan.GetComponent<TransformComponent>(entity).MapUid, Is.EqualTo(map));
+            Assert.That(sEntMan.GetComponent<TransformComponent>(entity).GridUid, Is.EqualTo(grid));
+            Assert.That(sEntMan.GetComponent<TransformComponent>(entity).ParentUid, Is.EqualTo(grid));
+            sEntMan.Deleted(entity);
+
+            // Spawning an entity far away from the grid will leave it parented to the map.
+            entity = sEntMan.SpawnEntity(null, new MapCoordinates(new Vector2(100f, 100f), mapId));
+            Assert.That(sEntMan.GetComponent<TransformComponent>(entity).MapUid, Is.EqualTo(map));
+            Assert.Null(sEntMan.GetComponent<TransformComponent>(entity).GridUid);
+            Assert.That(sEntMan.GetComponent<TransformComponent>(entity).ParentUid, Is.EqualTo(map));
+            sEntMan.Deleted(entity);
+
+            entity = sEntMan.SpawnEntity(null, new EntityCoordinates(map, new Vector2(100f, 100f)));
+            Assert.That(sEntMan.GetComponent<TransformComponent>(entity).MapUid, Is.EqualTo(map));
+            Assert.Null(sEntMan.GetComponent<TransformComponent>(entity).GridUid);
+            Assert.That(sEntMan.GetComponent<TransformComponent>(entity).ParentUid, Is.EqualTo(map));
+            sEntMan.Deleted(entity);
+
+            entity = sEntMan.SpawnEntity(null, new EntityCoordinates(grid, 100f, 100f));
+            Assert.That(sEntMan.GetComponent<TransformComponent>(entity).MapUid, Is.EqualTo(map));
+            Assert.Null(sEntMan.GetComponent<TransformComponent>(entity).GridUid);
+            Assert.That(sEntMan.GetComponent<TransformComponent>(entity).ParentUid, Is.EqualTo(map));
+            sEntMan.Deleted(entity);
+        });
+    }
+}
+