Fix decal draw-order (#22953)

* Fix decal draw-order

Using the new overlayspace ensures they don't draw above grids above them.

* a

Content.Client/Decals/Overlays/DecalOverlay.cs

@@ -2,18 +2,17 @@ using Content.Shared.Decals;
 using Robust.Client.GameObjects;
 using Robust.Client.Graphics;
 using Robust.Shared.Enums;
+using Robust.Shared.Map;
 using Robust.Shared.Prototypes;
 
 namespace Content.Client.Decals.Overlays
 {
-    public sealed class DecalOverlay : Overlay
+    public sealed class DecalOverlay : GridOverlay
     {
         private readonly SpriteSystem _sprites;
         private readonly IEntityManager _entManager;
         private readonly IPrototypeManager _prototypeManager;
 
-        public override OverlaySpace Space => OverlaySpace.WorldSpaceBelowEntities;
-
         private readonly Dictionary<string, (Texture Texture, bool SnapCardinals)> _cachedTextures = new(64);
 
         public DecalOverlay(
@@ -28,22 +27,29 @@ namespace Content.Client.Decals.Overlays
 
         protected override void Draw(in OverlayDrawArgs args)
         {
+            if (args.MapId == MapId.Nullspace)
+                return;
+
+            var grid = Grid;
+
+            if (!_entManager.TryGetComponent(grid, out DecalGridComponent? decalGrid) ||
+                !_entManager.TryGetComponent(grid, out TransformComponent? xform))
+            {
+                return;
+            }
+
+            if (xform.MapID != args.MapId)
+                return;
+
             // Shouldn't need to clear cached textures unless the prototypes get reloaded.
             var handle = args.WorldHandle;
             var xformSystem = _entManager.System<TransformSystem>();
             var eyeAngle = args.Viewport.Eye?.Rotation ?? Angle.Zero;
 
-            var gridQuery = _entManager.AllEntityQueryEnumerator<DecalGridComponent, TransformComponent>();
-
-            while (gridQuery.MoveNext(out var decalGrid, out var xform))
-            {
-                if (xform.MapID != args.MapId)
-                    continue;
-
             var zIndexDictionary = decalGrid.DecalRenderIndex;
 
             if (zIndexDictionary.Count == 0)
-                    continue;
+                return;
 
             var (_, worldRot, worldMatrix) = xformSystem.GetWorldPositionRotationMatrix(xform);
 
@@ -75,7 +81,6 @@ namespace Content.Client.Decals.Overlays
                         handle.DrawTexture(cache.Texture, decal.Coordinates, angle, decal.Color);
                 }
             }
-            }
 
             handle.SetTransform(Matrix3.Identity);
         }