Add tile overlay edge priority (#4341)

Robust.Client/Map/TileEdgeOverlay.cs

@@ -61,11 +61,16 @@ public sealed class TileEdgeOverlay : Overlay
 
                         var neighborIndices = new Vector2i(tileRef.GridIndices.X + x, tileRef.GridIndices.Y + y);
                         var neighborTile = grid.GetTileRef(neighborIndices);
+                        var neighborDef = _tileDefManager[neighborTile.Tile.TypeId];
 
                         // If it's the same tile then no edge to be drawn.
                         if (tileRef.Tile.TypeId == neighborTile.Tile.TypeId)
                             continue;
 
+                        // Don't draw if the the neighbor tile edges should draw over us (or if we have the same priority)
+                        if (neighborDef.EdgeSprites.Count != 0 && neighborDef.EdgeSpritePriority >= tileDef.EdgeSpritePriority)
+                            continue;
+
                         var direction = new Vector2i(x, y).AsDirection();
 
                         // No edge tile

Robust.Shared/Map/ITileDefinition.cs

@@ -30,10 +30,16 @@ namespace Robust.Shared.Map
         ResPath? Sprite { get; }
 
         /// <summary>
-        /// Possible sprites to use if we're neighboring another tile.
+        ///     Possible sprites to use if we're neighboring another tile.
         /// </summary>
         Dictionary<Direction, ResPath> EdgeSprites { get; }
 
+        /// <summary>
+        ///     When drawing adjacent tiles that both specify edge sprites, the one with the higher priority
+        ///     is always solely drawn.
+        /// </summary>
+        int EdgeSpritePriority { get; }
+
         /// <summary>
         ///     Physics objects that are interacting on this tile are slowed down by this float.
         /// </summary>