Improves and cleans up TabletopSystem further. (#4633)

Content.Server/Tabletop/TabletopSystem.Map.cs

@@ -0,0 +1,102 @@
+using System;
+using Content.Shared.GameTicking;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Map;
+using Robust.Shared.Maths;
+
+namespace Content.Server.Tabletop
+{
+    public partial class TabletopSystem
+    {
+        /// <summary>
+        ///     Separation between tabletops in the tabletop map.
+        /// </summary>
+        private const int TabletopSeparation = 100;
+
+        /// <summary>
+        ///     Map where all tabletops reside.
+        /// </summary>
+        public MapId TabletopMap { get; private set; } = MapId.Nullspace;
+
+        /// <summary>
+        ///     The number of tabletops created in the map.
+        ///     Used for calculating the position of the next one.
+        /// </summary>
+        private int _tabletops = 0;
+
+        /// <summary>
+        ///     Despite the name, this method is only used to subscribe to events.
+        /// </summary>
+        private void InitializeMap()
+        {
+            SubscribeLocalEvent<RoundRestartCleanupEvent>(OnRoundRestart);
+        }
+
+        /// <summary>
+        ///     Gets the next available position for a tabletop, and increments the tabletop count.
+        /// </summary>
+        /// <returns></returns>
+        private Vector2 GetNextTabletopPosition()
+        {
+            return UlamSpiral(_tabletops++) * TabletopSeparation;
+        }
+
+        /// <summary>
+        ///     Ensures that the tabletop map exists. Creates it if it doesn't.
+        /// </summary>
+        private void EnsureTabletopMap()
+        {
+            if (TabletopMap != MapId.Nullspace && _mapManager.MapExists(TabletopMap))
+                return;
+
+            TabletopMap = _mapManager.CreateMap();
+            _tabletops = 0;
+
+            var mapComp = ComponentManager.GetComponent<IMapComponent>(_mapManager.GetMapEntityId(TabletopMap));
+
+            // Lighting is always disabled in tabletop world.
+            mapComp.LightingEnabled = false;
+            mapComp.Dirty();
+        }
+
+        /// <summary>
+        ///     Algorithm for mapping scalars to 2D positions in the same pattern as an Ulam Spiral.
+        /// </summary>
+        /// <param name="n">Scalar to map to a 2D position.</param>
+        /// <returns>The mapped 2D position for the scalar.</returns>
+        private Vector2i UlamSpiral(int n)
+        {
+            var k = (int)MathF.Ceiling(MathF.Sqrt(n) - 1) / 2;
+            var t = 2 * k + 1;
+            var m = (int)MathF.Pow(t, 2);
+            t--;
+
+            if (n >= m - t)
+                return new Vector2i(k - (m - n), -k);
+
+            m -= t;
+
+            if (n >= m - t)
+                return new Vector2i(-k, -k + (m - n));
+
+            m -= t;
+
+            if (n >= m - t)
+                return new Vector2i(-k + (m - n), k);
+
+            return new Vector2i(k, k - (m - n - t));
+        }
+
+        private void OnRoundRestart(RoundRestartCleanupEvent _)
+        {
+            if (TabletopMap == MapId.Nullspace || !_mapManager.MapExists(TabletopMap))
+                return;
+
+            // This will usually *not* be the case, but better make sure.
+            _mapManager.DeleteMap(TabletopMap);
+
+            // Reset tabletop count.
+            _tabletops = 0;
+        }
+    }
+}