Initial commit: OpenRA game engine

Fork from OpenRA/OpenRA with one-click launch script (start-ra.cmd)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

OpenRA.Mods.Common/Traits/World/CliffBackImpassabilityLayer.cs

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+#region Copyright & License Information
+/*
+ * Copyright (c) The OpenRA Developers and Contributors
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System.Linq;
+using OpenRA.Graphics;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.Common.Traits
+{
+	[Desc("Sets a custom terrain type for cells that are obscured by back-facing cliffs.",
+		"This trait replicates the default CliffBackImpassability=2 behaviour from the TS/RA2 rules.ini.")]
+	[TraitLocation(SystemActors.World | SystemActors.EditorWorld)]
+	sealed class CliffBackImpassabilityLayerInfo : TraitInfo
+	{
+		public readonly string TerrainType = "Impassable";
+
+		public override object Create(ActorInitializer init) { return new CliffBackImpassabilityLayer(this); }
+	}
+
+	sealed class CliffBackImpassabilityLayer : IWorldLoaded
+	{
+		readonly CliffBackImpassabilityLayerInfo info;
+
+		public CliffBackImpassabilityLayer(CliffBackImpassabilityLayerInfo info)
+		{
+			this.info = info;
+		}
+
+		public void WorldLoaded(World w, WorldRenderer wr)
+		{
+			var tileType = w.Map.Rules.TerrainInfo.GetTerrainIndex(info.TerrainType);
+
+			// Units are allowed behind cliffs *only* if they are part of a tunnel portal
+			var tunnelPortals = w.WorldActor.Info.TraitInfos<TerrainTunnelInfo>()
+				.SelectMany(mti => mti.PortalCells())
+				.ToHashSet();
+
+			foreach (var uv in w.Map.AllCells.MapCoords)
+			{
+				if (tunnelPortals.Contains(uv.ToCPos(w.Map)))
+					continue;
+
+				// All the map cells that visually overlap the current cell
+				var testCells = w.Map.ProjectedCellsCovering(uv)
+					.SelectMany(w.Map.Unproject);
+				if (testCells.Any(x => x.V >= uv.V + 4))
+					w.Map.CustomTerrain[uv] = tileType;
+			}
+		}
+	}
+}