Only render shroud/ore that is in the current viewport

OpenRA.Game/Graphics/Viewport.cs

@@ -158,5 +158,14 @@ namespace OpenRA.Graphics
 			if (localPlayer.Shroud.Disabled) return null;
 			return localPlayer.Shroud.Bounds;
 		}
+		
+		public Rectangle ViewBounds()
+		{
+			int2 boundary = new int2(3,3); // Add a curtain of cells around the viewport to account for rounding errors
+			var origin = new int2((int)(scrollPosition.X/Game.CellSize), (int)(scrollPosition.Y/Game.CellSize));		
+			var tl = ViewToWorld(origin).ToInt2() - boundary;
+			var br = ViewToWorld(origin + new int2(Width, Height)).ToInt2() + boundary;
+			return Rectangle.FromLTRB(tl.X, tl.Y, br.X, br.Y);
+		}
 	}
 }

OpenRA.Game/ShroudRenderer.cs

@@ -145,7 +145,7 @@ namespace OpenRA
 			}
 
 			var clipRect = Bounds.HasValue ? Rectangle.Intersect(Bounds.Value, map.Bounds) : map.Bounds;
-
+			clipRect = Rectangle.Intersect(Game.viewport.ViewBounds(), clipRect);
 			var miny = clipRect.Top;
 			var maxy = clipRect.Bottom;
 			var minx = clipRect.Left;

OpenRA.Game/Traits/World/ResourceLayer.cs

@@ -29,6 +29,8 @@ namespace OpenRA.Traits
 			var cliprect = Game.viewport.ShroudBounds().HasValue
 				? Rectangle.Intersect(Game.viewport.ShroudBounds().Value, world.Map.Bounds) : world.Map.Bounds;
 
+			cliprect = Rectangle.Intersect(Game.viewport.ViewBounds(), cliprect);
+			
 			var minx = cliprect.Left;
 			var maxx = cliprect.Right;