[server] Implement Rectangle.Overlap()

Nibriboard/Client/NibriClient.cs

@@ -237,9 +237,12 @@ namespace Nibriboard.Client
 		/// <returns>Whether this client can see the chunk located at the specified chunk reference</returns>
 		public bool CanSee(ChunkReference chunkRef)
 		{
-			LocationReference chunkLocation = chunkRef.InPlanespace();
+			if(chunkRef.Plane != CurrentPlane)
+				return false;
+			
 			Rectangle chunkArea = chunkRef.InPlanespaceRectangle();
 
+			return chunkArea.Overlap(CurrentViewPort);
 		}
 
 		#region Message Handlers

Nibriboard/Utilities/Rectangle.cs

@@ -119,6 +119,22 @@ namespace SBRL.Utilities
 			Width = width;
 			Height = height;
 		}
+
+		/// <summary>
+		/// Figures out whether this rectangle overlaps another rectangle.
+		/// </summary>
+		/// <param name="otherRectangle">The other rectangle to check the overlap of.</param>
+		/// <returns>Whether this rectangle overlaps another rectangle.</returns>
+		public bool Overlap(Rectangle otherRectangle)
+		{
+			if(Top > otherRectangle.Bottom &&
+			   Bottom < otherRectangle.Top &&
+			   Left > otherRectangle.Right &&
+			   Right < otherRectangle.Left)
+				return false;
+
+			return true;
+		}
 	}
 }