An extension for srcds servers that draws invisible walls, ladders, buttons and other hidden map objects for players. The core is written in C++ and reads the map's BSP file directly, without third-party libraries, including decompressing LZMA-compressed lumps. The shape of each brush is reconstructed from the planes of its faces using the Sutherland-Hodgman algorithm, and degenerate and broken polygons are discarded. The extension decides which brushes to treat as invisible based on surface flags, materials and entity properties. The finished edges are passed to a SourcePawn plugin, which draws the nearest of them as beams. Each map can have its own settings in a separate config.