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A sample scene with two rooms.
The default visleaf structure for the above scene. Note how leaf 2 cannot see leaf 3.
Not to be confused with VisGroup.

Each visleaf (sometimes referred to simply as a leaf) is a hollow volume in a map which defines a 'cluster' of visible surfaces. Every visible surface of a map is part of one visleaf or another. Visleafs are used primarily by the Rendering Engine to determine (before rendering each frame) which areas of the map might need to be rendered on screen. When any part of a visleaf is potentially visible from any part of the current visleaf, the entire contents of that visleaf are considered for rendering.

Visleafs are generated automatically from the BSP tree by the VVIS compile tool. Each (internal) surface of a visleaf is either a World brush surface or a Portal to an adjacent visleaf.


There are three ways to inspect visleaves:

  • From the Orange Box version of Hammer, the leaves of the current map can be viewed directly in the 3D view through the menu option Map > Load Portal File. This displays leaf edges that touch other edges as thick blue lines.
  • From the desktop, the glview tool application (located in the common\[game]\bin folder) can be used.
Tip.png Tip: For even more clarity use auto visgroups to remove objects from your map that don't block visibility – i.e. everything but "World Geometry".
Note.png Note: Do not confuse visleaves with the squares outlining worldbrush geography seen if you use mat_wireframe 3.

See also