The Wall Worm VMF Exporter handles the export of brush geometry (also known as world geometry) differently than the Convexity VMF Exporter. Convexity assumes that all objects in the scene are part of the world brush export; for the Wall Worm VMF Exporter, that is not true. For the most part, you have to tell Wall Worm what objects are part of the World Brush Geometry.

To tell Wall Worm that a piece of geometry should be part of the brush export, select the objects and click the Add button in Anvil under Brush Geometry in the Export Tags area.

Also, all geometry in layers called "Convexity Walls" and "Convexity Floors" are assumed to be convex geometry that will export as brush geometry.

• When you tag an object as a brush, Anvil will do a check to see if the object is Convex using PhysX/MassFX. That check is only available if using a version of Max that has MassFX or if you have installed the nVidia PhysX Plugin for 3ds Max.
• The convexity check of brush goemetry is not foolproof and sometimes reports false positives. When you add objects that are suspicious of not being Convex, you'll get a prompt to check the MAXScript listener (F11) to see a list of potentially invalid brush geometry.
• Even convex shapes can be invalid if they contain coplanar faces. An example of this is the Pyramid primitive (the bottom has four coplanar faces) or a Box primitive with multiple height/width/length segments (where each side had multiple polygons on the side). For things like Box, simply make sure that all height, width and length segments are set to 1. For things like the pyramid, you'll have to either manually edit the bottom to have one polygon, turn it into a model (with WWMT) or create a custom pyramid primitve.