HL2 Displacement Mapping

[Mr. Happy]

Smoothing groups are a bit finicky.

A luxel is a pixel of light. You can think of a lightmap as really low resolution texture. A lightmap scale of 1 means that there is one luxel for every one pixel, a lightmap scale of 4 means that there is one luxel for every 4 pixels.

So, if you have a 2x2 face with a lightmap scale of 16 it can't fit an entire luxel (it'll still bit lit though, of course).

You can view the lightmap by clicking "camera" in your 3D view and selecting "Lightmap grid"

One quirk of smoothing groups is that there is a angular threshold, which you can change with the -smooth # compile switch on vrad. If the faces are at an angle to each other greater than this they won't be smoothed. Default is 45 degrees.