A light map is an additional texture layer that's used for displaying pre-rendered shadows. Objects
without light maps (anything besides BSP geometry) use their vertices for determining lighting; with a
light map, additional points (by default, one for every 16 world units) are used.
This lab demonstrates the effects of changing the light map scale on faces in a WTStudio level; setting
the light map scale to 0.5 uses lighting points spaced 8 world units apart, and setting it to 0.1
uses points spaced 1.6 world units apart. Try setting the light map scale to different values, and note how
the shadows become crisper as the light map scale decreases.
Points to Remember
Decreasing the light map scale increases the shadow resolution on the surfaces of your level, but
it also increases the amount of resources your level will require.
If you want crisp shadows for one specific area, you can set the light map scale for each face of
your BSP geometry; you don't need to decrease the light map scale for your level as a whole, or even
for a whole brush.
Only static (non-dynamic) lights will produce shadows.
BSP geometry will only cast shadows within its model group (All brushes that are not part of a model group
are treated as being in the same group). So, a brush that's part of a model group will not cast a shadow on
a brush that's not part of a model group (or in a different model group), and vice versa.
If needed, you can set a different scale for the U and V (texture "X" and "Y") coordinates for the light
maps in your world; this will result in oblong (rectangular) pixelation of your light maps. This has limited
application, but it may be handy in some situations.
When included in the downloaded file, lightmaps can be quite large, especially if a fine light map scale is
used. If you want to optimize the download time for your level, you can set the light maps to be generated
on the client, rather than included in the downloaded file. You can set this in the properties tab for
the Model node in the Lists tab. This will require more processor effort to load the level on the
client machine, but will substantially reduce the download time.
Note that transparency does not affect
shadow depth; the sphere on the left casts the same shadow as it would if it were opaque.
Invisible brushes will also cast shadows, unless they are part of a Model object.