$subd
The QC command $subd
is used to mark a model to be tessellated in run-time. This can be used to make models appear smoother than they actually are.
It also is needed to make $displacementmap work.

mat_tessellationlevel <1-16>
, with higher values rendering more polygons.

$subd
only works with quads and n-gons with more than 3 edges. This effectively makes the SMD format unusable, meaning you have to use the DMX format, as SMD only supports triangles. The SMD format can still be used for animations, though.Syntax
$subd
Note that $subd must be placed before your model line.
Example
$modelname "example/subdivision.mdl" $cdmaterials "example/subdivision" $subd $body test "subdivison.dmx" $sequence idle "subdivision_idle.smd"