$texture1 lumstart

$texture1_lumstart, $texture1_lumend, $texture2_lumstart, $texture2_lumend, $texture3_lumstart, $texture3_lumend, $texture4_lumstart, and $texture4_lumend allow you to adjust the luminance range used to modulate the blending in Lightmapped_4WayBlend materials.

A smoothstep operation is performed on the luminance of the texture, like so: smoothstep(lumstart, lumend, luminanceof(texture)).