$texture2 lumstart

$texture2_lumstart & $texture2_lumend allows you to adjust the luminance range used to modulate the blending in Lightmapped_4WayBlend materials.

The luminance of the texture is calculated using dot(texture.rgb, float3(0.2125, 0.7154, 0.0721)) in the shader.

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