well… the 3d space could be easy to get if you uv unwrap the cube or any shape as a volume. basicly copy the position into 2 uvs to sample. unfortunately lightmass seems to only uses a single texcoord pair for the opacity sampling, so… the z-axis (in this case) is lost. bummer. or some mods required.
the raymarch is a different beast anyway, tho. a direction is required. and i have no idea if lightmass would evaluate the “shadow march” loop.
