"The mesh material must be a ProjectedMaterial" - why all of them?

[molnarm]

Hi,

Thanks for the awesome library!

The only thing I don't understand is why do you validate that when a mesh has multiple materials, all of them must be ProjectedMaterial? From a quick glance at the source, it looks unnecessary to me.

I'd like to have images projected on a model with existing textures. I tried commenting out that check and it still works perfectly, so I'm wondering why does it matter what other materials are there?