Could anybody point me to a good resource to understand the differences between these? When to assign and when to attach material and how this applies to Luxology as well. I would be very happy to know about these.
Thank you so much.
Sincerely,
Rabi
Yep, ditto what they said.
Assign is used for all your general materials that apply to all objects on the layer. So typically, different building materials will be on their own layer/colour, so you can easily apply a material to all of them with a single assignment.
Attach is for special cases where you maybe want one object of an particular material to be different, or even one face of one object.
A couple of warnings though. You cannot assign materials to a true colour, so if you want to use true colours as kind of placeholders so your objects look rightish before texturing, make sure you do it in an override, or you won't be able to assign a material to them.
Secondly, you cant attach a material to an object in a reference file (god knows why, surely it's possible to get store a path to an object in a reference file within the material table of another file), so if you think you're going to get around the above issue by attaching, it only works in the actual design file.
The two issues above make it a royal pain in the proverbial to put together final rendering files which reference in things like sketchup files (which inevitably contain true colours) or files with true colours. Sometimes sketchup files seem to bring in their own palette automatically, but sometimes not, it seems to depend on the file.