A few weeks ago I needed to have a dynamic way of selecting all the Face/Material IDs of an object and deleting everything else. My first thought was, well the Poly_Select modifier has a select by Face/Material ID. However that isn’t dynamic, if your underlying mesh changes, the Poly Select doesn’t update…. sigh.
I thought about a scripted approach with an Edit Poly modifier, but decided that was going to be too slow.
In the end I had a demo of Genome from Thinkbox (an awesome tool, if not a bit scary at first). And I made a cool little custom modifier that allowed me to select by Material ID, or select by not the Material ID.
This worked, but then the other day I realised I had over-engineered the solution. There’s a modifier which I use over and over again to make things procedural, and it’s one of 3ds Max’s most powerful tools. Volume Select allows you to keep things procedural, you can create volume shapes to recreate the manual process of going into a sub-selection and drawing out a marquee to select polygons, you can use Soft-Selection as well which is always nice. You can also select by a map material which is super useful, especially as it supports 3d maps. However the one feature I’d completely forgotten about is that it can also select by material ID! You can also Invert the selection in this modifier and thus use a DeleteMesh modifier (Again one that is under-used by most people because they don’t realise when you have a stack-selection it become very useful!)