Depending on what you want, there are several possibilities.
- combine the polygon selections that share the same material into a single selection.
- bake your materials into a color ID map and use it e.g. in Substance Painter or Quexie to generate your PBR material values.
for 1:
you should combine seperate objects into a single mesh with polygon selections (select them, right click, combine objects)
If you combine objects that have a different material assigned, it will auto-create polygon selections and assign the materials to them.
If you allready have polygon selections assigned to parts of your meshes that are going to be combinewd, it’ll keep them.
Depending on your naming conventions of those selections, you might need to combine selections of the same material into one selection.
You might want to edit your UV map for the mesh too, unless you won’t use any textures or lightmaps at all.
2:
This is the more advanced method that requires some knowledge of how to use generate color ID maps and use them top create your maps for PBR rendering.
You’ll need some advanced UV mapping knowledge for this, since a good UV map is a key to success in this.
As far as optimisation goes, method 2 has far less overhead and will render faster in realtime but take up more texture memory, which might increase loading times a little.
Method 1 on the other hand is less efficient in rendering, since it increases the draw calls a lot, increases the number of materials and shader instructions and therefor reduces fps.
If you are planning to create an interior ArchVis Scene, you might be ok with M1, but for a game enviroment i’d recomend M2 for sure.
Also it doesn’t hurt to learn UV mapping and Material creation, since this comes in handy for a lot of purpose.
BTW: Cinema 4D has a very good integrated help manual.
To access it, just right click on something you want to know more about (e.g. the material Tag) and choose help from the context menue.
I’ve learnt a lot about 3D in general just by reading the C4D dokumentation pdf (long time ago).
Nowdays it’s all in the help menue, but still a lot of vital information.