Number of materials on a model

I am making a house inside and out in 3ds max. I first used regular uv maps to texture the walls and floors, but now im optimizing it, so im using render to texture. However as i go on im realizing that im going to have different materials for each room in order to keep the quality the way it was. How many materials is too much? Right now, not including furniture, i think i have around 8 materials for the house in total. This is my first time modeling such a large scene, and first time trying to optimize it, and im not sure how many materials is too much. Im targeting medium performance pcs, not iphone or mobile quality.

Another matierial usually means you also have that many submeshes. In other words, it’s the same as you had split your house into 8 seperate meshes. Each submesh will have it’s own drawcall. I don’t think there’s a submesh limit, but the overall vertex limit (64k) might give you problems, since if you use submeshes they all share the same vertex / index buffer.

Just for anyone who is interested. I conducted a stress test on a multiple range of iOS device. The first test was using a Single Mesh Model, the second was using a Multiple Mesh Model. Both exactly the same model, just combined mesh vs separated mesh, with a triangle count of 1,157.

The material being use was Unlit, so it was already very efficient to begin with. This is also running at maximum quality settings.

Both are pretty much very similar, although the Single Mesh performed slightly better than the Multi Mesh.