I am currently creating a large open world map and have a question about creating buildings in a modular style. I was wondering whether using a modular style would result in too many draw calls. This is something I was informed of by someone I was working on another project with. To get a sense of what I am working with this is a modular panel http://i.gyazo.com/af0a46fc7f873c4be23c29f32610cb56.png . I would probably use about 6 of them on each side of a building. Other modular parts I would use would be roofs, etc. Sometimes I may even use a different modular piece for each floor ( would that be ok?). I suppose my question is would it just be better to create the building from modular pieces in the 3D modeling program and then merge them together as one object.
Thanks in advance.