Are there any cons to using multiple object in one static mesh for use in games?

danpos91

Hello - I'm working on a model at the moment and I'm still very new to all this.

I'm just wondering if when creating a model, are there any negatives to adding separate pieces of geometry to one model? Or should you connect everything up in the end?

antweiler

Do you mean to actually connect the geometry like merging vertices etc, or having pieces in your 3D App separated (like a character with a belt or necklace)? The latter should be no problem, i guess most engines create a combined mesh during the export process, and you keep a better organized sourcefile. If not, just combine your meshes just before exporting.

danpos91

Hi sorry I meant for example - you're modelling a house and you're at the windows. In Edit mode you could either create geometry around the window to extrude and turn into the window frame, or more simply you could just add a cube to the mesh, and make this into the window frame - so it's part of the house but no vertices are joined?

For single renders it looks really good but in terms of a game asset would it cause any slow down having unconnected geometry?

Eric Chadwick

No. As long as they share the same material.

You should delete any triangles that are never seen, like the outside of the window frame that touches the wall. These unseen surfaces can contribute to Overdraw.

Also be careful of z-fighting if you are using hardware with a low-precision z-buffer. Mobile for example.

Another consideration with not merging/welding the vertices, is they can cause more aliasing in-game. Some info about that here.
http://wiki.polycount.com/wiki/Normal_Map_Modeling#Contiguous_Meshes