   Batch Rendering Confusion
  First let me point out that I'm an artist who only dabbles in graphics programming.  I know how to write basic HLSL, but I am by no means a programmer.I'm trying to figure out how to best build assets for the engine we are working with which uses Batch Rendering.Basically I have two buildings that share 4 textures, but that each have 1 texture unique to them (an ambient occlusion map).  I am wondering how the introduction of the ambient occlusion texture into the mix affects performance.What I am basically asking is that do I lose the performance benefit of batch rendering if all my textures in a material are not identical?I know this is a really basic question to be posting on a programming forum, but I figured this community would probably be a good place to find an answer.Thanks in advance for any help :)
  The answer is "probably" :)If using DX10 or later, textures can be indexed so you could reference both the AO maps from the one shader which keeps you able to render multiple building instances with one draw call and some halfway clever setup.Chances are higher though that your engine won't support this (If WinXP, then DX9, then no texture indexing) but you can still get multiple instances from one draw call if you can put both AO maps into the same texture and reference them differently (ie using a vertex component as a UV offset in the second building.All of the above requires setup code in the program, so if you're not been told about this then you're probably not gonna get it tbh. Either that or your programmer needs to learn how to spec out art rules better. :)The simplest system would indeed require a drawcall per building with totally separate textures as you intimate. And given what I said in the previous paragraph this is probably the system you end up with. Unless you're rendering 100's of buildings though, I doubt it will be a problem.   ;  Best answer I have gotten, thank you so much.   