Hi everybody,
I just started to create games and I have some questions about the games performances.
I understand that I must use low polygon models to add details in the normal map.
Usually how much is the maximum number of polygon that can I insert in the map?
When I create a normal map is there some device that I can follow? Or can I do what I want without any problems with performances?
10K per character up to 4 characters on screen at one time and a total number of polygons in the game to not exceed 150K is the best with current common HW. There is help in the Unity Help pages if you take a look.
It depends on your target hardware and how much of whatever object you’re making is going on-screen. Gaming PC’s can push almost anything you can throw at them, but mobile hardware is much more limited.
That doesn’t even make sense.
Thank you for the replies 
I create a models and then I use mudbox and I sculpt it. In this way but the number of polygons raise very much, so I create a normal map that I use in unity to apply it on the original model that is a low poly. Is it correct? Or it make performance problem if I don’t pay attention to something? I Just started to do this so I’ m very ignorant
You need to retopologize / decimate in Maya, Maya LT, MAX, or Blender, take your pick. Create your textures before you do that and recreate you UVs after you do that is how it’s done. However you need to do a good retopo / decimate job to keep the low poly version from becoming a mess. Alternatively, you could poly model and sculpt just bits of detail (e.g. the philtrum, the hair shape) using subdivision surfaces to create the high detailed UVs textures and then export without subdivision surfaces.
Thank you so much, now all is right. If I want to create a character that user can costumize by choosing clothes, which is the right way?
If the closes have the same model, you can simply change textures or the material, otherwise you can exchange the whole cloth mesh.
I want to use different model for the clothes, so as to be more different between each other.
How can I change mesh without affect on the character’s animations?