Normal Map everything?

Spawd

I'm currently working on a 3D game environment. Should I normal map everything or leave some things without them?
Do they have a impact on performance?
If I've got some barrels and crates lying around, should I normal map each one of them to get the texture and smooth edges?

Larry

If there is no detail sculpted on them why would you use a normal map? Textures cost more than geometry. Also, if it is the same crate and barrel , why place different normal maps? Just place the same everywhere

EarthQuake

If the object is perfectly smooth, it generally will not need a normal map. If an object has surface variation of any sort, a normal map is desirable.

Something like a crate will generally have wood grain, knots, chips, nails or screws, and various other surface details that would benefit from a normal map.

Whether you create a high poly mesh and bake a normal map is another question entirely. This depends on a number of factors, how much time you have, how important it is, and of course how it is UVed. If you're planning on using tiled textures, obviously you wouldn't create a unique highpoly mesh and attempt to bake a normal map, as it would not fit the UVs. However, you may want to make a high poly mesh to generate your tiling texture.

poopipe

Unless your shader system knows you've not added a map and adjusts itself accordingly  you're going to be paying for the normal map in terms of shader complexity anyway. 

 I wouldn't drop them for performance reasons - I'd drop them cos I didn't want to spend the time making them or at a push cos I needed to save memory ( whether it does or not will be dependent on how your shader system behaves)