Separate UV for Normal map

unstoppablex

I was just wondering if there is any disadvantage to creating a whole new UVW for a normal map? example. UVW 1 is diffuse, UVW 2 is lightmap, UVW 3 is normal map.

The reason i think this is very useful is because some objects you create may need a normal map in some areas, but most areas of it is smooth or flat, and requires no normals. so adjusting a new UV with the faces that do need normals, would save you tons of texture memory.

what do you guys think about this idea?

Scruples

Crysis 1 did this for their nano-suit iirc, as long as the amount of tiling is similar I don't see any way it would affect performance discernibly. I assume 3d painting programs like 3dcoat and bodypaint would have issues displaying the normal map and diffuse map for painting at the same time, and painting would be a little harder.

Computron

It depends on your engine and the asset. some engines have to render the model one time for eacgh UV Set, some have other weird workarounds. Its somethings that needs to be balanced.

If this is for a portfolio, just worry about getting a good result. Resolution doesn't matter as much.