Guns flicker and light weird after BLENDER edit

[Odinml]

After i edit some guns in BLENDER they flicker or light funny, and all the pollygons are lit diferently, why does it do this and how do i fix it? its realy putting a damper on modding my weapons any help would be greatly apriciated.

[Ghogiel]

and all the pollygons are lit diferently,

without pics, only that part of your description caught my eye.

 

possibly you removed any face smoothing. I believe hard shading this is called in blender. ideally you don't want soft shading either...

 

the normal maps for the vanilla weapons were baked with specific hard edges on the low poly models. it is best to try to preserve that as much as possible. or else you will get shading errors. you should be able manually set those up quite quickly and easily.

[ecksile]

I was thinking the same thing that combined with a not to well done alpha map can cause some nasty looking stuff on your guns. Good alpha map or not its still gonna do it. The funnest thing about this little problem is you get to go through the entire model and decide whats gonna look round and whats gonna have hard edges etc..in my opinion when done correctly it looks much better then most of the guns on nexus which have no smoothing applied at all and round objects have hard edges. But there is 1 problem in this as well. You will sometimes get smooth errors where attached geometry will "shade" funny and for this you have to apply edge split modifier to get it looking decent but then you have to rework the smooth parts and its fun =]. Id post up some screenies of what im talking about but i gots jury duty in a little so maybe later if you want.

[Ghogiel]

the only reason there are hard edges on weapon nifs is because they are using tangent space normal maps and not object space. often unless there is a chamfered edge on those 90 degree parts of geometry the bake won't come out and you'll get smoothing errors. as those types of normal map often can't cope with bending the lighting that much. object space normals look pretty much better in everyway in this regard and are much more accurate- I haven't been able to get any to render in F3 yet... otherwise the meshes could be completely smooth shaded and the normal map would take care of the hard edges, and render pretty much exactly right.

 

the solution is to either use a hard edge and split the UV island, both of which increase vertex count. Or chamfer the edge, which increases the vertex count about the same amount, but also adds some extra faces as well. Either way are viable solutions to face normal shading problems and tangent space normal maps. imo really depends. if you look at the weapon models you'll notice a kinda mix between the 2, where key faces are split, but then there are some smoothed faces that look hard edged because of the normal map.

 

I've managed to get passable results from 100% smoothed faces and the normal takes care of the hard edges. though looking back on them, I would have stratigically placed some hard edges and split those UV islands, and I think I would have a cleaner result.

 

this is something that isn't well understood but the information is out there is you look. I recomend polycounts wiki on normal maps- its pretty much the best collection of info on the net http://wiki.polycount.net/Normal_Map