Normals generation questions

[Gildor]

First of all, Unreal does not operates with PSK data, it uses different and more complex internal mesh format. PSK is just a format used by Epic Games to export data from modeling software to the game engine.

UE3 mesh has normal, tangent and binormal data stored in the mesh, because normal generation is relatively slow process, and engine programmers decided to store normals in packages instead of rebuilding them every time. Current version of the umodel uses this data for rendering, but older versions used this information, so I have functions to compute mesh tangent space. This code is used for UE1/UE2 meshes now. To share normal between wedges I'm analyzing "Points" data - each wedge has an index for vertex position in "Points" array. When 2 or more wedges shared the same "point" I'm smoothing normals between them (they will share normal which is computed from the normals of adjacent triangles), but when wedges uses different "point", even when position is exactly the same, normals will not be shared.

Tangent and binormal are computed with use of the vertex normal and information about UV coordinates of other vertices in neighbor triangles. Algorithm is my own, but I don't think it is something "unique", it is quite simple task.

There is a small difference when I'm using precomputed normals/tangents from Unreal data or when I'm computing them. It is not significant enough to change my algorithm.

I hope I did answered to your question. If no - feel free to ask other questions.

[Gildor]

Sorry, umodel can export into psk or md5mesh formats only, both formats has no place for normals.
By the way, "original normals" are also generated by Unreal engine, because most meshes were imported using the same psk format. Only recent UE3 versions has FBX support which could hold normal data as well.

[Gildor]

That's a nice hobby. I had the similar one before started to work on umodel.