Normals

[Obunako]

I always work with one normal associate with a polygon, but 3ds format export one normals for each vertex :blink: I don't understand, some one help me ?

Thanks.

[Dia Kharrat]

Yes, it's possible to have a normal for each vertex. This is done for lighting calculations. If you find the normal to a triangle, you are finding a "Face Normal". If you give OpenGL a face normal for lighting, it will make your object look really flat and not very round. If we find the normal for each vertex, it makes the smooth lighting look. This also covers up blocky looking objects and they appear to have more polygons than they do.

[moomin]

per vertex normals are teh w1n!!!!


Render a sphere with per face normals, then

Render a sphere with per vertex normals


the difference is amazing.


That reminds me how many of the neighbour face value normals should I use to calculate the per vertex value?

[anubis]

imagine it like this :

you find per-polygon normals for each polygon in your model. obviously this will result in surfaces that will look very flat when lit as apex said. the easiest way around this is to average the normals of faces that share a vertex. you then assign this new averaged normal to the shared vertex and thus get a different normal for each vertex instead of one for each face.

result == smoother shading.

[davepermen]

How to do it (http://www.devmaster.net/forums/index.php?showtopic=414)

[donBerto]

davepermen: a VERY nice example.

:yes:

[davepermen]

thanks