Edit face's normal

Rigging
#1

Hi everybody
I wonder if there are anyway to edit face’s normal freely? Maya give us some option in Normal’s section like reverse, set vertex normal but they only working with vertexFace.
thank :D:

#2

I believe the face normal is calculated from the vertex face normals, I don’t think you can set it directly.

#3

The face normal is the normal of the plane defined by the triangle(s) of the polygon. It’s created by taking the cross vector the first two edges in the triangle, so it’s dependent on the order of the vertices. You can flip it - by changing the order of the verts - but you can’t alter it otherwise.

#4

Oh, i see. So that’s mean, it got calculated automatic and there is no way to keep it constant?
Btw, i’m tring to playing around with celshading since lighting calculating base on normal, right?
And thank for reply, guys :slight_smile:

#5

lighting calculations are usually done using the vertex normal, not the face normal.

#6

Yeah. The ‘maya’ way to manage these is usually to harden/soften edges, or sometimes to hand-set the vertex normals.

  • When you have a hard edge, maya will set the vertex-face normals adjacent to that edge so they match the face normals from which they come.

  • When you have a soft edge, the vertex-face normals adjacent to the edge are averaged.

  • Setting a vertex normal sets all of the vertex-face normals that come from that vertex, so it’s ‘smooth’ but not necessarily the average normal for that vertex

  • Setting a vertex-face normal implicitly creates a shading discontinuity at that vertex