Unlocking vertex normals

[fubar3d]

I have a poly-shape, imported from CAD data.
The vertex normals are unshared and the values look all ok.
When I select all vertices and unlock the normals the actual values of the vtx-normals changes and the shading gets destroyed.

What exactly does "unlock normals" do?
What is the default state?
How is it saved with the object (what attribute) eg. in maya ascii file?

joerg

[jeffd]

A locked normal has a set value that will not change no matter what you do to the topology of the surface. An unlocked normal is calculated on the fly from the neighboring polys depending on the edge smoothing. If the edge is smooth the unlocked normal averages the connected faces normals for its value. If the edge is hard, the vert will have normal matching the face normal for each connected face.

--JeffD

[fubar3d]

If I understand u correctly, this means that maya saves for each edge the smoothing angle (or a group of edges).
And since unlocked normals will never keep the original normals from import they have to stay locked, which again means that working on the mesh (like freeze or merge vertices) will cause major problems...

DANG!

thx for the answers though =)

joerg

[jeffd]

Mostly right.

Maya doesn't save an angle for the smoothing. It only saves a smooth or not-smooth, on-off, for an edge.

Depending on how much work needs to be done to a mesh, you may or may not need to unlock them. Unlocking can be done per vert so it can be done in a localized area. I find that in general setting up edge smoothing isn't terribly time-consuming to re-do.

--JeffD