topic Re: How to properly set vertex normal in an editable mesh in 3ds Max Programming Forum

How to properly set vertex normal in an editable mesh

Anonymous — Fri, 16 Sep 2011 19:02:20 GMT

Hi, I was trying something simple. Change the vertex normal in an editable mesh.
At least I thought it was simple. Here it is:

- Start a new scene
- Create a sphere in , 50m of radius and with 10 segments
- Convert the sphere to Editable_Mesh
- With Maxscript, I am trying to change the normal for vertex index 3
- First, read the normal for vertex index 3
- Second, set the normal to something else
- Third, read the normal for the same vertex, to be sure it changed
- Update the mesh
- Read the normal again. This time, it's back to the original value

In Maxscript editor:

getNormal $Sphere001 3 --The result will be
setNormal $Sphere001 3
getNormal $Sphere001 3 --The result will be as expected, but no changes in the viewport
update $Sphere001 --To update the mesh
getNormal $Sphere001 3 --The result is the same as the original normal

I am probably doing something wrong and forgeting something.
Any help is very appreaciate.
Thanks in advance.

Re: How to properly set vertex normal in an editable mesh

Anonymous — Mon, 19 Sep 2011 12:19:45 GMT

Maybe I am wrong, it's just an idea, but can you really set the normal of a vertice ?
I thought the normal of a given vertice was "by constrution" the mean value of the normals of the "associated" faces.

-amarhys

Re: How to properly set vertex normal in an editable mesh

Anonymous — Mon, 19 Sep 2011 18:29:00 GMT

And you are right. The vertex normal is the result of all the adjacent face normals and smooth groups.
But Maxscript help states that one could change the vertex normal using the following line:

setNormal "mesh" "vert_index_integer" "point3"
Sets the indexed vertex's normal vector.

You would find this under Mesh Vertex Method.
But it's not working for me.
I thought the principle was the same as using the Edit_Normal modifier.

I am trying to get an answer from Autodesk about the reason, why this line of code doen't work.

Re: How to properly set vertex normal in an editable mesh

RaduCosma — Sun, 31 Mar 2013 16:53:37 GMT

Two and a half years later... (sorry for the bump btw)

Is this ever going to be fixed? SetNormal and setFaceNormal have been broken for god knows how long.

My friend and I are working on a geometry generation script and would really like to automate normals as well.

P.S. I know vertex normals can be set with the Edit_Normals modifier, but it's very very slow.