I'm modeling with Studio Max, and there doesn't seem to be a feature for this. Or I just can't find it. What I'm trying to do is export a mesh in seperate parts. To do this, all I need to do is delete some polygons, export, undo, invert the selection, delete, export. Or at least it would be that easy if I could prevent the normals from being effected when I delete the polys. For an example, if I were to create a sphere and want to export the top and bottom half into two seperate mesh files, then render them as a single object in my game. If I do this, there is a horrible hard edge around the seem because of the normals edging off where I split it. I don't want to slice or anything complex. Just delete polys and prevent Max from changing any remaining normals. Is this possible? If anyone uses another modeling program, it would be great to know the name of the effect or modifier in that program. Maybe it would help me find something simular in Max. Thanks for help

im not exactly sure, but seeing as how normals are only a perpendicular line relative to a polygon's surface, wouldnt it be hard to have a normal without a polygon to be bound to?

Vertices contain normals, not polys. When two polys are weilded together, the vertices they share compute the normal by averaging the poly surface directions. I want to delete one poly but have the other one keep it's averaged normal.

And by one, I'm meaning a much larger scale. About 20 vertices on each seem, and about 12 seems per model. This is more about telling Max to not do something rather than having it work harder. If it's not quick and effortless, it's not worth it.

Thanks for the attempt

Wow. That's a tough one. Took a lot of tinkering to figure it out.

Here's how to do it (apparently this only works on edit mesh, so if you're using edit poly switch it over beforehand):
1) Put on an "Edit Normals" modifier.
2) Choose Select by: Vertex
3) Select all the verticies that you need normals to be preserved on.
4) With them selected, click "Make Explicit"
5) Put on an "Edit Mesh" modifier.
6) Delete the unwanted faces.

Because the normals are set to explicit, they should remain the same.
Hopefully whatever version you're using has all this available (I figured it out on v7). I suspect it will since I had to use Edit Mesh and that hasn't changed much in a while.

Did you test this out? I've tried to do this, and I can't get it to do anything. I applied Edit-Normals, selected all of the normals in the mesh (with select-by-normal on), clicked "Make Explicit", applied Edit-Mesh modifier, selected some polys, then pressed delete. The normals on remaining polys are still changing as others are removed. Edit-Mesh seems to completely ignore the Edit-Normals modifier below it. The docs say that edit-normals changes are sustained even through a stack collapse. I can't even keep it sustained right under the active modifier.

If this worked for you, maybe I need to adjust a modifier setting or change an option?

I should probably also mention I'm working with a skin mesh. I don't know if Physique will make it even harder to do this or not. I'm trying to do this with a static mesh now, though, until I can get it to work. Then I'll fight with physique.

Thanks a lot

Yes I did test it.
But now I've tested it in an older version (v5) and it does not appear to work.
Ah well, I tried.

It works fine in max7 that way.
I made a sphere
editnormals
hit select all
hit explicit
edit mesh, delete half the sphere
normals stay correct.

Its interesting to revisit this, because ages ago on a game project
we had to get around this when we needed seperate objects
but continuous normals for reflections.....