Can anyone explain "normals of the two polygons should be adjacent."?

[Anonymous]

The 3ds max help article on Editable Poly (Edge) has the following in the first paragraph:

"Also, the normals of the two polygons should be adjacent. If they aren't, you wind up with two edges that share vertices." 

I searched around and haven't found any definitions of terms that will lead to understanding this. How can normals be adjacent (or not.)? How does a non-adjacent normals situation cause edges to share verticies?

Thanks

[10DSpace · Accepted solution]

Hi @Anonymous 

"Also, the normals of the two polygons should be adjacent. If they aren't, you wind up with two edges that share vertices." 

I have to agree with you.  This makes no sense to me either as written.   I would just move on to the more useful parts of the documentation and chalk this up to bad technical writing.  

[leeminardi]

I think "parallel" should have been used instead of "adjacent" in the explanation.  I'm not sure if the two normals should also have the same sense to ensure that there is only one edge between the vertices.

If the normals are parallel then the two adjacent polygons lie on the same plane.

[domo.spaji]

I'm not native english speaker but expression 'adjacent' is pretty familiar to me.

I think it's an 'official' expression as I can't think of others and can be found in any readings that matter...

If 2 polygons share an edge and you flip  the one face/normal they will continue to share vertices but not the edge.

2 "splited" edges will share those 2 vertices.

That's the expl. but best to try it yourself.

[jibijib]

Surely it means -cube on the left- and not -cube on the right-?

[Anonymous]

@10DSpace

Thanks! That's just what I did, but I always try to see if I'm just missing something. It really sabotages the usefulness of the "help" when something like that is right at the beginning and given equal importance with the most basic definitions and data.

[Anonymous]

@Anonymous, @domo.spaji, @jibijib

Thanks for your answers.

I played with flipping normals. It works on editable mesh - there is even a button that will flip one face. Each the of the faces have a different edge in the same place (clicking the edge shows the number, clicking again gives a different number.) HOWEVER I couldn't get editable poly to do this at all. Converting a mesh with flipped faces to poly resulted in the thing breaking into pieces.  So. I don't know what problem the writer was trying to prevent by putting this line in the help, and it certainly isn't something that should be in the first paragraph.

Thanks again!