# Strange Vertex Count for a plane.

Hello

I’m playing around with vertices in the game engine, and there is some things that are odd to me. Especially with the number of vertices a plane has.

With a basic plane made of one face, the getVertexArrayLength() fonction prints me 4.
If I extrude an edge along one avis, I still have a plane with two faces, but this time, the function getVertexArrayLength prints 8.

If I try with a grid of 10 by 10, I get 122.

There is something I don’t get there… how much vertices does a square plane made of (9x9) 81 faces should have? If vertices can belong to more than one face, then it should be 100. And if not, it would be 4 vertices per plane, so 324…
Where does this 122 come from?

Update :
I’ve build up a little script that “parses” the vertex list taken from the plane and checks for vertices that have the same X and Y coordinates. It then moves the duplicates along the Z-axis. It also outputs the total number of vertices and the number of duplicates. It’s the best way I could find to visualise this “problem”. But it doesn’t help me to understand why.

You can get the blend file here: http://juego.free.fr/blender/vertexcounter.blend

Thanks for the help.

Ju

Hello again

Without any answer on this topic, I solved my problem by creating a plane from scratch with a Blender script (thanks to the tutorial at blenderpython.org).

So I generate a square “grid” plane, made of 9 by 9 faces, using 10 by 10 vertices (wich makes it a total of 100 vertices). Vertices are now ordered and (except the border ones) are attached to 4 faces. No ovelapping vertices anymore.

I still couldn’t find any information on this “noisy” subdviding tool and why it generates a strange vertex count (even if the mesh looks alright). The extrude tool also generates strange extra vertices. Any information regarding this topic will be greatly appreciated.

Thanks.

Ju