Strange Deformation With Brushes

I don't know if anyone else has notices this, I'm sure they ahve.

If for example I define a brush like so:


mBrushArray = new float[9];

for(int x=0;x<9;x++)
{
mBrushArray[x] = 50;
}
mFixedBrushScale = myScale;
mBrushScale = mFixedBrushScale;
brushArrayWidth = 3;
brushArrayHeight = 3;


Thats should give me a 3x3 brush with 50 in each element. The deformation should effect an area like this:


_ _
|_|_|
|_|_|

1 2 3
4 5 6
7 8 9


However, in the actual game the brush gives this effect:


_ _
/_|_|_|
|_|_|_|
|_|_| /

1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16

Vertices 1 and 16 are unused.


I have no idea first of all how an array of 9 floats is affecting 14 vertices and why it seem to skip the first and last, very strange.

Has anyone come upon this issue before?

So, its safe to say Im the only one with this problem? If tahts right could anyone point out if Im doing somehting fundamentally wrong with how i setup the brushes?

Nothing wrong with how you set your brushes. I think this has to do with the fact that the terrain is build from triangle strips. Try to write a simple program to render a small heightmap directly with OpenGl or DX and it will become perfectly clear to you... Sorry could have been more specific ages ago but I kinda forgot the details of the thing.

Ah, I understand now, it is affecting only nine vertices, but the other triangles are being strectched as they share vertices.