I am not sure I can state this problem correctly; there are situations in which I get graphical glitches when using a terrain made of triangle sectors with height (floor for instance) vertex things. Sometimes when you have certain.mm... geometric configuration of these triangle sectors some of the triangles do not render if you look from certain point of view, commonly (but not always) almost from above (it looks like texture simply dissapear and you can see what's beyond them).
This happen when I use OpenGL, Direct3D and software renderer as well.
So, I was wondering, what may be a reason of this? Can this be a problem of my graphics driver, or maybe engine has some limitations to how those triangles can be done?