seeing thngs in viewport like a rectangle why ?

see pic included

why do we see a rectangle in middle of face ?
[ATTACH=CONFIG]137042[/ATTACH]
thanks for any help

Do you have a .blend file to post?

Neil

ok here is the file showng this

[ATTACH]137105[/ATTACH]

It´s b/c of your wonky construction :smiley:

It is the plane from the other side of that part clipping through. It is on both sides.
Oh, and your normals face the wrong way too.

If you really need these to be coplanar, convert the front and back faces to triangles. If you don’t want to see the triangles in flat shaded mode apply smooth shading just to these triangular faces.

your right about the normal

as the faces are very close to each other it’s very difficult to see which side it’s going! LOL
have to remember that one !

but by flipping it looks like the rectangle dissapeared!

but i still dont understand why you see a rectangle in viewport only and not in render ?
seems to be a consequence of the normal somehow being the wrong side!

thanks