Face bending

[Klimat]

So I have a square face from picture “A”, it is automatically bend on a line between the upper and the left vertices. Let’s say I want my face to bend on the other possible line. The only solution I’ve found is to turn my square face into two triangular ones like it is shown on the picture “B”. But I also know triangles are pure evil, so I’m not really happy with this method.
Are there any other solutions to the problem?

[Sanctuary]

I don’t think it is possible without involving triangles, as Blender does not seem to support non-convex quads.
Either in the modeller or the renderer, it create the same ugly artifact you have in the screenshot.

Hopefully once BMesh is implemented , this kind of non convex quad will then be supported like it is in Wings3D