Backface drawn last?

[Ghley]

I'm sure this is a common problem and has been solved several times but I'm unable to find a solution, I guess I'm just using the wrong keywords...

I don't even try to explain it a picture will clear it up, these are two cuboids constructed out of triangles

any idea what is wrong here?
Ghley

[Ghley]

problem solved, forgot to enable depth_test

Ghley