new gamemode - keep the base [source included!]

[Luc@s]

I need help :D
I'm trying to draw a cylinder (with no bases, like a pipe so).
I made something but it doesn't work really well.

Look :

It first seems to work like I want :



But I can't see the full cylinder when I'm outside


And I get strange glitches


I tried to change glDepthFunc type, but it didn't work... :/

Does someone have an idea ?

Here is the code
cylinder function
cylinder call

Thanks ;)