What do you exactly want as shader ? 

yeah text command slow down the program a lot. But in comparaison of th texture routine, it's almost nothing 

good guess 

One variable who increment in the main loop, and every second, I save it and put it back to 0. Every frame, I display the saved value.

The end of the world

How can we still go to omni if the end of the world happen ?

I dynamic light depending of the view point, and I reuse part of backface culling

Just a little post to tell you my progress.

I have currently a basic light engine which work fine (It a little slow, however ) , and I start the portal things 

MEGA UPDATE OF THE DEATH !!!!    

I splited the librairy in two part, mostly to decrease the total program weight
GCORE : the main lib, contains most of basic 3d function
GPOLY : the polygons handling lib

I simply rewamped all the librairy. Polygons gestion is now a LOT better, as well as 3d processing.

A lot of things is planed :
A GOBJCT lib, to have an object gestion
GPORTAL lib : portal rendering !
some new function in the GPOLY lib...

I you have any problem, just ask me.

In the zip, you can find:
prgmGCORE and prgmGPOLY, the lib
prgmGEXAMPLE : GPOLY lib example
prgmGCUBE : GCORE lib example

compile with  axe 1.2.1a !

Last thing to say : I have not fully tested all the commands, so there can still bugs.
MAKE SURE TO BACKUP ALL YOUR DATA BEFORE USING GLIB !

I simply perform the normal vector of each faces using a cross product. With that, I have the plan equation of the face, and I check the camera pos according to this equation. The result is positive or negative, and I hide face according to data definition. The only thing that we have to worry is  when all the points of the face is not on the same plan (sqare only), but one workaround is to increase geometry complexity (or simply be careful)