Sometimes APOCALYX users want to load ready-made Quake3 BSP levels without writing too much code, to see how they look like in the engine. Imagine several BSP levels stored in a single *.pk3 file, as usually Quake3 BSP levels are shipped. You don't need to write any line to see them, simply use the BspLevel.lua demo included in DemoPack0
BSP level from the "Q3 Rally" MOD
At the beginning, the BspLevel script, looks for the file pak0.pk3 and lists all the BSP levels included in it. Then the user can choose one of those levels and the avatar (the well known Wrokdam model) will appear in one of the spawn points. Use the DEL key if you want to free the camera, when the avatar is teleported in places where the geometry prevents it from moving.
Usually the levels don't look as in the original Quake3, because of the limited support of Q3 shaders, but some are not so bad. Since transparencies are disabled in the script by default, try also to enable them pressing the "T" key (as explained in the help screen).
In conclusion, if you want to view levels taken from the Quake3 MODs, simply put the original *.pk3 file, containing the levels, in the engine folder, then rename that file to pak0.pk3, execute BspLevel.lua and choose a level. Probably you'll find one that looks good enough to be used in your own demos, without losing time in the modelling phase.