I should mention that panda contains some very old and probably broken portal code. However, personally, I feel that the whole portals concept is past its prime. It was really useful when games took place mostly in dungeons. But nowadays, almost every game has a few outdoor levels, and portals just don’t work for those. I don’t think it’s worthwhile to learn or fix the portals code in panda.
Instead, if I wanted to do visibility culling in Panda, I would first experiment with the algorithm described here:
gamedev.net/community/forums … _id=153497
Update: actually, I vacillate. Sometimes I think I would like to try out Coherent Hierarchical Culling. The downside is that it entangles the cull and render passes in a complicated way. In panda, these are implemented as separate passes.