I would just directly ray trace it, no subdivision. Then it becomes something like 100 lines of code total, and is probably still faster than the subdiv approac

I would just directly ray trace it, no subdivision. Then it becomes something like 100 lines of code total, and is probably still faster than the subdiv approach. BTW I like to call that singularity at the pole god, because I often notice it in env maps as an arsehole in the sky :P