Still haven't looked into mzxrules' actor definition comments and improvements. At least this time I've got an excuse for that; don't have cold water in the bathroom since the weekend, water comes gushing out of the main valve for that when opened and drips out even when closed. Haven't slept very well since, haven't slept last night at all, fearing it might break completely (I mean, I sure as hell don't want water damage or something in here!). No toilet flushing, no washing machine, couldn't yet reach house management for them to send a plumber or something over.
Anyway, I have worked on SceneNavi a bit earlier, regarding alternative combiner emulation. I've more or less ditched the idea of doing it with glTexEnv (too limited and IMO not very intuitive), so I've started looking into GLSL, which is supposed to be supported on reasonably modern Intel hardware. I'm trying to target the lowest GLSL and OpenGL versions possible (1.10 and 2.0 respectively), too, so that there's a higher chance for this to work on lower-end chipsets.
It's still super-early work in progress - in fact, I'm not even parsing the actual combiner setups yet! - but even with some pretty simple "default" shaders, things look... reasonable already (check out the grass!):
For comparison purposes, here's the existing ARB_fragment_program combiner:
Still, no guarantees this'll work right on Intel GMAs, Intel HD Graphics, etc., I don't have (nor do I want) one of those to test things on.