Tweaks

Minor tweaks of late.

Restructured the rendering quite a bit. Keeping things very, very simple still: the rendering thread owns a list of functions that execute each frame, in the order in which they were added. Dumb as a pile of bricks, and assumes that each such render-function will actually do a bunch of stuff including culling.

Originally the rendering functions were all nullary and their results discarded. I swapped this over to each taking a single state argument, a hash map of arbitrary rendering guff, and each returns a (potentially modified) state blob. So the core of the rendering loop is a nice, cuddly-ish^*
(reduce (fn [s f] (f s)) initial-state render-funcs).

Right now the uses for this blob are limited. I'm just bunging a few things which were previously updated from different threads in there, such as camera data (ad-hoc derefing of atoms and such gives inconsistent rendering and general ickyness). So it's more like a way to carry around an immutable copy of the game state as of the start of the frame than anything truy useful. Suspect it'll be handy later to mirror the GL state and avoid heavy state-changing operations where they're not necessary, do pre- and post-invariant checks and other contract-y things, accumulate frame stats such as objects rendered... stuff.

Image is just some randomly coloured lights scattered around, this time with a bit less gloom. Still quite gloomy. I find myself wondering if it might be better to work with entirely solid hexagonal prisms as a starting point, rather than more elaborate geometry. Hmm.

---

* Cuddly-ish, but not very cuddly. I would really rather use something like (flip apply) instead of the embedded anonymous function, but cannot quite seem to conjure the right way to do this without doing something slightly horrible. Will look at it later with fresh eyes and doubtless slap my forehead at my own stupidity.