However over the last week I've been tinkering with shader stuff, with some interesting visuals. [grin] First was procedurally generated electricity arcs, but powerful though GLSL is, it's just not good enough to get proper branching arcs like I'm after. And it seems silly to limit it to higher end graphics cards for what can be done on the CPU very easily.
So I've revisited glow/bloom again. Before I'd done this with lots of passes and 2 texture units, but this time I'm doing it with 8 texture samples per pass (and as many passes needed based on the blur kernel). Just for the heck of it you can see bloom with a 16x16 blur kernel - which takes just four passes.
This is performed on a 256x256 texture and then streched over the whole screen - this keeps the fillrate lower and provides a little extra bluring cheaply. Realitically this is way over the top, with some better chosen weights I should be able to get away with an 8x8 kernel.