Yeah. It's all... glowy and smudgy, for various in-retrospect-obvious technical reasons I won't go into here (though if you're thinking to yourself "I wonder if a texture would get blockier as it's downsampled" you've pretty much got it) and I have little control over its appearance. The tutorial I've been using points out that an additional step can be used to separate out the stuff that should glow from the stuff that shouldn't based on its brightness, and then they can be mixed for an HDR-like effect. I may give that a shot just to see what it looks like, since I've already got the infrastructure written, but honestly I don't think I can get the results I want from this process. I'm going to have to go back to manually drawing the glows around the lines, even though it's substantially slower.
The benefit of all this work? Well, I have the basis of shader support in the engine now, in case I think of something else I want to do with it. And I do at least have it rendering the game to an offscreen texture before displaying it directly, which means I should in theory have more control over how the blend settings take effect. Plus, I know a bit more about how OpenGL textures work, which may help with the glow effects. So it's not wasted effort by any means, but it would have been nice if it had Just Solved All My Problems. Oh well.
One really annoying thing about all this is that I haven't been able to find any useful web resources for people who are replicating the look of classic vector graphics games. The main problem is a) that's a tiny, tiny niche and b) that style of game doesn't have a meaningful name besides "vector graphics" which of course produces about a million unrelated search results. Don't suppose anyone out there has heard of something...?
In other news, I realized that creating a wiki for the Neon Galaxy documentation was really overkill, as all I actually wanted to do was write some simple HTML. So I downloaded Komodo Edit and just got 'er done. That's a neat little editor, incidentally! For a programmer-oriented HTML/XML editor, it's hard to picture how you could do better.
Edit: Hmm. If I can get less blocky results, this just might be worth another try.