This is really neat. Though in practice if you are using this kind of thing I'm pretty sure you will want to combine it with atlasing (i.e. construct an atlas of glyphs via render to texture). That's because it's a waste of time to rerasterize glyphs in the FS every frame (which appears to be 200+ lines) instead of caching the results and reducing the per-frame work to a 5-line FS that just blits. In most apps pans a…
This latter bit is exactly what modern 2D display drivers already do, or at least what the NVIDIA binary X driver does. It keeps a glyph cache in video memory and just blits from it to the extent that it can. It's still counting on the software to do the rasterization though, and I don't think there's a way to do the rasterizing on the GPU and then feed that data straight into the glyph cache.