That was the main bottleneck with my implementation of the signed distance fonts: a good font generator.
I got the source of the PXL fonteditor from ykot and planned to integrated the translated sd generation from a bitmap from the sdfont tool (from e.g. Cinder), but the signed distance font didn't scale well to small sizes, and the rush was high, so it went live with wglusebitmapfont fonts for (the one) small size, and only signed distance for big sizes. Unfortunately the only font that worked right was a bit cartoony, I'm not happy with it, but customers haven't commented till now (probably since they like the feature)
The problem is that the sdfont tool doesn't allow to specify a distance between the textures, packing them too tight which causes artefacts when rendering (or I'm doing something wrong)
I translated the C code during the christmas break, but then lost time again. I changed PXL a bit so that it can increase the distance between glyphs.
I also found a different algorithm for generating the signed distance glyphs that is probably faster. Must have a pdf for that somewhere. But in practice I plan to simply ship a texture in a resource anyway, since that makes things more crossplatform.
Even just creating a huge texture with a single, sharp glyph on it is hard, with the libraries available. And generating the signed distance textures from that on the fly takes too long.
Displaying the glyphs is easy.
Doing anything slow is easy. Doing it fast (like 15000 glyphs in <10ms) was the hard part. (building up the vertices is what eats up the time btw, not the GL part)
However, when I need to render small glyphs it is always in a small font, so I plan to do that with a separate draw step using a plain font atlas.
While the shader code will be much the same, the size of the vertices will be small due to the non scalability, and I hope that gains another factor 2.