I was recently trying to implement text for the graphics engine behind Omber. Unfortunately, although I had a complete vector graphics engine, I hadn't gotten around to implementing support for shapes with holes in them, so I couldn't just take the vector representation of each font glyph and render them directly. Instead, I ended up using the standard approach used in many 3d game engines, which is to use Signed Distance Field fonts.
Most people pre-generate their SDF textures, but that didn't really seem feasible to me. I wanted my code to let people use their own fonts in their drawings, so I couldn't precalculate SDF textures for those fonts. Also, international fonts might contain thousands of characters, and it would be too memory intensive to calculate textures for all of them in advance. So I went about trying to figure out how to generate my own SDF textures, and I learned some good lessons about how to do it.
At first, I didn't really understand how SDF worked, so I tried using the dumb approach of drawing a character on a bitmap, and then manually trying to calculate the SDF values. This actually takes a bit of time to code up, it's really slow to run, and the results are sort of poor. I didn't really understand that the shader really only cares about SDF values for the one or two pixels near the edge of a glyph, and the SDF values need to have subpixel accuracy. True, you might see some demos of people adjusting SDF cut-off values to make variations of a font with different font weights. But for normal situations, you only care about SDF values within a pixel or two of the edges of a glyph because when those values are linearly interpolated, you get a good approximation of the angle of the edge in that area. And you really do need subpixel accuracy or your linear interpolation will simply give you back your chunky pixels. To get that sub-pixel accuracy using a raster approach, you would have to draw your glyphs at a really big size and then scale the bitmaps down, but that's even slower and you lose a lot of accuracy.
So, yeah. Calculate your SDF textures at runtime straight from the vector representation because it's not much code and it's faster.