Scaling friendly font rendering with distance fields
As a bitmap font is scaled up, it becomes blurry due to linear interpolation. It is possible to tell the underlying texture to use the nearest filter, but the result will be pixelated. Additionally, until now, if you wanted big and small pieces of text using the same font, you would have had to export it twice at different sizes. The output texture gets bigger rather quickly, and this is a memory problem.
Distance field fonts is a technique that enables us to scale monochromatic textures without losing out on quality, which is pretty amazing. It was first published by Valve (Half Life, Team Fortress…) in 2007. It involves an offline preprocessing step and a very simple fragment shader when rendering, but the results are great and there is very little performance penalty. You also get to use smaller textures!
In this recipe, we will cover the entire process of how to generate a distance field font and how to render it in Libgdx.
