font rendering in 3D technique

[Isaac Dupree]

This technique is memory/time efficient and simple enough that we could
figure out how to do it ourselves. It's also implemented in Qt 5's
scene graph, which we may or may not be able to leverage.

http://blog.qt.digia.com/blog/2011/07/15/text-rendering-in-the-qml-scene-graph/

which cites

http://www.valvesoftware.com/publications/2007/SIGGRAPH2007_AlphaTestedMagnification.pdf