TexFont (TXF) is a "texture mapped" font format, and associated software, designed to work well with the OpenGL API. It was developed by Mark Kilgard. It is presumably not related to TeX.
Files begin with bytes
0xff 't' 'x' 'f', followed by either
0x12 0x34 0x56 0x78 or
0x78 0x56 0x34 0x12.
- The TexFont software listed above includes some samples.
- A Simple OpenGL-based API for Texture Mapped Text (from archive.org)