Simplified VT framework

[selden]

At the request of a new user of Celestia, I've tried to provide a simplified document describing how to use Virtual Textures. In particular, how to use VTs that consist only of Levels of tiles with no accompanying CTX or instructions.

Please take a look at the Web page
http://www.lepp.cornell.edu/~seb/celestia/brief_vt.html
and let me know how to improve it.

[John Van Vliet]

In particular, how to use VTs that consist only of Levels of tiles with no accompanying CTX or instructions.

That would be me