More Texture Mapping

Very good read and easy to understand. Beyond the basics:

http://www.informit.com/articles/article.aspx?p=770639&seqNum=4

Perspective Correct Texture Mapping. Back to basics of U V from X Y
http://easyweb.easynet.co.uk/~mrmeanie/tmap/tmap.htm

Some simple TRIGO maths:

http://www.ies.co.jp/math/java/trig/