This was just discussed over here:
http://www.java-gaming.org/cgi-bin/JGNetForums/YaBB.cgi?board=2D;action=display;num=1106239125The precise formulas, however, can be found (with the explanation of how they are derived) in Chris Hargrove's Demo News tutorials. The zip file is here:
http://glstation.free.fr/mine/djgpp/tutor/dntut.zip(The DOC files inside are really text files, so don't worry about having Word.)
The forumulas he gives are:
NewX = (OldX*Cos(angle)) - (OldY*Sin(angle))
NewY = (OldY*Cos(angle)) + (OldX*Sin(angle))
For those who read my Robotron 4096 code, those formulas should seem familiar. After all, they're the same ones I used to rotate the 3D sprites into view. :-)