Billboards/Sprites
By Alan Baylis 15/09/2001
Using billboards is a very fast way to achieve halo effects, smoke, etc and before
having a look at my source in main.cpp I do recommend you read a tutorial by
Nate Miller on the subject. This example
uses the same method as Nate describes to make a halo type billboard that always
faces the camera no matter where the camera is positioned. There are also occasions
when you want the billboard to rotate to face the camera but remain vertical when
viewed from any position, when displaying fire or trees for example. For this
reason I've also included another method for making a fire type billboard which
works for a camera with 6 degrees of freedom.