Thanks, now I understand it!
> The problem is that GL_*_SMOOTH have dodgy implementations on non pro > hardware. Most card only implement 1 pixel wide smoothed lines, and most > don't even support GL_POLYGON_SMOOTH. > For more info about texture based antialiasing you can check out: > http://homepage.mac.com/arekkusu/bugs/invariance/TexAA.html > Sebastien