Posted by Wade Walker on May 23, 2012; 1:31pm
URL: https://forum.jogamp.org/I-can-t-set-Line-Width-to-1-pixel-tp4004559p4008657.html

I mean, have you got full-screen antialiasing turned on via ARB_multisample (defined at http://www.opengl.org/registry/specs/ARB/multisample.txt, see http://nehe.gamedev.net/tutorial/fullscreen_antialiasing/16008/ for an example). This could give the appearance of line antialiasing, though I don't know why it would only work at some widths.

This could also just be a driver bug or bad line implementation in your graphics card. As I understand it, consumer graphics cards sometimes don't implement lines very well, since they're mostly used in CAD applications. You might try on another graphics card to see if you get the same results.