OpenGL - Lines

The default line width is 1 pixel. You can set it as you want by
glLineWidth(2.5);

To make the line smoother, use
glEnable(GL_LINE_SMOOTH);
This command makes your line bolder.

To create a dashed line, try

glEnable(GL_LINE_STIPPLE);

Then make the line
glLineStipple(1, 0x33ff);
The above function is glLineStipple(factor, pattern)


See more on: http://glprogramming.com/red/

OpenGL - Lines