Correct lines visualization.

OpenGL OpenGL: Advanced Coding
1

Visualization of lines together with shaded surface gave following results:[ATTACH=CONFIG]920[/ATTACH]

How to improve lines quality?

2

Use polygon offset to push the polygons backwards in Z:

glEnable(GL_POLYGON_OFFSET_FILL);
glPolygonOffset(2,2);
//draw surfaces
glDisable(GL_POLYGON_OFFSET_FILL);

You can adjust the variable and constant offset amounts sent to glPolygonOffset() to tune it to what works for your scene. I’ve found that 2,2 works quite well for my application.