Modern opengl (core profile), the line width is limited by system. In order to draw a free width line smooth, we draw multiple triangles to construct a thick line. pyopengl implmentation is at github: https://github.com/stonewell/code-snippets/tree/master/opengl%5Fthick%5Fline

In modern opengl (core profile), there are a lot of tutorials on how to draw a circle using fragment shader, but most of lack of source code and only show how to draw at (0,0). This code piece draw circle at given center point with specified radius. pyopengl implementation is at github: https://github.com/stonewell/code-snippets/tree/master/opengl%5Fcircle

Rendering 2d text with opengl, either using bitmap font or freetype library