I've started a tutorial for Newtonian gravity in PDF format. I have the math and code written, and now I'm just fleshing it out with English:

https://github.com/sjhalayka/papers/blob/main/newtonian%20gravitation/bezier_escape.pdf

In the tutorial, I am covering the following topics:

• Typedefs and constants
• Brute force: integer field line count (glacially slow)
• Heuristic: real field line count (much faster)
• Modeling Mercury's orbit
  • Euler integration
  • Symplectic integration
• A final code: https://github.com/sjhalayka/mercury_orbit_glut

Is there anything else that you'd like to see in the tutorial?