Source code for the Processing Core and Development Environment (PDE)
I've found processing.org, I think this is probably close to what I'm looking for but I wonder if people know of any others?
NOTE: The number of mentions on this list indicates mentions on common posts plus user suggested alternatives. Hence, a higher number means a more popular project.
Lines that keep going but never touch.
1 project | reddit.com/r/learnprogramming | 27 Jun 2022
Particles letter animation
1 project | reddit.com/r/processing | 27 Jun 2022
help me learn how to code please
1 project | reddit.com/r/software | 24 Jun 2022
Program similar to Arduino IDE
1 project | reddit.com/r/arduino | 13 Jun 2022
How does code translate to a game?
1 project | reddit.com/r/gamedev | 12 Jun 2022