Making a Physics Engine

For quite some time now, I've been intensely interested in the idea of building a physics engine from scratch, or as close to that as I could feasibly get. I can think of few projects more suited to both challenging and expanding my understanding of programming and physics than making a general-purpose physics engine. In my vision of the project - which I have called "The Djinn Engine", or just "Djinn" - it would be able to simulate a wide variety of physical systems, from simple pendulums, to complex planetary orbits, to (simplified) atomic models. So far, I have successfully implemented gravity, springs (and several variations of springs, such as the anchored spring, bungee, "fake" spring, etc.), and drag, with working demos for each of these forces. More recently, I have implemented collisions into the engine for particles (not yet rigid bodies).

A demonstration of the capabilities of Djinn to simulate gravitational bodies. Note that the relative sizes are to scale, and the distances between each body are to scale, however the distacnes are not to scale with the sizes. Future work on this demo would see this aspect fixed, however currently the limitation is travel time between each planet (and draw distance).

Although I have covered a good deal of ground in the relatively short time I have spent designing Djinn, there is still a lot of work to be done. To name a few things:

• Implementing more complex physics, such as electromagnetism as described by Maxwell's Equations
• Implementing more complex simulations, such as fluid dynamics
• Implementing a GUI for the engine, so that it can be used as a general-purpose physics simulator for non-programmers (as it stands, all demos are made by programming the scenes directly)
• A means to save and load previously-made simulations for continued work on them
• Converting my build process to CMake for easier porting to other systems than my own
• Reframing the engine in the paradigm of Lagrangian or Hamiltonian mechanics, or perhaps allow the engine to freely switch between them when convenient

Each of these examples presents an entire project in itself, so this will take quite some time, however I am more than OK with taking my time on this, frankly, massive project. I have a lot of fun working on it, and I am learning a lot about programming and physics in the process.

While I had some experience in C++ with my Mandelbrot Set project and working on PhoSim, that was about my only exposure to the language before I began making Djinn. In the process of making Djinn, I have learned a great deal about some aspects of programming totally absent in higher level languages like Python, such as memory management, pointers, creating robust Makefiles, and the like. I've also had to use external libraries to manage certain aspects of the engine that I've deemed not critical to the actual physics of the engine, such as graphics (Raylib) and logging (spdlog)

The full codebase can be found here on my GitHub.