A projectile simulator in C++17 that compares trajectories with and without air resistance. Built from scratch as my first C++ project — part of a self-directed path toward robotics.
simulation.mp4
| Metric | With Drag | Without Drag | Difference |
|---|---|---|---|
| Max Height | ~42 m | ~63.7 m | -34% |
| Range | ~109 m | ~163 m | -33% |
| Flight Time | ~4.6 s | ~7.2 s | -36% |
| Peak Time | ~2.69 s | ~3.6 s | -25% |
The drag case is noticeably asymmetric — the projectile climbs slower and falls steeper because drag is proportional to v², so it hits hardest at the beginning when speed is highest.
Gravity pulls down, drag opposes velocity:
Parameters used:
Integration is forward Euler with $\Delta t = 0.001$s.
src/
├── domain/ # Vec2, Projectile, forces (gravity + drag)
├── application/ # Simulation loop, IExporter interface
├── infrastructure/ # CSV file writer
├── main.cpp # Runs simulation → CSV
└── main_visual.cpp # Runs simulation → Raylib window
The domain layer has no dependencies on I/O. The simulation talks to an abstract IExporter, and the concrete CSV writer lives in infrastructure. This separation made it easy to add the Raylib visualizer without touching physics code.
Requires a C++17 compiler and CMake 3.20+. Raylib is fetched automatically.
cmake -B build
cmake --build build
mkdir -p output
./build/app # outputs CSV
./build/sim_visual # opens visualization windowFor the plot: python scripts/plot_trajectory.py (needs pandas + matplotlib).
This was my first time writing C++. I came from TypeScript/Python.
Things that tripped me up: the compilation model (headers vs source files, why you get linker errors), name shadowing between variables and functions (had drag as both a variable and a function — compiler was not happy), and figuring out CMake.
Things I liked: operator overloading makes physics code read like math (velocity + acceleration * dt), and the compiler catches bugs that would be runtime errors in Python.
This is checkpoint 1 in a robotics learning path. Next up: A* pathfinding, then PID control for a differential robot.
README written with AI assistance. Code is mine — written while studying physics simulation and C++ fundamentals through courses and documentation.
License: MIT