Particle Simulation

2D particle simulation in C++ and SFML 3. Verlet integration, grid-based collisions, circular boundary.

20,000 particles at 60 FPS. Machine specs:

CPU: AMD Ryzen™ 7 7840HS, GPU: RTX4060, RAM: 16GB

Demo.mp4

Features

• Verlet integration, 4 substeps per frame
• Particle collisions with mass and restitution
• Uniform grid broad phase: each particle is only checked against its neighbours
• Circular boundary
• Particles spawn from the center, click to add more
• Gravity in 4 directions
• 1 px particles drawn as soft textured quads for a liquid look
• One vertex array, one draw call
• 5 themes, switchable at runtime
• Live particle count and FPS

Controls

Input	Action
Left mouse button	Add a particle inside the circle
Arrow keys	Set gravity direction
1-5 / Numpad 1-5	Theme: Ocean, Lava, Clean light, Neon, Mint

Build

Requires CMake 3.28+ and a C++20 compiler. SFML 3.1.0 is fetched automatically if it is not installed.

cmake -S . -B build
cmake --build build
./build/bin/particle-simulation

On Windows: .\build\bin\particle-simulation.exe

CMake copies ARIAL.TTF next to the executable.

Structure

include/
  constants.hpp         constants and themes
  particle.hpp          particle
  verlet.hpp            Verlet object
  solver.hpp            physics and collisions
  grid.hpp              uniform grid
  renderer.hpp          rendering, FPS and count text
  ISimulation.hpp       simulation interface
  circleSimulation.hpp  circle scene
source/
  circleSimulation.cpp
  solver.cpp
  verlet.cpp
main.cpp
CMakeLists.txt
ARIAL.TTF

Configuration

Everything is in include/constants.hpp: FRAME_RATE, SUB_STEPS, MAX_PARTICLES, GRAVITY, COR, CIRCLE_RADIUS, VISUAL_SCALE and the themes.