2D Physics Engine & Renderer Demo (C++ / SFML)

Overview

A real-time 2D physics engine implemented in C++17, using SFML for rendering and user input. Features:

• 2D Rigid-Body Simulation: Circles with mass, gravity, friction, and elastic collisions.

• Spatial Partitioning: Quadtree broad-phase culling for efficient collision detection (O(n log n)).

• JSON Configuration: Simulation parameters (gravity, friction, entity spawn rates) loaded from assets/config/config.json.

• High Entity Count: Can handle ~1000 entities at 60 FPS.

• User Controls:

  • P: Pause/Resume simulation
  • T: Slow motion toggle
  • Backspace: Clear all entities
  • C: Spawn random circle entity
  • Q: Toggle quadtree visualization overlay
  • F: Toggle FPS and entity-count overlay
  • H: Show help overlay with keybindings

• Dynamic Visuals:

  • Velocity-based coloring and random entity colors
  • Help overlay with semi-transparent background
  • FPS and entity count display

Demo

Building & Running

1. Install SFML (>= 3.0) and ensure headers/libs are accessible (may have to copy the SFML lib folder contents into build)

2. Clone this repo.

3. Copy assets/config/config.json to the build directory (handled automatically by CMake).

4. Build with CMake:

   mkdir build && cd build
   cmake ..
   cmake --build .

5. Run:

   ./PhysicsEngine

Project Structure

physics-engine/
├── assets/              # JSON config, fonts
│   └── config/config.json
├── include/             # Public headers
│   ├── Config.hpp       # Global constants
│   ├── model/           # Vec, Entity, Physics, Quadtree, Collision, World
│   └── ui/              # Renderer, Simulation, ShapeFactory
├── src/
│   ├── main/model       # Model implementations
│   └── main/ui          # UI implementations
├── CONTRIBUTING.md      # Repo commit style
└── CMakeLists.txt       # Build setup

Possible future improvements

• Resource Manager: Centralize loading of fonts and textures to avoid duplicate loads and manage lifetimes.
• Error Handling: Add robust checks (e.g., fail-safe on font load) and user feedback for missing assets.
• Code Organization: Introduce namespaces (e.g., engine::model, engine::ui) to prevent symbol collisions.

Next Steps

1. Finalize Pause/Help overlay polish and consider animated fades.
2. Implement Resource Manager for assets (fonts, textures) in ResourceManager.hpp.
3. Possible improvement to the UI

Reflection

The sole purpose of this project is to act as a stepping stone into 3D collision physics and rendering. I have learned so much about rendering, physics, and just generally how to solve issues in C++ with tools I have never even heard of before. While I certainly could have implement more, I really hope to venture out into the 3D world, and believe I have gained the knowledge to at least try. I am excited to extend my knowledge to 3D spaces, and I hope you enjoy this demo.