Physics Engine

A simple 2D physics simulation written in C using SDL3. The simulation demonstrates efficient ball collision detection using spatial grid partitioning.

Features

• Real-time simulation of up to 10,000 balls
• Efficient collision detection using a 2D grid (spatial partitioning)
• Gravity toggle
• Adjustable simulation speed
• Ball spawning with random colors and velocities
• Window resizing support
• Visual grid overlay for cell partitions

Controls

• Left Mouse Button: Spawn 100 balls at mouse position
• Up Arrow: Increase simulation speed
• Down Arrow: Decrease simulation speed
• Backspace: Remove 100 balls
• G: Toggle gravity on/off
• P: Print ball count per cell to console
• ESC: Quit simulation

Build Instructions

1. The src folder (with SDL3 headers and libraries) is included in this repository.
2. Compile with a C compiler, using the provided SDL3 headers and libraries. Example (Windows, MinGW):

   gcc main.c -o main.exe -Isrc/include -Lsrc/lib -lSDL3

3. Ensure SDL3.dll is in the executable directory.

How It Works

• The simulation space is divided into a grid of cells.
• Each ball is assigned to a cell based on its position.
• Collisions are only checked between balls within the same cell, greatly improving performance.
• The grid is redrawn each frame for visualization. q

Gallery

(laggy due to GIF compression)

Issues

• The project is currently Windows only. I am working on making it cross-platform

License

This project is licensed under the MIT License. See the LICENSE file for details.