A real-time physics simulation (taken from this Linkedin post) of cloth, written in C++ using the SFML library. The project implements a "Mass-Spring" model managed via Verlet integration to efficiently calculate positions and velocities.
The code does not use explicit velocity. Instead, it stores the current position and the previous position.
- Verlet Integration: The new position is calculated based on the difference between the current and previous one (inertia).
- Constraint Solving: "Links" (springs) force points to maintain a fixed distance. If they move too far apart, they are pulled back; if they stretch excessively (5x), the link snaps.
| Constant | Value | Description |
|---|---|---|
WIDTH |
70 |
Horizontal Resolution: Defines the number of particles along the X-axis. |
HEIGHT |
45 |
Vertical Resolution: Defines the number of particles along the Y-axis. |
DISTANCE |
18.0 |
Resting Length: The default structural distance between connected points. |
GRAVITY |
0.35 |
Vertical Acceleration: Constant force applied to the Y-axis of every point each frame. Controls the perceived weight and "heaviness" of the fabric. |
AIR_FRICTION |
0.98 |
Damping Factor: Represents air resistance and energy loss (0.0 to 1.0). Essential for Verlet integration stability; prevents infinite oscillation by reducing velocity slightly each frame. |
STRETCH_LIMIT |
5.0 |
Tearing Threshold: A multiplier relative to DISTANCE. If a link is stretched beyond DISTANCE * STRETCH_LIMIT, it is considered broken and removed from the simulation. |
Before compiling, ensure the SFML development library is installed on your system (usually the libsfml-dev package on Debian/Ubuntu-based Linux distributions).
sudo apt-get install libsfml-devTo compile the project, use a C++ compiler setting the standard to C++17. You must link the sfml-graphics, sfml-window, and sfml-system libraries during the build process.
g++ main.cpp -o fabric -lsfml-graphics -lsfml-window -lsfml-system -std=c++17./fabric| Action | Input | Description |
|---|---|---|
| Grab | Left Click + Drag |
Pull and move parts of the cloth. |
| Cut | Right Click + Drag |
Sever connections between points when hovering over them. |