Rope Simulation

This project performs physics-based rope simulation using Verlet integration. Users can interactively move the rope, adjust gravity, and damping settings.

Features

• Verlet Integration: Uses Verlet integration for realistic physics simulation.
• Interactive Usage: Drag and drop rope segments with the mouse.
• Real-time Adjustments: Adjust gravity, damping, segment count, and segment length in real-time.
• Camera System: Zoom in/out and pan (camera movement) features.
• Interactive Interface: Easy control with sliders and buttons.

Technologies Used

Technology	Version	Description
Python	3.14	Main programming language
Pygame	2.6.1	2D graphics, game loop, and user interface

Project Structure

rope_sim/
├── src/
│   ├── main.py          # Main entry point and game loop
│   ├── requirements.txt # Dependencies (pygame==2.6.1)
│   ├── rope.py          # Rope class (Verlet integration)
│   ├── physics/
│   │   ├── __init__.py
│   │   ├── particle.py  # Particle (mass) class
│   │   └── constraint.py # Constraint (distance constraint) class
│   └── gui/
│       ├── __init__.py
│       └── gui.py       # User interface classes
└── venv/                # Python virtual environment

Installation

1. Clone the repository

git clone <repourl>
cd rope_sim

2. Create and activate virtual environment

python -m venv venv
source venv/bin/activate  # macOS/Linux
# or
venv\Scripts\activate     # Windows

3. Install dependencies

cd src
pip install -r requirements.txt

Running

cd src
python main.py

Keyboard Controls

Key	Function
SPACE	Start/Stop simulation
R	Reset rope
ESC	Exit
+ / Kp+	Zoom in
-	Zoom out
Drag	Move rope segments

UI Controls

• Reset Rope: Reset rope to initial position
• Gravity Slider: Gravity force (0.1 - 2.5)
• Damping Slider: Damping coefficient (0.85 - 1.0)
• Segments Slider: Number of segments (2 - 5000)
• Segment Length Slider: Length of each segment (15 - 187)
• Zoom +/-/Reset: Camera zoom controls

Technical Details

Verlet Integration

The project uses Verlet integration for physics simulation:

v = (current_pos - old_pos) * damping
new_pos = current_pos + v + gravity * dt²

This method provides numerical stability and helps rope-like flexible structures appear realistic.

System Components

1. Particle

   • Represents a mass
   • Stores position, velocity, and mass information
   • is_fixed: Is this a fixed point?
   • is_being_dragged: Is the user dragging it?

2. Constraint

   • Maintains distance between two particles
   • Controls flexibility with stiffness parameter
   • Iterative solving for stability

3. Rope

   • Combines particles and constraints
   • update(): Physics update
   • draw(): Screen drawing
   • drag_particle(): Mouse interaction

4. Camera

   • Zoom and pan operations
   • World coordinates ↔ Screen coordinates transformation

Screenshots

The simulation screen includes:

• Background: Grid system
• Rope: White particles and gray segments
• UI Panel: Parameter controls in the top-right corner
• Info Panel: Real-time simulation statistics

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Note: This is an educational physics simulation project written with the Pygame library.

Vibe Coding Note: This project was developed in approximately 2 hours of vibe coding.