# Orbital Simulator

A fast N-body orbital mechanics simulator written in Rust.  
Simulate the motion of celestial bodies under Newtonian gravity, with easy configuration and efficient output for visualization.

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## Features

- **N-body simulation**
- **Configurable initial conditions** via JSON
- **Binary trajectory files**
- **Progress bar** 
- **Unit normalization** 
- **Ready for visualization** (Coming Soon)

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## Getting Started

### Prerequisites

- [Rust](https://www.rust-lang.org/tools/install) (edition 2021 or later)
- Python (optional, for animation/visualization)

### Build

```bash
cargo build --release
```

### Run

```bash
cargo run --release -- \
  --config path/to/your_config.json \
  --time 30d \
  --step-size 10.0 \
  --output-file trajectory.bin
```

**Arguments:**

- `--config` (required): Path to your JSON config file with initial body states.
- `--time` (required): Total simulation time (e.g. `10s`, `5m`, `2h`, `100d`).
- `--step-size`: Simulation step size in seconds (default: `10.0`).
- `--output-file` (required): Where to save the trajectory data.
- `--steps-per-save`: How often to update the progress bar and save (default: `1000`).

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## Configuration

The config file is a JSON file describing the initial state of each body.  
Examples provided in config/

```json
{
  "bodies": [
    {
      "name": "BodyName",
      "mass": 1e10, //kg
      "position": [0.0, 0.0, 0.0], //meters
      "velocity": [0.0, 0.0, 0.0] // m/s
    },
    ...
  ]
}
```

- **Units:**  
  - Mass: kilograms (kg)  
  - Position: meters (m)  
  - Velocity: meters per second (m/s)

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## Output

- The simulator writes binary snapshots of the system state to the output file using [bincode](https://docs.rs/bincode/).
- Each snapshot contains the simulation time and the real (de-normalized) positions, velocities, and masses of all bodies.

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## Animation

Coming soon.

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## Extending

- Add more bodies or change initial conditions in the config file.
- Adjust step size and simulation time for accuracy/performance trade-offs.
- The code is modular and ready for extension (e.g., new force laws, output formats, or integrators).

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## License

MIT License

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## Acknowledgments

- [Rust](https://www.rust-lang.org/)
- [glam](https://crates.io/crates/glam) for fast vector math
- [clap](https://crates.io/crates/clap) for CLI parsing
- [indicatif](https://crates.io/crates/indicatif) for progress bars
- [serde](https://crates.io/crates/serde) and [bincode](https://crates.io/crates/bincode) for serialization

---

## Author

- Thomas Faour