# Trajectory Plotting

This Python script can read and visualize the binary trajectory files generated by the orbital simulator.

## Installation

First, install the required Python dependencies:

```bash
pip install -r requirements.txt
```

## Usage

### Basic Usage

```bash
# Plot trajectories from a simulation output file
python plot_trajectories.py trajectory_output.bin
```

### Options

- `--2d-only`: Only show 2D plot (X-Y plane)  
- `--3d-only`: Only show 3D plot
- `--energy`: Also show energy conservation plot
- `--animate`: Show animated trajectories with real-time simulation
- `--save-animation <filename>`: Save animation as MP4 file (requires ffmpeg)
- `--static`: Show static plots (default behavior)
- `--interval <ms>`: Animation frame interval in milliseconds (default: auto-scaled)
- `--target-duration <seconds>`: Target animation duration (default: 60)
- `--center <body_name>`: Center animation/plot on specified body (e.g., "Sun", "Earth")
- `--list-bodies`: List available bodies in trajectory file and exit

### Examples

```bash
# Run a simulation and plot the results
cargo run --bin simulator -- --config config/planets.json --time 365d --step-size 3600 --output-file solar_system.bin
python plot_trajectories.py solar_system.bin

# List available bodies in trajectory file
python plot_trajectories.py solar_system.bin --list-bodies

# Show animated trajectories centered on the Sun
python plot_trajectories.py solar_system.bin --animate --center Sun

# Show Earth-centered view (great for seeing Moon's orbit)
python plot_trajectories.py solar_system.bin --animate --center Earth --2d-only

# Show only 2D animation with custom speed
python plot_trajectories.py solar_system.bin --animate --2d-only --interval 100

# Save animation as MP4 file (Sun-centered)
python plot_trajectories.py solar_system.bin --animate --center Sun --save-animation solar_system_animation

# Show 3D trajectories with energy plot (static, Earth-centered)
python plot_trajectories.py solar_system.bin --3d-only --energy --static --center Earth
```

## Output

The script can display:

### Static Plots
- **2D Plot**: Trajectories in the X-Y plane with starting positions (circles) and ending positions (squares)
- **3D Plot**: Full 3D orbital trajectories  
- **Energy Plot** (optional): Shows kinetic and total energy over time to verify energy conservation

### Animated Plots
- **2D Animation**: Real-time orbital motion in the X-Y plane with time display
- **3D Animation**: Full 3D animated orbital trajectories
- **Time Display**: Shows current simulation time in seconds/hours/days
- **Trails**: Recent positions shown as fading trails behind each body
- **MP4 Export**: Save animations as video files (requires ffmpeg)

Each celestial body is plotted in a different color with its name in the legend.

## File Format

The binary trajectory file contains serialized snapshots with:
- Timestamp (f64)
- Array of bodies, each containing:
  - Name (String)
  - Mass (f64) 
  - Position (3x f64)
  - Velocity (3x f64)
  - Acceleration (3x f64)