Pylanet

Pylanet is a procedural planet generator written in Python. It builds a UV sphere, deforms it with layered 3D Perlin noise, assigns biome colors, and exports the result as a vertex-colored PLY mesh. It also includes a local Web UI for generating and inspecting planets interactively.

Features

• Procedural 3D planet meshes
• Configurable resolution, seed, terrain relief, sea level, octaves, gain, continent scale, plains bias, biome bias, and color texture
• Planet presets: earthlike, arid, frozen, oceanic, and volcanic
• Layered biome coloring for oceans, beaches, grasslands, forests, rainforests, savannas, deserts, tundra, rock, snow, basalt, and lava
• CLI export to planet.ply
• WebGL viewer with rotate and zoom controls
• Web UI PLY saving after generation
• Black universe-style background
• No web framework required; the UI runs on Python's built-in HTTP server

Setup

python -m venv venv

**Windows:**
```powershell
.\venv\Scripts\Activate.ps1

**Linux/macOS:**
```bash
source venv/bin/activate

```powershell
pip install -r requirements.txt

Export A PLY

Edit config.yaml, then run:

python main.py

The mesh is written to the path configured in:

export:
  filename: planet.ply

Open the exported PLY in tools such as Blender, MeshLab, or CloudCompare. The file includes RGB vertex colors.

Run The Web UI

python web.py

Open:

http://127.0.0.1:8000

Use Generate to rebuild the planet after changing settings. Drag on the planet to rotate it and use the mouse wheel or trackpad scroll to zoom. Use Save PLY to download the current generated mesh with vertex colors.

The Web UI exposes resolution as one slider. The slider controls latitude segments, and longitude is set automatically to a 4:3 ratio for cleaner spherical coverage.

Configuration

The main controls live in config.yaml.

planet:
  preset: earthlike
  base_radius: 1.0
  resolution:
    lat: 180
    lon: 240

noise:
  seed: 106
  amplitude: 0.28
  octaves: 6
  lacunarity: 2.0
  gain: 0.5

terrain:
  pattern_scale: 1.0
  color_detail: 0.5
  plains_bias: 0.0
  continent_scale: 0.95
  mountain_strength: 0.34
  detail_strength: 0.08
  moisture: 0.62
  temperature: 0.58
  ice_caps: 0.35
  biome_biases:
    ocean: 1.0
    desert: 1.0
    grassland: 1.0
    forest: 1.0
    snow: 1.0

Useful knobs:

• seed: changes the generated world while keeping the same settings
• amplitude: increases or reduces terrain height
• sea_level: controls how much land is underwater
• pattern_scale: changes the overall size of noise patterns across terrain and biomes
• color_detail: controls how strongly biome colors are broken up by layered surface texture
• plains_bias: flattens ridges and compresses elevation to make broader plain areas
• biome_biases: controls how strongly each biome competes during classification; 1.0 is neutral
• continent_scale: lower values create larger landmasses; higher values create smaller, noisier ones
• mountain_strength: adds sharper ridged terrain
• detail_strength: adds fine surface variation
• moisture, temperature, ice_caps: influence biome placement
• lat, lon: control mesh resolution

Project Layout

Pylanet/
  config.py            YAML loader
  config.yaml          default planet settings
  main.py              CLI PLY exporter
  planetgen.py         shared planet generation pipeline
  web.py               local Web UI server
  export/ply.py        PLY writer
  mesh/sphere.py       UV sphere mesh builder
  procnoise/perlin.py  3D Perlin/fBM noise
  procnoise/deform.py  terrain deformation and biome classification
  static/              WebGL viewer

Notes

High resolutions create larger responses in the Web UI and larger PLY files. The default lat: 180 and lon: 240 gives much sharper biome boundaries; lower it while exploring if generation feels slow.