https://github.com/ralith/planetmap

Streaming planetary terrain mapping
https://github.com/ralith/planetmap

Last synced: 12 months ago
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Streaming planetary terrain mapping

• Host: GitHub
• URL: https://github.com/ralith/planetmap
• Owner: Ralith
• Created: 2019-02-24T23:23:57.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2025-01-10T13:15:00.000Z (over 1 year ago)
• Last Synced: 2025-04-10T05:04:34.844Z (over 1 year ago)
• Language: Rust
• Size: 231 KB
• Stars: 59
• Watchers: 4
• Forks: 6
• Open Issues: 5
• Metadata Files:
  • Readme: README.md

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README

          
# Planetmap

Planetmap is a library for processing lazily evaluated radial

functions with dynamic level-of-detail.

## Screenshots

![high orbit](https://user-images.githubusercontent.com/3484507/65808207-c6e2ce80-e18a-11e9-9625-6ad85e5d54d5.png)

![low orbit](https://user-images.githubusercontent.com/3484507/65808209-c77b6500-e18a-11e9-84d3-9efa44f2f902.png)

![close](https://user-images.githubusercontent.com/3484507/65808208-c6e2ce80-e18a-11e9-83e1-100f0863473d.png)

## Terrain Rendering

Planetmap is motivated by the desire to model to-scale planetary

terrain in real time on commodity hardware. To accomplish this, it

addresses multiple challenges:

- Dynamic level of detail

- Streaming larger-than-memory or procedural heightmap data

- Addressing the surface of the sphere without singularities

- Maintaining numerical stability over massive distances

This is accomplished by organizing data into a 6 virtual quadtrees,

each corresponding to one face of a cubemap. Each node in a quadtree,

referred to as a `Chunk`, can be associated with a square grid of

height samples, each of which represents the altitude relative to sea

level along a ray originating at the center of a planet. Streaming and

level of detail can then be implemented with a `CacheManager`

associated with GPU-resident buffers.

When generating geometry to be displaced by the heightmap, care must

be taken to ensure numerical stability and avoid hairline cracks

between neighboring chunks. One effective tactic is to upload the

corners of each chunk from the CPU, then find interior points using

interpolation in a vertex shader.

## Features

- `parry` exposes helpers for rapier-compatible collision

  detection against the surface of a radial heightmap

- `simd` exposes `simdeez`-based iterators for data-parallel

  computation of sample coordinates within a `Chunk` or

  `chunk::Coord`, useful for fast noise sampling