https://github.com/mikolalysenko/slab-decomposition

Slab decomposition data structure for vertical ray queries
https://github.com/mikolalysenko/slab-decomposition

Last synced: about 2 months ago
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Slab decomposition data structure for vertical ray queries

• Host: GitHub
• URL: https://github.com/mikolalysenko/slab-decomposition
• Owner: mikolalysenko
• License: mit
• Created: 2014-03-01T18:58:34.000Z (almost 11 years ago)
• Default Branch: master
• Last Pushed: 2021-07-15T15:50:06.000Z (over 3 years ago)
• Last Synced: 2024-10-20T14:27:43.385Z (2 months ago)
• Language: JavaScript
• Size: 14.6 KB
• Stars: 5
• Watchers: 3
• Forks: 3
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
slab-decomposition

==================

Given a collection of line segments, constructs a slab decomposition for the purpose of point location queries. This implementation uses a functional red-black tree to store the slabs, requires O(n log(n)) space and answers vertical ray queries in O(log(n)) time.

# Example

```javascript

var makeSlab = require("slab-decomposition")

var slabs = makeSlab([

  [[0, 0], [10, 10]],

  [[10,10], [20, 0]],

  [[5, 5], [20, 0]]

])

for(var i=-10; i<10; ++i) {

  console.log(slabs.castUp([i, -1]))

}

```

# Install

```

npm install slab-decomposition

```

# API

## Constructor

### `var slabs = require("slab-decomposition")(segments)`

Constructs a slab decomposition from the segments

* `segments` is a collection of line segments which only overlap at their end points

**Returns** A slab decomposition data structure

## Methods

### `slabs.castUp(point)`

Casts a vertical ray from `point` going upward along `[0,1]`.  Returns the index of the first segment hit.

* `point` is the base point of the ray

**Returns** The index of the first segment hit by point, otherwise -1 if no segment intersects the ray.

# Credits

(c) 2014 Mikola Lysenko. MIT License