https://github.com/mikolalysenko/split-polygon

Splits a convex polygon by a plane
https://github.com/mikolalysenko/split-polygon

Last synced: about 2 months ago
JSON representation

Splits a convex polygon by a plane

• Host: GitHub
• URL: https://github.com/mikolalysenko/split-polygon
• Owner: mikolalysenko
• License: mit
• Created: 2013-10-10T04:54:12.000Z (about 11 years ago)
• Default Branch: master
• Last Pushed: 2014-06-19T15:20:20.000Z (over 10 years ago)
• Last Synced: 2024-10-20T14:27:40.045Z (2 months ago)
• Language: JavaScript
• Homepage:
• Size: 141 KB
• Stars: 16
• Watchers: 4
• Forks: 4
• Open Issues: 2
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

README

        
split-polygon

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

Splits a *convex* polygon by a plane into two parts (or optionally clips the polygon against a single plane) using the Sutherland-Hodgman algorithm.  Works in arbitrary dimensions, both in the server and the browser

## Install

    npm install split-polygon

## Example

```javascript

var splitPolygon = require("split-polygon")

var poly = [[1,2], [3,4], [0,0]]

var parts = splitPolygon(poly, [0, 1, 3])

console.log(parts.positive)

console.log(parts.negative)

```

## API

```javascript

var splitPolygon = require("split-polygon")

```

### `splitPolygon(poly, plane)`

Splits the *convex* polygon `poly` against plane into two parts, one above the plane and the other below it.  The equation for the plane is determined by:

```javascript

function planeDistance(x) {

  return plane[0] * x[0] + plane[1] * x[1] + ... + plane[n-1] * x[n-1] + plane[n]

}

```

Points above the plane are those where `planeDistance(x) >= 0` and below are those with `planeDistance(x) <= 0`

* `poly` is a *convex* polygon

* `plane` is the plane

**Returns** An object with two properties:

* `positive` is the portion of the polygon above the plane

* `negative` is the portion of the polygon below the plane

### `splitPolygon.positive(poly, plane)`

Same result as splitPolygon, except only returns the positive part.  This saves a bit of memory if you only need one side.

### `splitPolygon.negative(poly, plane)`

Ditto, except returns only the negative part.

## Credits

(c) 2013 Mikola Lysenko. MIT License