https://github.com/mikolalysenko/simplify-planar-graph

Simplifies a 2D polygonal region
https://github.com/mikolalysenko/simplify-planar-graph

Last synced: about 2 months ago
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Simplifies a 2D polygonal region

• Host: GitHub
• URL: https://github.com/mikolalysenko/simplify-planar-graph
• Owner: mikolalysenko
• License: mit
• Created: 2014-04-10T22:03:32.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2014-05-07T21:10:58.000Z (over 10 years ago)
• Last Synced: 2024-10-21T15:37:53.931Z (2 months ago)
• Language: JavaScript
• Size: 184 KB
• Stars: 4
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
simplify-planar-graph

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

Simplifies a planar graph by removing small or nearly flat corners.

# Example

```javascript

var simplify = require("simplify-planar-graph")

//Create a circle

var positions = []

var edges = []

for(var i=0; i<100; ++i) {

  var theta = i / 100 * Math.PI * 2.0

  positions.push([Math.cos(theta), Math.sin(theta)])

  edges.push([i, (i+1)%100])

}

//Simplify it

console.log(simplify(edges, positions, 0.1))

```

Output:

```javascript

{ positions:

   [ [ 0.9921147013144779, 0.12533323356430426 ],

     [ 0.8090169943749475, 0.5877852522924731 ],

     [ 0.48175367410171516, 0.8763066800438637 ],

     [ -0.30901699437494734, 0.9510565162951536 ],

     [ -0.7705132427757891, 0.6374239897486899 ],

     [ -0.9980267284282716, 0.06279051952931358 ],

     [ -0.9510565162951535, -0.30901699437494773 ],

     [ -0.5877852522924732, -0.8090169943749473 ],

     [ -0.18738131458572463, -0.9822872507286887 ],

     [ 0.535826794978996, -0.8443279255020155 ],

     [ 0.7705132427757894, -0.6374239897486896 ] ],

  edges:

   [ [ 0, 1 ],

     [ 1, 2 ],

     [ 2, 3 ],

     [ 3, 4 ],

     [ 4, 5 ],

     [ 10, 0 ],

     [ 5, 6 ],

     [ 6, 7 ],

     [ 7, 8 ],

     [ 8, 9 ],

     [ 9, 10 ] ] }

```

# Install

```

npm install simplify-planar-graph

```

# API

#### `require("simplify-planar-graph")(edges, positions, tolerance)`

Simplies a planar graph to a given tolerance

* `edges` are the edges of the graph represented by pairs of vertex indices

* `positions` is a list of vertex coordinates encoded as an array of 2D arrays

* `tolerance` controls the target aspect ratio of the corners of the mesh

**Returns** A new planar graph encoded as a JSON object with two properties:

* `edges` is an array of edges encoded as pairs of indices

* `positions` is an array of positions for the simplicial complex

**Note** The current implementation does not detect the removal of features which cross existing line segments.  Picking a high tolerance value may result in destroying the planarity of the resulting graph.  Eventually if it becomes a priority I may go back and implement code to detect and handle these cases.

# Credits

(c) 2014 Mikola Lysenko. MIT License