ljy-game / vishull2d

Visible regions for 2D poly-lines

vishull2d

Computes the visible region from a point for a given environment represented by a collection of line segments. Based on Amit Patel's blog post

Try out the module yourself in your browser:

http://mikolalysenko.github.com/vishull2d/

Use

Just install it using npm:

npm install vishull2d

Then you can use it in your game like this:

var vishull = require("vishull2d")

//Line segments are encoded as pairs of arrays
var lines = [
  [[10, 10], [10, -10]]
]

//Compute visible hull from the point [0,0]
var region = vishull(lines, [0,0])

require("vishull2d")(segments, center)

Computes the visible hull from the point center

• segments is a collection of line segments
• center is the point from which the visibility is computed

Returns: A counter-clockwise oriented simple polygon representing the visible region.

Note This code assumes that all segments intersect only at their end points. If you have any crossings, you will need to detect them and split them yourself.

Credits

(c) 2013 Mikola Lysenko. MIT License