isabella232 / lineclip

A very fast JavaScript polyline and polygon clipping library

lineclip

A very fast JavaScript library for clipping polylines and polygons by a bounding box.

• uses Cohen-Sutherland algorithm for line clipping
• uses Sutherland-Hodgman algorithm for polygon clipping

lineclip(
    [[-10, 10], [10, 10], [10, -10]], // line
    [0, 0, 20, 20]); // bbox
// returns [[[0, 10], [10, 10], [10, 0]]]

API

lineclip.polyline(points, bbox[, result])

• points — an array of [x, y] points
• bbox — a bounding box as [xmin, ymin, xmax, ymax]
• result — an array to append the results to

Returns an array of clipped lines.

lineclip is an alias to lineclip.polyline.

lineclip.polygon(points, bbox)

Returns a clipped polygon.

Install

Install with NPM:

npm install lineclip

To build a browser-compatible version, clone the repository locally, then run:

npm install -g browserify
browserify -s lineclip index.js > lineclip.js

Changelog

1.1.5 (Sep 23, 2015)

• Fixed a bug where polygon clip broke on out-of-bbox polygons.

1.1.4 (Sep 22, 2015)

• Fixed a bug where last point was omitted if the last two points are in bbox.
• Fixed a bug where a line outside of bbox would produce [[]] instead of [].

1.1.3 (Sep 12, 2015)

• Fixed a polygon clipping race condition.

1.1.2 (Sep 11, 2015)

• Fixed a bug that completely broke the clipping on many cases. Sorry!

1.1.1 (Sep 11, 2015)

• Fixed a polyline clipping edge case.

1.1.0 (Sep 11, 2015)

• Added Sutherland-Hodgeman polygon clipping (lineclip.polygon).

1.0.1 (Sep 11, 2015)

• Minor code cleanup and optimizations.

1.0.0 (Sep 8, 2015)

• Initial release.