point-in-svg-polygon

Determine if an point is inside a polygon

Works with arbitrary polygons (as in: curves!) and is usable in Node.JS as well as in your browser (through Browserify).

What it does

Given an SVG path and a point, it'll tell you whether the point lies within the SVG path.

For instance:

Color	Inside red shape (convex)?	Inside blue shape (concave)?
Red	No	No
Green	Yes	Yes
Blue	Yes	No
Orange	No	Yes

Usage

Give it a point and a path string:

var pointInSvgPolygon = require("point-in-svg-polygon");

// See the path specification for the correct format
// https://developer.mozilla.org/en/docs/Web/SVG/Tutorial/Paths
var pathString = "M1,1 C1,1 501,1 501,501 C501,1001 1,1001 1,1001 L1,1 Z";
var result = pointInSvgPolygon.isInside([x, y], pathString);

You can amortize the path splitting by performing it once:

var pointInSvgPolygon = require("point-in-svg-polygon");

// See the path specification for the correct format
// https://developer.mozilla.org/en/docs/Web/SVG/Tutorial/Paths
var pathString = "M1,1 C1,1 501,1 501,501 C501,1001 1,1001 1,1001 L1,1 Z";
var segments = pointInSvgPolygon.segments(pathString);

// Use it multiple times:
var result = pointInSvgPolygon.isInside([x, y], segments);

This is useful if you have to test a lot of points.

Credits

Originally based on the work by Kevin Lindsey. Severly trimmed down: 6.3Kb footprint when minified, drops down to 2.9Kb when gzipped.

License

Copyright (c) 2016, Ruben Vermeersch
Copyright (c) 2013, Kevin Lindsey
All rights reserved.

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

  Redistributions of source code must retain the above copyright notice, this
  list of conditions and the following disclaimer.

  Redistributions in binary form must reproduce the above copyright notice, this
  list of conditions and the following disclaimer in the documentation and/or
  other materials provided with the distribution.

  Neither the name of the {organization} nor the names of its
  contributors may be used to endorse or promote products derived from
  this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.