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Point-in-polygon improvements

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As suggested by @tschaub in #674, geom.pointInPoly is not needed
if we have geom.LinearRing#containsCoordinate. This pull request
also adds tests and documentation on the limitations of the
containsCoordinate method.

I think for now it is ok to keep geometry/topology functions as
simple as possible in ol3. If we decide to not rely on third
party libraries like jsts for topology operations, we can always
refine what we have and e.g. port topology operations over from
ol2.
This commit is contained in:
ahocevar
2013-05-07 10:49:51 +02:00
parent aa3cc0cec4
commit 666a010e3b
5 changed files with 109 additions and 39 deletions
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22
src/ol/geom/polygon.js
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@@ -91,22 +91,24 @@ ol.geom.Polygon.prototype.getType = function() {
/**
* Check whether a given coordinate is inside this polygon.
* Check whether a given coordinate is inside this polygon. Note that this is a
* fast and simple check - points on an edge or vertex of the polygon or one of
* its inner rings are either classified inside or outside.
*
* @param {ol.Coordinate} coordinate Coordinate.
* @return {boolean} Whether the coordinate is inside the polygon.
*/
ol.geom.Polygon.prototype.containsCoordinate = function(coordinate) {
var rings = this.rings;
var containsCoordinate = ol.geom.pointInPolygon(coordinate,
rings[0].getCoordinates());
if (containsCoordinate) {
// if inner ring contains point, polygon does not contain it
for (var i = 1, ii = rings.length; i < ii; ++i) {
if (ol.geom.pointInPolygon(coordinate, rings[i].getCoordinates())) {
containsCoordinate = false;
break;
}
var containsCoordinate;
for (var i = 0, ii = rings.length; i < ii; ++i) {
containsCoordinate = rings[i].containsCoordinate(coordinate);
// if inner ring (i > 0) contains coordinate, polygon does not contain it
if (i > 0) {
containsCoordinate = !containsCoordinate;
}
if (!containsCoordinate) {
break;
}
}
return containsCoordinate;