ashatora/openlayers
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Add functions to create regular polygons

Browse Source
This commit is contained in:
Andreas Hocevar
2015-05-08 11:20:26 +02:00
parent 250221cded
commit 901a0f6d8e
2 changed files with 84 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

50
src/ol/geom/polygon.js
View File

@@ -2,6 +2,7 @@ goog.provide('ol.geom.Polygon');
goog.require('goog.array');
goog.require('goog.asserts');
goog.require('goog.math');
goog.require('ol.extent');
goog.require('ol.geom.GeometryLayout');
goog.require('ol.geom.GeometryType');
@@ -422,3 +423,52 @@ ol.geom.Polygon.fromExtent = function(extent) {
ol.geom.GeometryLayout.XY, flatCoordinates, [flatCoordinates.length]);
return polygon;
};
/**
* Create a regular polygon from a circle.
* @param {ol.geom.Circle} circle Circle geometry.
* @param {number=} opt_sides Number of sides of the polygon. Default is 32.
* @param {number=} opt_angle Start angle for the first vertex of the polygon in
* radians. Default is 0.
* @return {ol.geom.Polygon} Polygon geometry.
*/
ol.geom.Polygon.fromCircle = function(circle, opt_sides, opt_angle) {
var sides = goog.isDef(opt_sides) ? opt_sides : 32;
var stride = circle.getStride();
var layout = circle.getLayout();
var polygon = new ol.geom.Polygon(null, layout);
var flatCoordinates = goog.array.repeat(0, stride * (sides + 1));
var ends = [flatCoordinates.length];
polygon.setFlatCoordinates(layout, flatCoordinates, ends);
ol.geom.Polygon.makeRegular(
polygon, circle.getCenter(), circle.getRadius(), opt_angle);
return polygon;
};
/**
* Modify the coordinates of a polygon to make it a regular polygon.
* @param {ol.geom.Polygon} polygon Polygon geometry.
* @param {ol.Coordinate} center Center of the regular polygon.
* @param {number} radius Radius of the regular polygon.
* @param {number=} opt_angle Start angle for the first vertex of the polygon in
* radians. Default is 0.
*/
ol.geom.Polygon.makeRegular = function(polygon, center, radius, opt_angle) {
var flatCoordinates = polygon.getFlatCoordinates();
var layout = polygon.getLayout();
var stride = polygon.getStride();
var ends = polygon.getEnds();
goog.asserts.assert(ends.length === 1, 'only 1 ring is supported');
var sides = flatCoordinates.length / stride - 1;
var startAngle = goog.isDef(opt_angle) ? opt_angle : 0;
var angle, coord, offset;
for (var i = 0; i <= sides; ++i) {
offset = i * stride;
angle = startAngle + (goog.math.modulo(i, sides) * 2 * Math.PI / sides);
flatCoordinates[offset] = center[0] + (radius * Math.cos(angle));
flatCoordinates[offset + 1] = center[1] + (radius * Math.sin(angle));
}
polygon.setFlatCoordinates(layout, flatCoordinates, ends);
};