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Use Schaub's topology-preserving simplification method for Polygons and MultiPolygons

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This commit is contained in:
Tom Payne
2013-12-13 13:52:38 +01:00
parent 5b1bbe15dd
commit 594cee01e4
3 changed files with 13 additions and 12 deletions
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8
src/ol/geom/multipolygon.js
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@@ -143,10 +143,10 @@ ol.geom.MultiPolygon.prototype.getSimplifiedGeometryInternal =
function(squaredTolerance) { function(squaredTolerance) {
var simplifiedFlatCoordinates = []; var simplifiedFlatCoordinates = [];
var simplifiedEndss = []; var simplifiedEndss = [];
simplifiedFlatCoordinates.length = simplifiedFlatCoordinates.length = ol.geom.simplify.schaubss(
ol.geom.simplify.douglasPeuckerss(this.flatCoordinates, 0, this.flatCoordinates, 0, this.endss_, this.stride,
this.endss_, this.stride, squaredTolerance, simplifiedFlatCoordinates, Math.sqrt(squaredTolerance),
0, simplifiedEndss); simplifiedFlatCoordinates, 0, simplifiedEndss);
var simplifiedMultiPolygon = new ol.geom.MultiPolygon(null); var simplifiedMultiPolygon = new ol.geom.MultiPolygon(null);
simplifiedMultiPolygon.setFlatCoordinates( simplifiedMultiPolygon.setFlatCoordinates(
ol.geom.GeometryLayout.XY, simplifiedFlatCoordinates, simplifiedEndss); ol.geom.GeometryLayout.XY, simplifiedFlatCoordinates, simplifiedEndss);

5
src/ol/geom/polygon.js
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@@ -157,8 +157,9 @@ ol.geom.Polygon.prototype.getSimplifiedGeometryInternal =
function(squaredTolerance) { function(squaredTolerance) {
var simplifiedFlatCoordinates = []; var simplifiedFlatCoordinates = [];
var simplifiedEnds = []; var simplifiedEnds = [];
simplifiedFlatCoordinates.length = ol.geom.simplify.douglasPeuckers( simplifiedFlatCoordinates.length = ol.geom.simplify.schaubs(
this.flatCoordinates, 0, this.ends_, this.stride, squaredTolerance, this.flatCoordinates, 0, this.ends_, this.stride,
Math.sqrt(squaredTolerance),
simplifiedFlatCoordinates, 0, simplifiedEnds); simplifiedFlatCoordinates, 0, simplifiedEnds);
var simplifiedPolygon = new ol.geom.Polygon(null); var simplifiedPolygon = new ol.geom.Polygon(null);
simplifiedPolygon.setFlatCoordinates( simplifiedPolygon.setFlatCoordinates(

12
test/spec/ol/geom/polygon.test.js
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@@ -321,17 +321,17 @@ describe('ol.geom.Polygon', function() {
describe('#getSimplifiedGeometry', function() { describe('#getSimplifiedGeometry', function() {
it('returns the expected result', function() { it('returns the expected result', function() {
var simplifiedGeometry = polygon.getSimplifiedGeometry(1); var simplifiedGeometry = polygon.getSimplifiedGeometry(9);
expect(simplifiedGeometry).to.be.an(ol.geom.Polygon); expect(simplifiedGeometry).to.be.an(ol.geom.Polygon);
expect(simplifiedGeometry.getCoordinates()).to.eql( expect(simplifiedGeometry.getCoordinates()).to.eql(
[[[3, 0], [0, 6], [6, 6], [4, 3]]]); [[[3, 0], [0, 3], [0, 6], [6, 6], [3, 3]]]);
}); });
it('caches multiple simplified geometries', function() { it('caches multiple simplified geometries', function() {
var simplifiedGeometry1 = polygon.getSimplifiedGeometry(1); var simplifiedGeometry1 = polygon.getSimplifiedGeometry(4);
var simplifiedGeometry2 = polygon.getSimplifiedGeometry(2); var simplifiedGeometry2 = polygon.getSimplifiedGeometry(9);
var simplifiedGeometry3 = polygon.getSimplifiedGeometry(1); var simplifiedGeometry3 = polygon.getSimplifiedGeometry(4);
var simplifiedGeometry4 = polygon.getSimplifiedGeometry(2); var simplifiedGeometry4 = polygon.getSimplifiedGeometry(9);
expect(simplifiedGeometry1).to.be(simplifiedGeometry3); expect(simplifiedGeometry1).to.be(simplifiedGeometry3);
expect(simplifiedGeometry2).to.be(simplifiedGeometry4); expect(simplifiedGeometry2).to.be(simplifiedGeometry4);
}); });