topic Re: Polygon isSelfIntersecting in ArcGIS JavaScript Maps SDK Questions

Polygon isSelfIntersecting

AxelSchaefer — Tue, 17 Dec 2013 13:07:39 GMT

Hi.

I'm working on a redlining function, where I want to check if the polygon is selfIntersecting. I check the geometry, but it says that it's always self-intersecting, even if it isn't.

The code is really simple. Here are the snippets.

        initDraw: function() {             this._tb = new Draw(this.map);              // I DRAW A POLYGON             this._tb.activate(Draw.POLYGON);              this._tb.on("draw-end", lang.hitch(this, this.addToMap));          },          addToMap: function(evt) {             // some stuff              this._tb.deactivate();              var symbol = new SimpleFillSymbol(config.geometryStyles.geofencePolygon);              // MY GEOMETRY == MY POLYGON             var geometry = evt.geometry;              var graphic = new Graphic(geometry, symbol);             this.geofenceGraphicsLayer.add(graphic);              // MY CHECK. Is always alerting, shouldn't do that. :(             if (geometry.isSelfIntersecting) {                 alert("Is Self Intersecting");             } else {                 // do something...             }         },

This is the polygon as JSON that I send to the console. It's a simple triangle.

{"type":"polygon","rings":[[[2343355.197916185,6843378.9380211625],[2343591.077808191,6843221.286650303],[2343284.7325307247,6843149.029771992],[2343355.197916185,6843378.9380211625]]],"_ring":0,"spatialReference":{"wkid":102100},"_centroid":null,"_extent":{"xmin":2343284.7325307247,"ymin":6843149.029771992,"xmax":2343591.077808191,"ymax":6843378.9380211625,"spatialReference":{"wkid":102100}},"_partwise":null}

What's wrong with the check? Why is "isSelfIntersecting" always true, even if I draw some simple polygon?

The geometry seems to be a Polygon. Firebug says:
- declaredClass: "esri.geometry.Polygon"
- type: "polygon"

Does the method not work on a drawn geometry? Am I missing something?

System: JS-API 3.7, Firefox 25.0 with Firebug.

I appreciate any help. Thanks in advance.
Axel

Re: Polygon isSelfIntersecting

JianHuang — Tue, 17 Dec 2013 21:20:08 GMT

Cannot reproduce the issue.
I tried exact same polygon you had:

var polygon = new esri.geometry.Polygon({"type":"polygon","rings":[[[2343355.197916185,6843378.9380211625],[2343591.077808191,6843221.286650303],[2343284.7325307247,6843149.029771992],[2343355.197916185,6843378.9380211625]]],"_ring":0,"spatialReference":{"wkid":102100},"_centroid":null,"_extent":{"xmin":2343284.7325307247,"ymin":6843149.029771992,"xmax":2343591.077808191,"ymax":6843378.9380211625,"spatialReference":{"wkid":102100}},"_partwise":null}); polygon.isSelfIntersecting();//returns false;

I noticed you missed the parentheses at the end of the function isSelfIntersecting(), which means it checks if the function exists or not. If so, it returns the code of the function.

Re: Polygon isSelfIntersecting

AxelSchaefer — Wed, 18 Dec 2013 07:57:54 GMT

I noticed you missed the parentheses at the end of the function isSelfIntersecting(), which means it checks if the function exists or not. If so, it returns the code of the function.

Yeah, that's it.

I missed the parantheses. Doh! I send a comment to js_feedback, because it's also without the parantheses the API-documentation and I simply copy&pasted the code-snippet. 🙂

Thank you very much for your quick and valueable reply.

Axel