[GIS] How to make a predetermined polygon (circle) from 4 coordinates, the radius and center Longitude and Latitude in OpenLayers

coordinatesgeometryjavascriptopenlayers-2polygon

I know how to make a predetermined polygon in OpenLayers (see below).

Please have a look at http://studio.netnrg.co.za/dev/rnd/blake.loizides/openlayers

var feature2 = new OpenLayers.Feature.Vector(
  OpenLayers.Geometry.fromWKT("POLYGON((-120.828125 -50.3515625, -80.1875 -80.0078125, -40.40625 -20.4140625, -120.828125 -50.3515625))"
  )
);
vectors.addFeatures([feature2]);

I have made an edit circle (40 points in OpenLayers) (my client wanted to see a circle on the map for zones).

The problem I have is that I can only store the following details and not the 40 points or coordinates or vertices to make a circle in OpenLayers. I can only STORE 4 COORDINATES.

In the database I store the bounds top bottom left and right (bottom: -29.054153382197, left: 23.782779686138, right: 23.79286499053, top: -29.044068077805) I will replace the coordinates with the ones in my database.

The radius (525.627982303084)

And the center Longitude and Latitude (lon=23.787822338334,lat=-29.049110730001)

Now I made some calculations below.

My question is how do I now recreate a (circle) with the information I have above that is stored in my database?

I know how to get data from my database and display it on the map, what I don't know is how to make a circle if I can't store the 40 points and only have the radius, the bounds, and the center Lon/Lat to make a circle.

Please if anyone can help me I would be greatly appreciative.

I only want a circle for the look and for no other reason.

My Calculations

Circle from OpenLayers

Best Answer

I'm new to openlayers but this helped me you only need a center point (long lat) and a radius don't forget the function createGeodesicPolygon

Creating vector features onload in OpenLayers

there is a link to a demo

var origin = "new OpenLayers.Geometry.Point(Long Lat)"; 
//then set the radius here 
var polygon = createGeodesicPolygon(origin, RADIUS, 60, 0, map.getProjectionObject())

hope that helps

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