Developer Discussions

[Jacques]

Hi Guys,

Is there a way in Portal SDK to get the distance between 2 given points.

There reason I am asking is , I need to create a polygon from the result of the $GP.map.draw.circle function , need to pass the polygon array to a function.

$GP.map.draw.circle , look like it returns the center point and 1 side point to form the radius , so I want to calculate the border points that will form the circle polygon but i need the length of the radius.

Kind Regards

Jacques

[jan.neumann]

Hi Jacques,

I am afraid that there's no simple solution or answer to this. I am rather curious, what is the desired aim or workflow? Why is the circle drawn? What actually does the user want?

Thanks,

Jan

[Jacques]

Hi Jan,

I will then go the math route.

The reason is that the wms can handle bbox and polygons.

Most pivot field are round , so I dont want the client to place a load of polygon points to form a circle.

I would like him to draw the circle , then I will generate the polygon and pass it to the service.

So , the circle function gives the center point and bounding point , so one can calculate the radius and from there the points making the circle.

Well , that is the idea then.

Kind Regards

Jacques

[jan.neumann]

I see. But even so, you will send a rectangle anyway and the user will see rectangular-results. It sounds simpler to convince the customer to draw a rectangle around the pivot field. It's just my thought, but drawing a rectangle around a circle is more or less same of difficulty as hitting the center of a circle. But that's just my thought.

[Jacques]

Hi Jan,

I will use the center point and the radius to plot a point every 10 degrees for 360 degrees

The thing is , I cant use a bounding box or triangle to be drawn around the pivot , both will result in unwanted vegitation making the quantified data inacurate.

Will let you know if I succeed or crash and burn.

Kind Regards

Jacques

[Jacques]

Hi Jan,

So basically this is what I have done.

(See image)

I used $GP.map.draw.circle to draw the circle.

Then I took the center x,y and the wall x,y and calculated the radius.

Then I used the center x,y radius to radian and ploted the 36 points making up the circumference of the circle.(closed polygon)

I will then send his the service and hope it works

Regards

Jacques

Capture.JPG ‏34 KB

[jan.neumann]

Nice, good old math

[hbm]

It wasn't entirely clear to me from the beginning what you were trying to achieve, Jacques. But now I understand it and it looks like a nice solution. Awesome!

[Jacques · Accepted solution]

Hi Guys,

So if someone would need this some day , or would like to improve on this (just a quick solution) nothing to fancy...please feel free (needs some error handling still...etc)

/===DRAW CIRCLE FUNCTION==
$GP.map.draw.circle({}, function(retCircle) {
    var Circlegeojson = retCircle.feature.get_geoJSON();

    //==Center X==
    var CircleCenterX = JSON.stringify([Circlegeojson.geometry.coordinates[0][0][0]]);
    CircleCenterX = CircleCenterX.replace(/[\[\]']/g, '');

    //==Center Y==
    var CircleCenterY = JSON.stringify([Circlegeojson.geometry.coordinates[0][0][1]]);
    CircleCenterY = CircleCenterY.replace(/[\[\]']/g, '');

    //==Radius X==
    var CircleRadiusX = JSON.stringify([Circlegeojson.geometry.coordinates[0][1][0]]);
    CircleRadiusX = CircleRadiusX.replace(/[\[\]']/g, '');

    //==Radius Y==
    var CircleRadiusY = JSON.stringify([Circlegeojson.geometry.coordinates[0][1][1]]);
    CircleRadiusY = CircleRadiusY.replace(/[\[\]']/g, '');

    var FinX = CircleCenterX - CircleRadiusX;
    var FinY = CircleCenterY - CircleRadiusY;

    //==LEN OF RADIUS==
    var Rlen = Math.sqrt(Math.pow(CircleCenterX - CircleRadiusX, 2) + Math.pow(CircleCenterY - CircleRadiusY, 2));

    var points = 20;
    var slice = parseFloat(2 * Math.PI / points);
    var angle = 0;
    var CrclPoly;
    var FrstX;
    var FrstY;

    for (i = 0; i < points; i++) {
        angle = slice * i;

        var newX = (parseFloat(CircleCenterX) + parseFloat(Rlen) * parseFloat(Math.cos(angle)));
        var newY = (parseFloat(CircleCenterY) + parseFloat(Rlen) * parseFloat(Math.sin(angle)));

        if (i + 1 != points) {
            if (!CrclPoly) {
                FrstX = newX;
                FrstY = newY;
                CrclPoly = newX + ' ' + newY + ",";
            } else {
                CrclPoly = CrclPoly + newX + ' ' + newY + ",";
            }
        } else {
            CrclPoly = CrclPoly + newX + ' ' + newY + "," + FrstX + ' ' + FrstY;
        }
        $GP.crs.setCurrent("EPSG:3857", function() {
            $GP.map.draw.point({
                x: newX,
                y: newY
            });
        });
    }
    //==SHOW WINDOW==
    showChartWindow();
    //==CALL FUNCTION===
    getNDVI_ND_ByPolygon(ChrtDateFrom, ChrtDateTo, CrclPoly);
});