Example FsLatLonPolygon

[Nach]

How can I give coordinates to FsLatLonPolygon so I can later check if the plane is inside the polygon?

[Paul Henty]

The constructor takes in an array of FsLatLonPoint that define the points (vertices) of a closed polygon. There can be any number of points. The polygon can be convex, concave or complex (having self-intersecting sides). 

Here is an example I used to test the class. I just supply hard-coded points of the outline of London: (I've removed lots of points in the middle for this example):

FsLatLonPoint[] points = new FsLatLonPoint[]
{
   new FsLatLonPoint(51.828207,-2.669643),
   new FsLatLonPoint(51.823186,-2.654353),
   new FsLatLonPoint(51.827549,-2.646808),
   new FsLatLonPoint(51.836629,-2.638694),
   // Points removed
   new FsLatLonPoint(51.796211,-2.663467),
   new FsLatLonPoint(51.801533,-2.68468),
   new FsLatLonPoint(51.812531,-2.68296),
   new FsLatLonPoint(51.828207,-2.669643)
};
FsLatLonPolygon myPolygon = new FsLatLonPolygon(points);

Normally you would get the points from a database or mapping service, so you would need to read the points and create the array of FsLatLonPoint[] in code.

If you need more specific help, let me know how you're getting the polygon point data and what format the data is in. I can then explain how to convert them to the point array.

Paul

[Nach]

For VB.NET?

[Paul Henty]

        Dim points As FsLatLonPoint() =
        {
            New FsLatLonPoint(51.828207, -2.669643),
            New FsLatLonPoint(51.823186, -2.654353),
            New FsLatLonPoint(51.827549, -2.646808),
            New FsLatLonPoint(51.836629, -2.638694),
            New FsLatLonPoint(51.796211, -2.663467),
            New FsLatLonPoint(51.801533, -2.68468),
            New FsLatLonPoint(51.812531, -2.68296),
            New FsLatLonPoint(51.828207, -2.669643)
        }
        Dim myPolygon As FsLatLonPolygon = New FsLatLonPolygon(points)

Paul

[Nach]

        FsLatLonPoint[] sector1pol = new FsLatLonPoint[]
        {
            new FsLatLonPoint(39.158189, -6.560815),
            new FsLatLonPoint(39.44173, -6.291623),
            new FsLatLonPoint(39.847553, -4.565154),
            new FsLatLonPoint(39.594515, -4.687465),
            new FsLatLonPoint(39.019832, -6.427709),
            new FsLatLonPoint(39.158189, -6.560815)
        };
        FsLatLonPolygon sector1 = new FsLatLonPolygon(sector1pol);

I have this code but fail.

Compile error CS0236 A field initializer cannot reference the non-static field, method, or property 'name'.

 

[Paul Henty]

You've probably got this code at the class level, rather than inside a method.

You can't use variables (sector1pol) to initialise other variables at the class level (sector1). 

If you need these variable at the class (form) level then easiest fix is to move the initialisation into the constructor of the class. e.g. if it's a form do this:

        private FsLatLonPoint[] sector1pol;
        private FsLatLonPolygon sector1;

        public Form1()
        {
            InitializeComponent();
            this.sector1pol = new FsLatLonPoint[]
            {
                new FsLatLonPoint(39.158189, -6.560815),
                new FsLatLonPoint(39.44173, -6.291623),
                new FsLatLonPoint(39.847553, -4.565154),
                new FsLatLonPoint(39.594515, -4.687465),
                new FsLatLonPoint(39.019832, -6.427709),
                new FsLatLonPoint(39.158189, -6.560815)
            };
            this.sector1 = new FsLatLonPolygon(sector1pol);
        }

Paul