What is Equal SQL Function or StoredProcedure for my C# Method

Question

I have this C# Method that Determine that a point is inside a polygon or not

C# Method is this:

/// <summary>
/// Determine that a point in inside a polygon or not
/// </summary>
/// <param name="points">Points of Polygon</param>
/// <param name="point">Test Point</param>
/// <returns></returns>    
Public bool IsInside(List<PointF> points,PointF point )
    {
        int i, j,n=points.Count;
        bool c = false;
        for (i = 0, j = n - 1; i < n; j = i++)
        {
            if (((points[i].Y > point.Y) != (points[j].Y > point.Y)) &&
                (point.X <
                 (points[j].X - points[i].X)*(point.Y - points[i].Y)/(points[j].Y - points[i].Y) + points[i].X))
                c = !c;
        }
        return c;
    }

How can i convert this to a SQL Function or StoredProcedure?

An idea: you can pass the list of points as xml data and point as x and y parameters to your function or stored procedure. Inside the stored procedure or function load xml data into table using openxml (in function you would need table variable). Then run select query and put your condition of if block in where clause. — The Shooter
– The Shooter, Commented Sep 14, 2016 at 7:52
So where is the polygon you are comparing your point to? Also, if you look at my answer below, you will see how you can convert a latitude and longitude to a spatial point using the geometry::STGeomFromText function. — iamdave
– iamdave, Commented Sep 14, 2016 at 9:50

iamdave · Accepted Answer · 2016-09-14 09:32:13Z

2

If you have all your polygons stored in your SQL Server database as spatial geometry data types, you can use the spatial functions available in SQL Server 2008R2+ of which there are many (Google is your friend here):

declare @g geometry
set @g = geometry::STGeomFromText('POLYGON((-33.229869 -70.891988
                                           ,-33.251124 -70.476616
                                           ,-33.703094 -70.508045
                                           ,-33.693931 -70.891052
                                           ,-33.229869 -70.891988
                                           ))'
                                 ,0)

DECLARE @h geometry;

SET @h = geometry::STGeomFromText('POINT(-33.3906300 -70.5725020)', 0);
SELECT @g.STContains(@h);

answered Sep 14, 2016 at 9:32

iamdave

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