[gdal-dev] Create a shape file with polygons

[Frank Warmerdam]

On 11-01-18 11:28 AM, Jorge Martin wrote:
> OGRPolygon myPoligon;
>
> tmp = strtok (Line, ":");
>
> szName = string (tmp);
>
>
>         while (tmp != NULL)
>             {
>
>         OGRLinearRing MyRing;// = (OGRLinearRing*)
> OGRGeometryFactory::createGeometry(wkbLinearRing);
>
>          tmp = strtok (NULL, ",");
>
>          if(tmp)
>          {
>
>                 string Coords = string(tmp);
>
>                size_t pos = Coords.find(" ");
>
>                string CoordX = Coords.substr(0,pos);
>                string CoordY = Coords.substr(pos);
>
>                x = atof(CoordX.c_str());
>                 y = atof(CoordY.c_str());
>
> MyRing.addPoint(x,y);
>
>
>          }
>
>          myPoligon.addRing(&MyRing);
>
>      }

Jorge,

The essence of your problem is that you are creating a new
ring for each point instead of creating one ring for the
polygon and adding all the points to that ring before adding
the ring to the polygon.  A slightly altered form of the core
that works looks like:

         OGRPolygon myPoligon;
         OGRLinearRing MyRing;// = (OGRLinearRing*)

         tmp = strtok (Line, ":");
         szName = string (tmp);
         while (tmp != NULL)
         {
             OGRGeometryFactory::createGeometry(wkbLinearRing);

             tmp = strtok (NULL, ",");

             if(tmp)
             {
                 string Coords = string(tmp);

                 size_t pos = Coords.find(" ");

                 string CoordX = Coords.substr(0,pos);
                 string CoordY = Coords.substr(pos);

                 x = atof(CoordX.c_str());
                 y = atof(CoordY.c_str());

                 MyRing.addPoint(x,y);
             }
         }

         myPoligon.addRing(&MyRing);

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | Geospatial Programmer for Rent