Visual Studio 2010 — Как извлечь вершины геометрии из шейп-файлов ESRI, используя библиотеку ogr со Stack Overflow

Я нашел ответ:
Вы должны позаботиться о некоторой информации о шейп-файлах ESRI.

• Точечный слой : Может иметь только функции типа wkbpoint. Таким образом, вы можете определить структуру данных с именем MyPoint2D и хранить
  координаты этого слоя в векторе с членами типа
  MyPoint2D.

• Многоточечный слой : Может иметь только функции типа wkbMultipoint. Таким образом, вы можете хранить каждую функцию в вектор с членами типа MyPoint2D и коллекция таких векторов будет содержать координаты всех объектов в слое.

• Слой полилинии : Может иметь особенности типа wkbLineString а также wkbMultiLineString. Таким образом, вы можете иметь структуру данных MyLine2D, который является вектором с MyPoint2D члены и вектор с членами типа MyLine2D будет держать
  LineFeature и, наконец, объекты в слое будут сохранены в векторе с членами типа LineFeature.

• Многоугольный слой : О полигонах вы должны знать, что каждый полигон состоит из Внешнее кольцо и несколько интерьер
  кольца (это была моя настоящая проблема, которая заставила меня спросить
  вопрос). А также слой может иметь особенности типа
  wkbPolygon а также wkbMultiPolygon.

Итак, сначала мы должны определить эти структуры данных:

//data structure for points
typedef struct MyPoint2D
{
double dX;
double dY;
}MyPoint2D;

//Holds Coordinates of Point Shapefile
vector<MyPoint2D>PointLayer;

//data structure for a multipoint feature
typedef struct MultipointFeature
{
vector<MyPoint2D>PointsOfFeature;
}MultipointFeature;

//Holds Coordinates of multiPoint Shapefile
vector<MultipointFeature> MultipointLayer;

//data structure for lines
typedef struct MyLine2D
{
vector<MyPoint2D> LineString;
}MyLine2D;

//data structure for a line feature
typedef struct LineFeature
{
vector<MyLine2D>LinesOfFeature;
}LineFeature;

//Holds Coordinates of Line Shapefile
vector<LineFeature> LineLayer;

//data structure for rings
typedef struct MyRing2D
{
vector<MyPoint2D> RingString;
bool IsClockwised;
}MyRing2D;

//data structure for polygons
typedef struct MyPolygon2D
{
vector<MyRing2D>Polygon;
}MyPolygon2D;

//data structure for a polygon feature
typedef struct PolygonFeature
{
vector<MyPolygon2D>PolygonsOfFeature;
}PolygonFeature;

//Holds Coordinates of Polygon Shapefile
vector<PolygonFeature> PolygonLayer;

//data structure to hold bounding box
typedef struct SBoundingBox
{
float fMaxX;
float fMaxY;
float fMinX;
float fMinY;
}SBoundingBox;

//Bounding Box of Shapefile
SBoundingBox sBoundingBox;

И это весь код, который я использовал для извлечения координат вершин в шейп-файлах ESRI:

void OpenShapeFile(char* filename)
{
OGRErr error;
OGRDataSource *poDataSource;
poDataSource = OGRSFDriverRegistrar::Open(filename,false);
OGRLayer *poLayer;
poLayer = poDataSource ->GetLayer(0);
OGREnvelope Envelope;
error = poLayer ->GetExtent(&Envelope,true);
sBoundingBox.fMaxX = Envelope.MaxX;
sBoundingBox.fMaxY = Envelope.MaxY;
sBoundingBox.fMinX = Envelope.MinX;
sBoundingBox.fMinY = Envelope.MinY;

OGRwkbGeometryType LayerGeometryType = poLayer ->GetGeomType();
int NumberOfFeatures = poLayer ->GetFeatureCount(true);
poLayer ->ResetReading();

//Point Shapefile
if ( wkbFlatten ( LayerGeometryType ) == wkbPoint )
{
OGRFeature *poFeature;
for ( int i = 0; i < NumberOfFeatures; i++ )
{
poFeature = poLayer ->GetNextFeature();
OGRGeometry *poGeometry;
poGeometry = poFeature ->GetGeometryRef();
if ( poGeometry != NULL && wkbFlatten ( poGeometry ->getGeometryType() ) == wkbPoint )
{
OGRPoint *poPoint = ( OGRPoint * )poGeometry;
MyPoint2D pt;
pt.dX = poPoint ->getX();
pt.dY = poPoint ->getY();
PointLayer.push_back(pt);
}
OGRFeature::DestroyFeature(poFeature);
}
}

//Multipoint Shapefile
if ( wkbFlatten ( LayerGeometryType ) == wkbMultiPoint )
{
OGRFeature *poFeature;
MultipointFeature MultiPoint;
for ( int i = 0; i < NumberOfFeatures; i++ )
{
poFeature = poLayer ->GetNextFeature();
OGRGeometry *poGeometry;
poGeometry = poFeature ->GetGeometryRef();
if ( poGeometry != NULL && wkbFlatten ( poGeometry ->getGeometryType() ) == wkbMultiPoint )
{
OGRMultiPoint *poMultipoint = ( OGRMultiPoint * )poGeometry;
int NumberOfGeometries = poMultipoint ->getNumGeometries();
MultiPoint.PointsOfFeature.resize( NumberOfGeometries );
for ( int j = 0; j < NumberOfGeometries; j++ )
{
OGRGeometry *poPointGeometry = poMultipoint ->getGeometryRef(j);
OGRPoint *poPoint = ( OGRPoint * )poPointGeometry;
MyPoint2D pt;
pt.dX = poPoint ->getX();
pt.dY = poPoint ->getY();
MultiPoint.PointsOfFeature.at(j) = pt;
}
MultipointLayer.push_back(MultiPoint);
}
OGRFeature::DestroyFeature(poFeature);
}
}

//Polyline Shapefile
if ( wkbFlatten ( LayerGeometryType ) == wkbLineString )
{
OGRFeature *poFeature;
LineFeature Polyline;
OGRPoint ptTemp;
for ( int i = 0; i < NumberOfFeatures; i++ )
{
poFeature = poLayer ->GetNextFeature();
OGRGeometry *poGeometry;
poGeometry = poFeature ->GetGeometryRef();
if ( poGeometry != NULL && wkbFlatten ( poGeometry ->getGeometryType() ) == wkbLineString  )
{
OGRLineString *poLineString = ( OGRLineString * )poGeometry;
Polyline.LinesOfFeature.resize(1);
int NumberOfVertices = poLineString ->getNumPoints();
Polyline.LinesOfFeature.at(0).LineString.resize(NumberOfVertices);
for ( int k = 0; k < NumberOfVertices; k++ )
{
poLineString ->getPoint(k,&ptTemp);
MyPoint2D pt;
pt.dX = ptTemp.getX();
pt.dY = ptTemp.getY();
Polyline.LinesOfFeature.at(0).LineString.at(k) = pt;
}
LineLayer.push_back(Polyline);
}
else if ( poGeometry != NULL && wkbFlatten ( poGeometry ->getGeometryType() ) == wkbMultiLineString )
{
OGRMultiLineString *poMultiLineString = ( OGRMultiLineString * )poGeometry;
int NumberOfGeometries = poMultiLineString ->getNumGeometries();
Polyline.LinesOfFeature.resize(NumberOfGeometries);
for ( int j = 0; j < NumberOfGeometries; j++ )
{
OGRGeometry *poLineGeometry = poMultiLineString ->getGeometryRef(j);
OGRLineString *poLineString = ( OGRLineString * )poLineGeometry;
int NumberOfVertices = poLineString ->getNumPoints();
Polyline.LinesOfFeature.at(j).LineString.resize(NumberOfVertices);
for ( int k = 0; k < NumberOfVertices; k++ )
{
poLineString ->getPoint(k,&ptTemp);
MyPoint2D pt;
pt.dX = ptTemp.getX();
pt.dY = ptTemp.getY();
Polyline.LinesOfFeature.at(j).LineString.at(k) = pt;
}
}
LineLayer.push_back(Polyline);
}
OGRFeature::DestroyFeature(poFeature);
}
}

//Polygon Shapefile
if ( wkbFlatten ( LayerGeometryType ) == wkbPolygon )
{
OGRFeature *poFeature;
PolygonFeature Polygon;
OGRPoint ptTemp;
for ( int i = 0; i < NumberOfFeatures; i++ )
{
poFeature = poLayer ->GetNextFeature();
OGRGeometry *poGeometry;
poGeometry = poFeature ->GetGeometryRef();
if ( poGeometry != NULL && wkbFlatten ( poGeometry ->getGeometryType() ) == wkbPolygon )
{
OGRPolygon *poPolygon = ( OGRPolygon * )poGeometry;
Polygon.PolygonsOfFeature.resize(1);
int NumberOfInnerRings = poPolygon ->getNumInteriorRings();
OGRLinearRing *poExteriorRing = poPolygon ->getExteriorRing();
Polygon.PolygonsOfFeature.at(0).Polygon.resize(NumberOfInnerRings+1);
Polygon.PolygonsOfFeature.at(0).Polygon.at(0).IsClockwised = poExteriorRing ->isClockwise();
int NumberOfExteriorRingVertices = poExteriorRing ->getNumPoints();
Polygon.PolygonsOfFeature.at(0).Polygon.at(0).RingString.resize(NumberOfExteriorRingVertices);
for ( int k = 0; k < NumberOfExteriorRingVertices; k++ )
{
poExteriorRing ->getPoint(k,&ptTemp);
MyPoint2D pt;
pt.dX = ptTemp.getX();
pt.dY = ptTemp.getY();
Polygon.PolygonsOfFeature.at(0).Polygon.at(0).RingString.at(k) = pt;
}
for ( int h = 1; h <= NumberOfInnerRings; h++ )
{
OGRLinearRing *poInteriorRing = poPolygon ->getInteriorRing(h-1);
Polygon.PolygonsOfFeature.at(0).Polygon.at(h).IsClockwised = poInteriorRing ->isClockwise();
int NumberOfInteriorRingVertices = poInteriorRing ->getNumPoints();
Polygon.PolygonsOfFeature.at(0).Polygon.at(h).RingString.resize(NumberOfInteriorRingVertices);
for ( int k = 0; k < NumberOfInteriorRingVertices; k++ )
{
poInteriorRing ->getPoint(k,&ptTemp);
MyPoint2D pt;
pt.dX = ptTemp.getX();
pt.dY = ptTemp.getY();
Polygon.PolygonsOfFeature.at(0).Polygon.at(h).RingString.at(k) = pt;
}
}
PolygonLayer.push_back(Polygon);
}
else if ( poGeometry != NULL && wkbFlatten ( poGeometry ->getGeometryType() ) == wkbMultiPolygon )
{
OGRMultiPolygon *poMultiPolygon = ( OGRMultiPolygon * )poGeometry;
int NumberOfGeometries = poMultiPolygon ->getNumGeometries();
Polygon.PolygonsOfFeature.resize(NumberOfGeometries);
for ( int j = 0; j < NumberOfGeometries; j++ )
{
OGRGeometry *poPolygonGeometry = poMultiPolygon ->getGeometryRef(j);
OGRPolygon *poPolygon = ( OGRPolygon * )poPolygonGeometry;
int NumberOfInnerRings = poPolygon ->getNumInteriorRings();
OGRLinearRing *poExteriorRing = poPolygon ->getExteriorRing();
Polygon.PolygonsOfFeature.at(j).Polygon.resize(NumberOfInnerRings+1);
Polygon.PolygonsOfFeature.at(j).Polygon.at(0).IsClockwised = poExteriorRing ->isClockwise();
int NumberOfExteriorRingVertices = poExteriorRing ->getNumPoints();
Polygon.PolygonsOfFeature.at(j).Polygon.at(0).RingString.resize(NumberOfExteriorRingVertices);
for ( int k = 0; k < NumberOfExteriorRingVertices; k++ )
{
poExteriorRing ->getPoint(k,&ptTemp);
MyPoint2D pt;
pt.dX = ptTemp.getX();
pt.dY = ptTemp.getY();
Polygon.PolygonsOfFeature.at(j).Polygon.at(0).RingString.at(k) = pt;
}
for ( int h = 1; h <= NumberOfInnerRings; h++ )
{
OGRLinearRing *poInteriorRing = poPolygon ->getInteriorRing(h-1);
Polygon.PolygonsOfFeature.at(j).Polygon.at(h).IsClockwised = poInteriorRing ->isClockwise();
int NumberOfInteriorRingVertices = poInteriorRing ->getNumPoints();
Polygon.PolygonsOfFeature.at(j).Polygon.at(h).RingString.resize(NumberOfInteriorRingVertices);
for ( int k = 0; k < NumberOfInteriorRingVertices; k++ )
{
poInteriorRing ->getPoint(k,&ptTemp);
MyPoint2D pt;
pt.dX = ptTemp.getX();
pt.dY = ptTemp.getY();
Polygon.PolygonsOfFeature.at(j).Polygon.at(h).RingString.at(k) = pt;
}
}
}
PolygonLayer.push_back(Polygon);
}
}
OGRFeature::DestroyFeature(poFeature);
}

OGRDataSource::DestroyDataSource(poDataSource);
}