Well-known binary 格式

  

The OpenGIS Consortium "Simple Features for SQL" specification defines the well-known binary representation. This representation is also defined by the International Organization for Standardization (ISO) "SQL/MM Part: 3 Spatial" standard. See the related reference section at the end of this topic for information on functions that accept and produce the WKB.

 

// Basic Type definitions

// byte : 1 byte

// uint32 : 32 bit unsigned integer (4 bytes)

// double : double precision number (8 bytes)

 

// Building Blocks : Point, LinearRing 

Point

 {

     double x;

     double y;

};

 

LinearRing

{

uint32 numPoints;

Point points[numPoints];

};

 

enum wkbGeometryType

{

     wkbPoint = 1,

     wkbLineString = 2,

     wkbPolygon = 3,

     wkbMultiPoint = 4,

     wkbMultiLineString = 5,

     wkbMultiPolygon = 6

};

 

enum wkbByteOrder

{

     wkbXDR = 0, // Big Endian

     wkbNDR = 1 // Little Endian

};

 

WKBPoint

{

byte byteOrder;

uint32 wkbType; // 1=wkbPoint

Point point;

};

 

WKBLineString

{

     byte byteOrder;

     uint32 wkbType; // 2=wkbLineString

     uint32 numPoints;

     Point points[numPoints];

};

 

WKBPolygon

 {

     byte byteOrder;

     uint32 wkbType; // 3=wkbPolygon

     uint32 numRings;

     LinearRing rings[numRings];

};

 

WKBMultiPoint

{

     byte byteOrder;

     uint32 wkbType; // 4=wkbMultipoint

     uint32 num_wkbPoints;

     WKBPoint WKBPoints[num_wkbPoints];

};

 

WKBMultiLineString

{

     byte byteOrder;

     uint32 wkbType; // 5=wkbMultiLineString

     uint32 num_wkbLineStrings;

     WKBLineString WKBLineStrings[num_wkbLineStrings];

};

 

wkbMultiPolygon

{

     byte byteOrder;

     uint32 wkbType; // 6=wkbMultiPolygon

     uint32 num_wkbPolygons;

     WKBPolygon wkbPolygons[num_wkbPolygons];

};

 

WKBGeometry

{

     union

     {

          WKBPoint point;

          WKBLineString linestring;

          WKBPolygon polygon;

          WKBMultiPoint mpoint;

          WKBMultiLineString mlinestring;

          WKBMultiPolygon mpolygon;

     }

};

 

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