I have used a Polygon Shapefile using Shapelib in OpenGL.When I used States.shp(attachment) I get some unwanted additional edges.
#include
#include
#include "shapelib\shapefil.h"
#include
using namespace std;
typedef struct MyPoint2D
{
double dX;
double dY;
}MyPoint2D;
//Holds Coordinates of Point Shapefile
vector vPoints;
typedef struct MyLineString2D
{
vector vPointList;
}MyLineString2D;
//Holds Coordinates of Line Shapefile
vector vLines;
typedef struct MyPolygon2D
{
vector vPointList;
}MyPolygon2D;
//Holds Coordinates of Polygon Shapefile
vector vPolygons;
typedef struct SBoundingBox
{
float fMaxX;
float fMaxY;
float fMinX;
float fMinY;
}SBoundingBox;
//Bounding Box of Shapefile
SBoundingBox sBoundingBox;
//Function to Open Shapefile and parse the info
void OpenShapeFile(char* fileName)
{
SHPHandle hSHP=SHPOpen(fileName, "rb" );
//Read Bounding Box of Shapefile
sBoundingBox.fMaxX=hSHP->adBoundsMax[0];
sBoundingBox.fMaxY=hSHP->adBoundsMax[1];
sBoundingBox.fMinX=hSHP->adBoundsMin[0];
sBoundingBox.fMinY=hSHP->adBoundsMin[1];
if(hSHP == NULL) return;
//Point Shapefile
if(hSHP->nShapeType == SHPT_POINT)
{
SHPObject *psShape;
for(int i=0;inRecords;i++)
{
psShape = SHPReadObject(hSHP, i);
double fX = psShape->padfX[0];
double fY = -psShape->padfY[0];
//Plot these points
MyPoint2D pt;
pt.dX=fX;
pt.dY=-fY;
vPoints.push_back(pt);
}
}
//Line Shapefile
else if(hSHP->nShapeType == SHPT_ARC)
{
SHPObject *psShape;
for(int i=0;inRecords;i++)
{
psShape = SHPReadObject(hSHP, i);
vector tempPointArray;
for(int j=0;jnVertices;j++)
{
double fX = psShape->padfX[j];
double fY = psShape->padfY[j];
MyPoint2D pt;
pt.dX=fX;
pt.dY=fY;
tempPointArray.push_back(pt);
}
MyLineString2D linestring;
linestring.vPointList=tempPointArray;
vLines.push_back(linestring);
}
}
//Polygon Shapefile
if(hSHP->nShapeType == SHPT_POLYGON)
{
SHPObject *psShape;
for(int i=0;inRecords;i++)
{
psShape = SHPReadObject(hSHP, i);
vector tempPointArray;
for(int j=0;jnVertices;j++)
{
double fX = psShape->padfX[j];
double fY = psShape->padfY[j];
MyPoint2D pt;
pt.dX=fX;
pt.dY=fY;
tempPointArray.push_back(pt);
}
MyPolygon2D polygon;
polygon.vPointList=tempPointArray;
vPolygons.push_back(polygon);
}
}
}
void draw()
{
glClear (GL_COLOR_BUFFER_BIT);
glColor3f (0.0, 0.0, 1.0);
glLoadIdentity ();
//Render Point Shapefile
glColor3f (0.0, 0.0, 1.0);
glEnable(GL_POINT_SMOOTH) ;
glPointSize(5.0);
glBegin(GL_POINTS);
for(int i=0;i
//OpenShapeFile("States\\states.shp");//Polygon Shapefile
I get the output as follows when I tried to render.Observe the yellow circled areas.
But there is no problem when the same file is opened in softwares like Sharpmap which also use shapelib.
What could be the problem ?States.zip
