# 2.1.18.6 ocmath_d_polygon_reorder

## Description

This function test or reorder a polygon.

## Syntax

int ocmath_d_polygon_reorder( UINT nSize, double * px, double * py, bool bCCW = true, bool bTest = false )

## Parameters

nSize
[input] point number of the polygon
px
[input] x-coordinates of the polgyon, it might be modified if bTest=false
py
[input] y-coordinates of the polgyon, it might be modified if bTest=false
bCCW
[input](true) counter-clockwise or (false) clockwise
bTest
[input] (true) just determine the order or (false) try to order it into bCCW; default: false;

## Return

if bTest is false, return 1 if reoder was done,

return 0 if not modified,

return -1 if failed.

if bTest is true, return 1 if bCCW is consistents with polygon,

return 0 if bCCW is inconsistent with polygon,

return -1 if unable to determine.

## Examples

EX1

//This example is to check order(bTest is true)
#include <wks2mat.h>
int ocmath_d_polygon_reorder_ex1()
{
//The polygon in this example is counter-clockwise(CCW)
double dX[]={1,2,3,4,5,6,7,8};
double dY[]={5,4,3,1,3,5,6,9};
UINT nSize = 8;
//nRet=0, because the polygon is inconsistent with bCCW = false, which means clockwise
int nRet = ocmath_d_polygon_reorder(nSize,dX,dY,false,true);
if(0 == nRet)
out_str("This polygon is counter-clockwise");
else if(1 == nRet)
out_str("This polygon is clockwise");
else
return 0;

return 1;
}

EX2

//This example is to reorder(bTest is false)
#include <wks2mat.h>
int ocmath_d_polygon_reorder_ex2()
{
//The polygon in this example is counter-clockwise(CCW)
double dX[]={1,2,3,4,5,6,7,8};
double dY[]={5,4,3,1,3,5,6,9};
UINT nSize = 8;

// nRet = 1, and the polygon will be reordered to clockwise
int nRet = ocmath_d_polygon_reorder(nSize,dX,dY,false);	if(0 == nRet)
out_str("This polygon is not reordered");
else if(1 == nRet)
{
out_str("This polygon is reordered");
printf("The reordered polygon is : \n");
for(int ii =0 ; ii< nSize; ii++)
printf("%f\t%f\n",dX[ii],dY[ii]);
}
else
return 0;

return 1;
}