[ARX] 初学者求救大虾帮忙,急!!谢谢!!

chjh_721

#include "math.h"
//#include"gept2dar.h"
#include"geline2d.h"
//#include"acarray.h"
#include"gepnt2d.h"
#include"gelnsg2d.h"

//以下为计算凸多边形面积方法  
double areaofchimb(AcGePoint2dArray&ptarr)
{
AcGePoint2d *p=&ptarr.at(0);
   int i;
  int n;//点的个数
 
  n=ptarr.length();
  AcGePoint2d startpoint=ptarr.first();
  AcGePoint2d endpoint=ptarr.last();

//求顶点到其余点的对角线长
 double*arry=new double[n-3];

 for(i=0;i<n-3;i++)
//    arry=(ptarr.at(0)).distanceTo(ptarr.at(i+2));
arry=ptarr[0].distanceTo(ptarr[i+2]);
//求面积
    double area=0;
 int j=0;
  for(j=0;j<n-2;j++)
  { double a;
 a=startpoint.distanceTo(ptarr[j+1]);
 // a=ads_distance(ptarr[0],ptarr[j+1]);
 double b;
    b=(ptarr[j+1]).distanceTo(ptarr[j+2]);
// b=ads_distance(ptarr[j+1],ptarr[j+2]);
    double d;
    if (j<n-3)
  d=arry[j];
  else
    d=startpoint.distanceTo(endpoint);
//   d=ads_distance(ptarr[0],ptarr[n-1]);
    double c=(a+b+d)/2;
    double s=sqrt(c*(c-a)*(c-b)*(c-d));
    area+=s;
  }
 return area; 
}

//计算多边形面积        ！！需要修改，补凸的时候可能使临近两点变凹  
double area(AcGePoint2dArray &ptarr)
{ 
 bool  PointInPolygon(AcGePoint2d& pt,AcGePoint2dArray &ptarr);
    double areaoftriangle(AcGePoint2d ,AcGePoint2d,AcGePoint2d );
    int n;//点的个数
 n=4;
    ptarr.at(0).set(10,10);
    ptarr.at(1).set(10,20);
    ptarr.at(2).set(20,20);
    ptarr.at(3).set(20,10);

 double area=0;
    double s=0;
    int i;
 for(i=0;i<n;i++)
 {double s=0;
 AcGePoint2d*ppt=new AcGePoint2d(ptarr.at(i));
    ptarr.removeAt(i);
    bool flag;
 flag=PointInPolygon(*ppt,ptarr);
  if(flag==true) ptarr.insertAt(i,*ppt);
  else
   {AcGeLine2d*line=new AcGeLine2d(ptarr.at((i-1+n-1)%(n-1)),ptarr.at((i+n-1)%(n-1)));
  
    AcGePoint2d newpoint=(*ppt).mirror(*line);
       ptarr.insertAt(i,newpoint);
    s=s-2*(areaoftriangle(ptarr.at((n+i-1)%n),ptarr.at(i),ptarr.at((n+i+1)%n)));
   }
 }
 area=areaofchimb(ptarr);
 area=area-s;
 return area;

}

//以下判断点是否在多边形中，在返回false ,不在返回true    
bool  PointInPolygon(AcGePoint2d& pt,AcGePoint2dArray &ptarr)
{
 int n = ptarr.length();
    int i, count=0;                               
 double yup, xup, ydown, xdown;
// double y0, x0;
 double t;
 for( i=0; i< n; i++ )
 {
  if((pt.x ==(ptarr.at(i).x)&&(pt.y==ptarr.at(i).y)             //！！检查括号匹配不？？
   || (pt.x==(ptarr.at((i+1)%n).x))&&(pt.y==(ptarr.at((i+1)%n).y))))
        return true;
 xup=(ptarr.at(i)).x>(ptarr.at((i+1)%n).x)?(ptarr.at(i)).xptarr.at((i+1)%n).x);
 yup=(ptarr.at(i)).y>(ptarr.at((i+1)%n).y)?(ptarr.at(i)).yptarr.at((i+1)%n).y);
 xdown=(ptarr.at(i)).x<(ptarr.at((i+1)%n).x)?(ptarr.at(i)).xptarr.at((i+1)%n).x);
 ydown=yup=(ptarr.at(i)).y<(ptarr.at((i+1)%n).y)?(ptarr.at(i)).yptarr.at((i+1)%n).y);
   if(pt.y>yup)
    continue;
   if(pt.y<ydown)
    continue;
   if(pt.y==ydown)
     if(pt.y<yup&&pt.x<xdown)  count++;
  else continue;
   if(pt.y<yup&&pt.y>ydown)
    double  t=xdown+(pt.y-ydown)*(xup-xdown)/(yup-ydown);
 if(t>pt.x)  count++;
 if(t=pt.x)  return true;
 }
  if(count%2==0)  return false;
  else
   return true;
}

//计算三角形面积 
 double areaoftriangle(AcGePoint2d pt1,AcGePoint2d pt2,AcGePoint2d pt3)
 {
  double a,b,c,l,s;
     a=pt1.distanceTo(pt2);
     b=pt2.distanceTo(pt3);
     c=pt3.distanceTo(pt1);
     l=(a+b+c)/2;
     s=sqrt(l*(l-a)*(l-b)*(l-c));
     return s;
 }