开发笔记:建筑物多边形化简系列之去除冗余点

// 去除冗余点，zf，0717
void CGeoPolygon::RemoveRedundant(void)
{
for(int i = 0;i {
vector temp; //用于存放冗余点的下标
bool odinary = true; //设定状态，以确定三点单元的首点
int count = 0; //记录删除的点数，一旦有正常情况恢复为0
int ptsNum = circles[i]->pts.size();
for(int n = 0;n {
CMyPoint*first,*middle,*last; //定义三点
if(odinary) //正常，没有冗余点的情况
{
first = circles[i]->pts[n];
middle = circles[i]->pts[n+1];
last = circles[i]->pts[n+2];
}
else //不正常，存在冗余点的情况
{
first = circles[i]->pts[n-count]; //存在冗余点，删除后判断冗余点之后的点是否为冗余点还需要之前三点单元的首点
middle = circles[i]->pts[n+1];
last = circles[i]->pts[n+2];
}
double angle = calAngle(first,middle,last); //计算角度
if(angle >= 10&&angle<=170) //角度阈值设为10°（可根据需要调整）,当角度大于阈值，情况正常，不需要去除点
{
odinary = true;
count = 0; //记录删除的点数，一旦有正常情况恢复为0
}
else // 存在冗余点
{
temp.push_back(n+1); //记录冗余点在circles[i]->pts中下标
odinary = false; //情况不正常
count++; //连续不正常时都要记录
}
}
vector tempPoints; //定义临时点集
if(tempPoints.size()!=0) vector().swap(tempPoints); //防止点集不为空
for(int j = 0;j {
bool answer = isContained(temp,j); //判断j是否存在temp中，若存在说明为冗余点，新点集中不应有此点
if(answer == false) //若不存在说明不为冗余点，新点集应存此点
tempPoints.push_back(circles[i]->pts[j]);
}
tempPoints.swap(circles[i]->pts); //交换，得到去除冗余点之后的环circles[i]->pts
}
}

// 计算三点之间的角度，zf，0717，要#include
double CGeoPolygon::calAngle(CMyPoint* p1, CMyPoint* p2, CMyPoint* p3)
{
double x1 = p1->Getx();
double y1 = p1->Gety();
double x2 = p2->Getx();
double y2 = p2->Gety();
double x3 = p3->Getx();
double y3 = p3->Gety();
double angle,p1p2,p2p3,p1p3;
p1p2 = sqrt(((x1 - x2) * (x1 - x2) + (y1 -y2) * (y1 -y2)));
p2p3 = sqrt(((x3 - x2) * (x3 - x2) + (y3 -y2) * (y3 -y2)));
p1p3 = sqrt(((x1 - x3) * (x1 - x3) + (y1 -y3) * (y1 -y3)));
angle = acos((p1p2 * p1p2 + p2p3 * p2p3 - p1p3 * p1p3) / (2 * p1p2 * p2p3)) * 180.0 / 3.1415926;
if(angle<0)
angle = angle*(-1);
return angle;
}

// 判断某个数是不是在数组中，zf，0717
bool CGeoPolygon::isContained(vector temp, int i)
{
bool answer = false;
for(int j = 0;j {
if(i == temp[j]) answer = true;
if(answer) break;
}
return answer;
}