分享一个Objectarx 的凸包算法

#include "stdafx.h"
#include "MyTuBao.h"
#include"MathUtil.h"
MyTuBao::MyTuBao()
{
}

MyTuBao::MyTuBao(AcGePoint3dArray arr)
{
    this->ptArr = arr;
}


MyTuBao::~MyTuBao()
{
    ptArr.removeAll();

}

void   MyTuBao::GetTuBao(AcGePoint3dArray &pArray)
{
    int nums = 0;
    optimizePointsArray(ptArr);
    nums = ptArr.length();
    if (nums > 3) {
        selectMinPoint(ptArr);//寻找最小的点
        quickSort(ptArr, 1, nums - 1);//用来根据极角排序点
        pArray.append(ptArr[0]);
        pArray.append(ptArr[1]);
        pArray.append(ptArr[2]);
        int top = pArray.length() - 1;
        for (int i = 3; i < nums; i++)
        {
            while (xmul(ptArr[i], pArray[top], pArray[top - 1]) >= 0)  //是否左转，是继续判断，不是，就入栈  
            {
                pArray.removeLast();
                top = pArray.length() - 1;
            }
            pArray.append(ptArr[i]);

            top = pArray.length() - 1;
        }

    }
}

void MyTuBao::GetRec(AcGePoint3dArray &pArray){
    selectMinPoint(ptArr);//寻找最小的点
    int nums = 0;
    optimizePointsArray(ptArr);
    nums = ptArr.length();
    quickSort(ptArr, 1, nums - 1);//用来根据极角排序点
    pArray = ptArr;

}
void MyTuBao::optimizePointsArray(AcGePoint3dArray &points, double tol /*= 1.0E-7*/) {
    
    for (int i = points.length() - 1; i > 0; i--)
    {
        for (int j = 0; j < i; j++)
        {
            if (CMathUtil::IsEqual(points[i].x, points[j].x, tol) && CMathUtil::IsEqual(points[i].y, points[j].y, tol))
            {
                points.removeAt(i);
                break;
            }
        }
    }
}

long long  MyTuBao::dist(AcGePoint3d p1, AcGePoint3d p2) //两点距离的平方  
{
    return (p1.x - p2.x)*(p1.x - p2.x) + (p1.y - p2.y)*(p1.y - p2.y);
}

bool MyTuBao::cmp1(AcGePoint3d p1, AcGePoint3d p2)   //找到第一个点，返回 true->p1比较小，false->p2比较小
{
    if (p1.y == p2.y)
        return p1.x<p2.x;
    else
        return p1.y<p2.y;
}

bool MyTuBao::cmp2(AcGePoint3d p1, AcGePoint3d p2, AcGePoint3d pointMin)   //极角排序的比较函数  
{
    if (xmul(p1, p2, pointMin)>0)
        return true; //证明 p1小 选中p1
    else if (xmul(p1, p2, pointMin) == 0 && dist(p1, pointMin)<dist(p2, pointMin))  //相等的按距离近的  
        return true; //证明 p1小 选中p1
    return false;
}

double MyTuBao::xmul(AcGePoint3d p1, AcGePoint3d p2, AcGePoint3d  p0)
{
    return (p1.x - p0.x)*(p2.y - p0.y) - (p2.x - p0.x)*(p1.y - p0.y);
}

void MyTuBao::selectMinPoint(AcGePoint3dArray &s) {
    int nums = s.length();
    int cur = 0;
    AcGePoint3d Min = s[0];
    for (int i = 1; i<nums; i++) {
        if (cmp1(s[i], Min)) {
            Min = s[i];
            cur = i;
        }
    }
    s[cur] = s[0];
    s[0] = Min;
    acutPrintf(L"
寻找后最小点为x=%f,y=%f", s[0].x, s[0].y);
}

void  MyTuBao::quickSort(AcGePoint3dArray &s, int l, int r) {
    if (l< r)
    {
        int i = l, j = r;
        AcGePoint3d x = s[l];
        while (i < j)
        {
            while (i < j && cmp2(x, s[j], s[0])) // 从右向左找第一个小于x的数
                j--;
            if (i < j)
                s[i++] = s[j];
            while (i < j && cmp2(s[i], x, s[0])) // 从左向右找第一个大于等于x的数
                i++;
            if (i < j)
                s[j--] = s[i];
        }
        s[i] = x;
        quickSort(s, l, i - 1); // 递归调用
        quickSort(s, i + 1, r);
    }
}