矩形重叠面积

求两个矩形的重叠面积

问题描述

求解两个矩形的重叠面积

原理

TODO…

code

#include <bits/stdc++.h>

// 求解矩形相交的区间
// 1、矩形的描述： 矩形中间点， 宽一半 行一半


using namespace std;

// 定义更加普遍的rect类

template<typename scale>
class rect{
public:
    scale mMX = 0.;
    scale mMY = 0.;
    scale mhalfW = 0.;
    scale mhalfH = 0.;
    rect(scale _mMX, scale _mMy, scale _mhalfW, scale _mhalfH):
    mMX(_mMX), mMY(_mMy), mhalfW(_mhalfW), mhalfH(_mhalfH){
        // cout << mMX << " " << mMY << " " << mhalfH << " " << mhalfW << endl;   
    }
    ~rect(){}
    vector<pair<scale, scale>> getPoints() const {
        
        auto TopLeft = make_pair(mMX-mhalfH, mMY-mhalfW);
        auto TopRight = make_pair(mMX-mhalfH, mMY+mhalfW);
        auto BottomLeft = make_pair(mMX+mhalfH, mMY-mhalfW);
        auto BottomRight = make_pair(mMX+mhalfH, mMY+mhalfW);
        
        vector<pair<scale, scale>> res = {TopLeft, TopRight, BottomLeft, BottomRight};
        return res;
    }
    bool isInRect(const pair<scale, scale> & in){
        if(abs(mMX - in.first) >= mhalfH) return false;
        if(abs(mMY - in.second) >= mhalfW) return false;
        return true;
    }
    // 求取重叠区域
    scale getIntArea(const rect<scale> & other){
        // 判断有没有交集
        if((abs(mMX - other.mMX) < mhalfH+other.mhalfH) && (abs(mMY - other.mMY) < mhalfW+other.mhalfW)){ // 存在交集计算
            vector<pair<scale, scale>> points = other.getPoints(); // 拿到四个点
            
            // debug 四个点
            // for(auto po : points){
            //     cout << "p (" << po.first << "," << po.second << ")" << endl;
            // }
           
            scale down = min(mMX + mhalfH, points[2].first);
            scale top = max(mMX - mhalfH, points[0].first);
            scale left = max(mMY-mhalfW, points[0].second);
            scale right = min(mMY+mhalfW, points[1].second);
            
            return (right - left)*(down - top);
        }
        return scale(0);// 没有交集
    }
};


int main(int * argc, char ** argv){

    rect<double> r1(0. ,0. , 0.5, 0.5);
    rect<double> r2(1. ,1. , 1., 1.);
    double andVal = r1.getIntArea(r2);
    cout << "r1 & r2 = " << andVal << endl;


    return 0;

}

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