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原创于 2018-07-24 10:36:56 发布 · 118 阅读

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本文提供了一个计算几何的基础模板，包括向量操作、点积、叉积等关键算法，并实现了求解三角形内特定交点的功能。

#include<bits/stdc++.h>
using namespace std;
struct Point
{
    double x,y;
    Point(double x=0,double y=0):x(x),y(y){ }
};
typedef Point Vector;
Vector operator - (Point A,Point B)//重载运算符
{
    return Vector(A.x-B.x,A.y-B.y);
}
Vector operator *(Point A,double p)
{
    return Vector(A.x*p,A.y*p);
}
Vector operator + (Point A,Point B)
{
    return Vector(A.x+B.x,A.y+B.y);
}
double Dot(Vector A,Vector B)//点积
{
    return A.x*B.x+A.y*B.y;
}
double Length(Vector A)//向量的模
{
    return sqrt(Dot(A,A));
}
double Cross(Vector A,Vector B)//叉积
{
    return A.x*B.y-B.x*A.y;
}
double Angle(Vector A,Vector B)//向量的夹角
{
    return acos(Dot(A,B) / Length(A) / Length(B));
}
Point GetlineIntersection(Point P,Vector v,Point Q,Vector w)//相交
{
    Vector u=P-Q;
    double t=Cross(w,u)/Cross(v,w);
    return P+v*t;
}
Vector Rotate(Vector A,double rad)//A向量旋转rad，逆时针
{
    return Vector(A.x*cos(rad)-A.y*sin(rad),A.x*sin(rad)+A.y*cos(rad));
}
Point getD(Point A,Point B,Point C)//求交点坐标
{
    Vector v1=C-B;
    double a1=Angle(A-B,v1);
    v1=Rotate(v1,a1/3);
    Vector v2=B-C;
    double a2=Angle(A-C,v2);
    v2=Rotate(v2,-a2/3);
    return GetlineIntersection(B,v1,C,v2);
}
Point read_point()
{
    int x,y;
    scanf("%d %d",&x,&y);
     return Vector(x,y);
}
int main()
{
    int T;
    Point A,B,C,D,E,F;
    scanf("%d",&T);
    while(T--)
    {
        A=read_point();
        B=read_point();
        C=read_point();
        D=getD(A,B,C);
        E=getD(B,C,A);
        F=getD(C,A,B);
        printf("%.6lf %.6lf %.6lf %.6lf %.6lf %.6lf\n",D.x,D.y,E.x,E.y,F.x,F.y); 
    }
    return 0;
}

计算几何的基本模板