计算几何模板1 点部分

//Computational Geometry 1 points
//by kevin_samuel(fenice) Soochow University 2011
//kevin.samuel.sun@gmail.com
//kevin-samuel.myazure.org
//temple
#include <iostream>
#include <cmath>
#include <algorithm>
#include <cstdio>

using namespace std;

//define
const double EPS = 1e-8;
const double PI = acos(-1.0);

//point
class Point
{
public:
double x;
double y;
Point(){};
Point(double x,double y):x(x),y(y){};

//operator
//operator=
Point& operator=(const Point& _P)
{
x = _P.x;
y = _P.y;
return *this;
}
//operator*
double operator*(const Point& _P)const
{
return x*_P.y - y *_P.x;
}
//operator-
Point operator-(const Point& _P)const
{
return Point(x - _P.x,y - _P.y);
}
//operator==
bool operator==(const Point& _P)const
{
if(fabs(_P.x - x) < EPS && fabs(_P.y - y) < EPS)
return true;
else
return false;
}
bool operator!=(const Point& _P)const
{
return ((*this) == _P) == false;
}

//dot product
static double dotProduct(Point s1,Point e1,Point s2,Point e2)
{
double result = 0;
double x1 = e1.x - s1.x;
double y1 = e1.y - s1.y;
double x2 = e2.x - s2.x;
double y2 = e2.y - s2.y;

result = x1*x2 + y1*y2;
return result;
}

//cross product 1 (4 point-type params)
static double crossProduct(Point s1,Point e1,Point s2,Point e2)
{
double result = 0;
double x1 = e1.x - s1.x;
double y1 = e1.y - s1.y;
double x2 = e2.x - s2.x;
double y2 = e2.y - s2.y;

result = x1*y2 - x2*y1;

return result;
}

//cross product 2 (3 point-type params)
static double crossProduct(Point p1,Point p2,Point p0)
{
return crossProduct(p0,p1,p0,p2);
}

//Is on segment or line
static bool onSegment(Point Pi,Point Pj,Point Q)
{
if(Q.x >= min(Pi.x,Pj.x) && Q.x <= max(Pi.x,Pj.x) &&
Q.y >= min(Pi.y,Pj.y) && Q.y <= max(Pi.y,Pj.y) &&
crossProduct(Q,Pj,Pi) == 0
)
return true;
else
return false;
}

//Is on segment
bool IsOnSegment(Point Pi,Point Pj)
{
if(this->x >= min(Pi.x,Pj.x) && this->x <= max(Pi.x,Pj.x) &&
this->y >= min(Pi.y,Pj.y) && this->y <= max(Pi.y,Pj.y) &&
Point::crossProduct(*this,Pj,Pi) == 0
)
return true;
else
return false;
}

//Is inside triangle
bool inTriangle(Point A,Point B,Point C)
{

double Sabc = fabs(Point::crossProduct(B,C,A));
double Spab = fabs(Point::crossProduct(A,B,(*this)));
double Spac = fabs(Point::crossProduct(A,C,(*this)));
double Spbc = fabs(Point::crossProduct(B,C,(*this)));

if(Spbc + Spab + Spac == Sabc)
return true;
else
return false;
}

//Is inside polygon
//polys[] ,0-n
bool insidePolygon(Point *polys,int n)
{
int counter = 0;
double xinters;
Point p1,p2;
p1 = polys[0];
for(int i = 1; i < n; i++)
{
p2 = polys[i % n];
if(Point::onSegment(p1,p2,(*this)) == true)
return true;
if((*this).y > min(p1.y,p2.y) && (*this).y <= max(p1.y,p2.y))
{
if((*this).x <= max(p1.x,p2.x) && p1.y != p2.y)
{
xinters = ((*this).y - p1.y)*(p2.x - p1.x)/(p2.y - p1.y) + p1.x;
if(p1.x == p2.x || (*this).x <= xinters)
counter++;
}
}
p1 = p2;
}
if(counter % 2 == 0)
return false;
return true;
}

//distance^2
double dis2(const Point& _P)const
{
return (x - _P.x)*(x - _P.x) + (y - _P.y)*(y - _P.y);
}
//distance
double dis(const Point& _P)const
{
return sqrt(dis2(_P));
}

};

//test zone
int main()
{
//
return 0;
}