80 lines
1.9 KiB
C++
80 lines
1.9 KiB
C++
/*This is a C++ Program to find the area of ploygon using slicker algorithm. The algorithm assumes the usual mathematical convention that positive y points upwards. In computer systems where positive y is downwards (most of them) the easiest thing to do is list the vertices counter-clockwise using the “positive y down” coordinates. The two effects then cancel out to produce a positive area.*/
|
|
|
|
#include <iostream>
|
|
|
|
using namespace std;
|
|
|
|
const int MAXPOLY = 200;
|
|
double EPSILON = 0.000001;
|
|
|
|
class Point
|
|
{
|
|
private:
|
|
public:
|
|
double x, y;
|
|
};
|
|
|
|
class Polygon
|
|
{
|
|
private:
|
|
public:
|
|
Point p[MAXPOLY];
|
|
int n;
|
|
|
|
Polygon()
|
|
{
|
|
for (int i = 0; i < MAXPOLY; i++)
|
|
Point p[i];// = new Point();
|
|
}
|
|
};
|
|
|
|
double area(Polygon p)
|
|
{
|
|
double total = 0;
|
|
for (int i = 0; i < p.n; i++)
|
|
{
|
|
int j = (i + 1) % p.n;
|
|
total += (p.p[i].x * p.p[j].y) - (p.p[j].x * p.p[i].y);
|
|
}
|
|
return total / 2;
|
|
}
|
|
|
|
int main(int argc, char **argv)
|
|
{
|
|
Polygon p;
|
|
cout << "Enter the number of points in Polygon: ";
|
|
cin >> p.n;
|
|
cout << "Enter the coordinates of each point: <x> <y>";
|
|
for (int i = 0; i < p.n; i++)
|
|
{
|
|
cin >> p.p[i].x;
|
|
cin >> p.p[i].y;
|
|
}
|
|
double a = area(p);
|
|
if (a > 0)
|
|
cout << "The Area of Polygon with " << (p.n)
|
|
<< " points using Slicker Algorithm is : " << a;
|
|
else
|
|
cout << "The Area of Polygon with " << p.n
|
|
<< " points using Slicker Algorithm is : " << (a * -1);
|
|
}
|
|
|
|
/*
|
|
|
|
Enter the number of points in Polygon: 4
|
|
Enter the coordinates of each point: <x> <y>
|
|
1 1
|
|
1 6
|
|
6 6
|
|
6 1
|
|
The Area of Polygon with 4 points using Slicker Algorithm is : 25
|
|
|
|
Enter the number of points in Polygon:
|
|
5
|
|
Enter the coordinates of each point: <x> <y>
|
|
1 2
|
|
4 5
|
|
9 8
|
|
3 2
|
|
1 5
|
|
The Area of Polygon with 5points using Slicker Algorithm is : 6.0
|