 # C++ Programming Code Examples

## C++ > Computer Graphics Code Examples

### Implement Slicker Algorithm that avoids Triangulation to Find Area of a Polygon

``` Implement Slicker Algorithm that avoids Triangulation to Find Area of a Polygon 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); } ``` 