#include <iostream.h>
#include <fstream.h>
#include <math.h>
#include <graphics.h>
#include "polygon.h"

Polygon::Polygon(int n): num_vertices(n) {
   int i;
   vertices = new point[num_vertices];
   centre.x = centre.y = 0.0;
   for (i=0;i<num_vertices;i++) {
      cout << "Enter (x,y) coords for vertex " << (i+1) << ": ";
      cin >> vertices[i].x >> vertices[i].y;
      centre.x += vertices[i].x;
      centre.y += vertices[i].y;
   }
   centre.x /= num_vertices;
   centre.y /= num_vertices;
}

Polygon::Polygon(char *name) {
   int i;
   ifstream ins(name);
   if (ins.fail()) {
      cerr << "Error opening " << name << endl;
      num_vertices = 0;
   }
   else {
      ins >> num_vertices;
      vertices = new point[num_vertices];
       for (i=0;i<num_vertices;i++) {
         ins >> vertices[i].x >> vertices[i].y;
      }
      ins >> centre.x >> centre.y;
      ins.close();
   }
}

Polygon::Polygon(const Polygon& p): num_vertices(p.num_vertices) {
   int i;
   vertices = new point[num_vertices];
   for (i=0;i<num_vertices;i++)
      vertices[i] = p.vertices[i];
   centre = p.centre;
}

Polygon::~Polygon() {
   delete [] vertices;
}

void Polygon::translate(float dx, float dy) {
   int i;
   for (i=0;i<num_vertices;i++) {
      vertices[i].x += dx;
      vertices[i].y += dy;
   }
   centre.x += dx;
   centre.y += dy;
}

void Polygon::scale(float sx, float sy) {
   point  temp=centre;
   int   i;
   translate(-temp.x,-temp.y);
   for (i=0;i<num_vertices;i++) {
      vertices[i].x *= sx;
      vertices[i].y *= sy;
   }
   translate(temp.x,temp.y);
}

void Polygon::rotate(float angle) {
   float  theta =  angle*M_PI/180.0;
   point  temp=centre, p;
   int   i;
   translate(-temp.x,-temp.y);
   for (i=0;i<num_vertices;i++) {
      p.x = vertices[i].x*cos(theta) + vertices[i].y*sin(theta);
      p.y = -vertices[i].x*sin(theta) + vertices[i].y*cos(theta);
      vertices[i] = p;
   }
   translate(temp.x,temp.y);
}

void Polygon::draw() {
   int i;
   moveto(vertices[num_vertices-1].x,vertices[num_vertices-1].y);
   for (i=0;i<num_vertices;i++)
      lineto(vertices[i].x,vertices[i].y);
}