Assignment no: 09
//Write a C/C++ program to draw a convex polygons (Square, Rectangle, Triangle) using programmable edges.
#include<iostream>
#include<graphics.h>
using namespace std;

class dline
{
    protected: int x1,y1,x2,y2;
    public:
    dline()
    {
        x1=0,y1=0,x2=0,y2=0;
    }
  
    void drawl()
    {
        float x,y,dx,dy,len;
        int i;
         
        dx=abs(x2-x1);
        dy=abs(y2-y1);
     
        if(dx >= dy)
        {

            len=dx;
        }
        else
        {
            len=dy;
        }

        dx=(x2-x1)/len;
        dy=(y2-y1)/len;

        x = x1 + 0.5;
        y = y1 + 0.5;     

        i=1;

        while(i<=len)
        {
            putpixel(x,y,15);
            x = x + dx;
            y = y + dy;
            i = i + 1;     
        }

        putpixel(x,y,15);

    }
};

class poly: public dline  //poly
{
    private: int a[10][2],p;
    public:
    void setpts(int i)
    {
        int j;
        for(j=0;j<i;j++)
        {
        cout<<"\n Enter x-coordinate: "<<j<<":";cin>>a[j][0];
        cout<<"\n Enter y-coordinate: "<<j<<":";cin>>a[j][1];
        }
    } 
    void drawpoly(int i)
    {
        int j;
        x1=a[0][0];
        y1=a[0][1];     
        x2=a[1][0];
        y2=a[1][1]; 
        dline::drawl();
     
        for(j=0;j<i-1;j++)
        {
        x1=a[j][0];
        y1=a[j][1];     
        x2=a[j+1][0];
        y2=a[j+1][1];
        dline::drawl();
        }

        x1=a[j][0];
        y1=a[j][1];     
        x2=a[0][0];
        y2=a[0][1];
        dline::drawl();
    }
}; 

int main()
{ 
    int n ,gd=DETECT,gm=VGAMAX;
    initgraph(&gd,&gm,NULL);
     
    poly shape;
           
     cout<<"\nEnter number of slides: "; cin>>n;
     shape.setpts(n);
    shape.drawpoly(n);
    delay(3000);
    getch();
    closegraph();
    return 0;
}