#include  
 #include  
 #include  
 #include  
 #include  
 class algo  
 {  
   float x1,x2,y1,y2;  
   public:  
   int sign(float a)  
   {  
   if(a>0)  
     return 1;  
   if(a<0)  
     return -1;  
   return 0;  
   }  
 void dda(float,float,float,float);  
 void br_line(float,float,float,float);  
 void br_c(float,float,float);  
 };  
 void main()  
 {  
   algo a;  
   int ch,gdriver=DETECT,gmode;  
   initgraph(&gdriver,&gmode,"c:\\tc\\bgi");  
   do  
   {  
     cleardevice();  
     cout<< "\n\t\t\t#### MAIN MENU ####";  
     cout<< "\n\t\t1.DDA LINE DRAWING ALGORITHM";  
     cout<< "\n\t\t2.BRESENHAM LINE DRAWIG ALGORITHM";  
     cout<< "\n\t\t3.BRESENHAM CIRCLE DRAWNG ALGORITHM";  
     cout<< "\n\t\t4.EXIT";  
     cout<< "\n\t\tENTER UR CHOICE:";  
     cin>> ch;  
     clrscr();  
     switch(ch)  
     {  
       case 1:  float x2,x1,y2,y1;  
         cout<< "\n\t\tDDA LINE DRAWING ALGO";  
         cout<< "\n\tEnter (x1,y1) co-ordinates of first point:";  
         cin>>x1>>y1;  
         cout<< "\n\tEnter (x2,y2) co-ordinates. of last point:";  
         cin>>x2>>y2;  
         a.dda(x1,y1,x2,y2);  
         getch();  
         break;  
       case 2:  cout<< "\n\t\tBRESENHAM LINE DRAWIG ALGO";  
         cout<< "\n\tEnter (x1,y1) co-ordinates of first point";  
         cin>>x1>>y1;  
         cout<< "\n\tEnter (x2,y2) co-ordinates of end point";  
         cin>>x2>>y2;  
         a.br_line(x1,y1,x2,y2);  
         getch();  
         break;  
       case 3:  cout<< "\n\t\tBRESENHAM CIRCLE DRAWNG ALGO";  
         cout<< "\n\tEnter center co-ordinates.";  
         cin>>x1>>y1;  
         float r;  
         cout<< "\n\tEnter radius";  
         cin>>r;  
         a.br_c(x1,y1,r);  
         getch();  
         break;  
       case 4:  break;  
       default:cout<< "\t\tInvalid Choice\n";  
         getch();  
         break;  
     }  
   }while(ch!=4);  
   closegraph();  
 }  
 void algo:: dda(float x1,float y1,float x2,float y2)  
 {  
   float dx,dy,len,i,xn,yn,x,y,midx,midy;  
   midx=getmaxx()/2;  
   midy=getmaxy()/2;  
   line(0,midy,2*midx,midy);  
   line(midx,0,midx,2*midy);  
   x1+=midx;  
   y1=-y1;  
   y1+=midy;  
   x2+=midx;  
   y2=-y2;  
   y2+=midy;  
   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*sign(dx);  
   y=y1+0.5*sign(dy);  
   putpixel(x,y,WHITE);  
   i=1;  
   while(i<=len)  
   {  
     putpixel(x,y,RED);  
     x=x+dx;  
     y=y+dy;  
     i++;  
   }  
   getch();  
 }  
 void algo:: br_line(float x1,float y1,float x2,float y2)  
 {  
   float dx,dy,s1,s2,e,i,change,x,y,midx,midy,x3,y3,exch;  
   midx=getmaxx()/2;  
   midy=getmaxy()/2;  
   line(0,midy,2*midx,midy);  
   line(midx,0,midx,2*midy);  
   x1+=midx;  
   y1=-y1;  
   y1+=midy;  
   x2+=midx;  
   y2=-y2;  
   y2+=midy;  
   x=abs(x2-x1);  
   y=abs(y2-y1);  
   x3=x1;  
   y3=y1;  
   s1=sign(x2-x1);  
   s2=sign(y2-y1);  
   e=2*y-x;  
   if(y>x)  
   {  
     int temp=x;  
     x=y;  
     y=temp;  
     exch=1;  
   }  
   else  
     exch=0;  
   i=1;  
   while(i<=x)  
   {  
     putpixel(x3,y3,WHITE);  
     while(e>=0)  
     {  
       if(exch==1)  
         x3+=s1;  
       else  
         y3+=s2;  
       e=e-2*x;  
     }  
     if(exch==1)  
       y3+=s2;  
     else  
       x3+=s1;  
     e=e+2*y;  
     i++;  
   }  
 }  
 void algo:: br_c(float a,float b,float r)  
 {  
   float d,x,y,midx,midy;  
   midx=getmaxx()/2;  
   midy=getmaxy()/2;  
   line(0,midy,2*midx,midy);  
   line(midx,0,midx,2*midy);  
   x+=midx;  
   y=-y;  
   y+=midy;  
   x1=0,y1=r;  
   d=3-2*r;  
   while(x1<=y1)  
   {  
     if(d<0)  
     {  
       d=d+4*x1+6;  
     }  
     else  
     {  
       d=d+4*(x1-y1)+10;  
       y1=y1-1;  
     }  
     x1=x1+1;  
     putpixel(x1+a+(getmaxx()/2),y1+b+(getmaxy()/2),BLUE);  
     putpixel(y1+a+(getmaxx()/2),x1+b+(getmaxy()/2),BLUE);  
     putpixel(-x1+a+(getmaxx()/2),-y1+b+(getmaxy()/2),BLUE);  
     putpixel(-x1+a+(getmaxx()/2),y1+b+(getmaxy()/2),BLUE);  
     putpixel(y1+a+(getmaxx()/2),-x1+b+(getmaxy()/2),BLUE);  
     putpixel(-y1+a+(getmaxx()/2),x1+b+(getmaxy()/2),BLUE);  
     putpixel(x1+a+(getmaxx()/2),-y1+b+(getmaxy()/2),BLUE);  
     putpixel(-y1+a+(getmaxx()/2),-x1+b+(getmaxy()/2),BLUE);  
   }  
 }