Program to draw an ellipse using MidPoint Ellipse Algorithm

 # include <iostream.h>   

# include <graphics.h>   

# include    <conio.h>   

# include     <math.h>  

void show_screen( );   

void midpoint_ellipse(const int,const int,const int,const int);   

int main( )      

{         

int driver=VGA;         

int mode=VGAHI;         

int h=0;         

int k=0;         

int rx=0;         

int ry=0;         

do     

{        

show_screen( );        

gotoxy(8,10);        

cout<<"Central Point of the Ellipse : (h,k) :";        

gotoxy(8,11);        

cout<<"ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ";        

gotoxy(12,13);        

cout<<"Enter the value of h = ";        

cin>>h;        

gotoxy(12,14);        

cout<<"Enter the value of k = ";        

cin>>k;        

gotoxy(8,18);        

cout<<"Radius of the Ellipse : (rx,ry) :";        

gotoxy(8,19);        

cout<<"ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ";        

gotoxy(12,21);        

cout<<"Enter the radius along x-axis : rx = ";        

cin>>rx;        

gotoxy(12,22);        

cout<<"Enter the radius along y-axis : ry = ";        

cin>>ry;        

initgraph(&driver,&mode,"..Bgi");        

setcolor(15);          

midpoint_ellipse(h,k,rx,ry);        

setcolor(15);          

outtextxy(110,460,"Press <Enter> to continue or any other key to exit.");        

int key=int(getch( ));        

if(key!=13)    

break;     

}         

while(1);         

return 0;      

}   

void midpoint_ellipse(const int h,const int k,const int a,const int b)      

{         

int color=getcolor( );         

float aa=(a*a);         

float bb=(b*b);         

float aa2=(aa*2);         

float bb2=(bb*2);         

float x=0;         

float y=b;         

float fx=0;         

float fy=(aa2*b);         

float p=(int)(bb-(aa*b)+(0.25*aa)+0.5);        

putpixel((h+x),(k+y),color);        

putpixel((h+x),(k-y),color);         

putpixel((h-x),(k-y),color);         

putpixel((h-x),(k+y),color);         

while(fx<fy)     

{        

x++;        

fx+=bb2;        

if(p<0)    

p+=(fx+bb);        

else    

{       

y--;       

fy-=aa2;       

p+=(fx+bb-fy);    

}        

putpixel((h+x),(k+y),color);        

putpixel((h+x),(k-y),color);        

putpixel((h-x),(k-y),color);        

putpixel((h-x),(k+y),color);     }         

p=(int)((bb*(x+0.5)*(x+0.5))+(aa*(y-1)*(y-1))-(aa*bb)+0.5);        

while(y>0)     

{        

y--;        

fy-=aa2;        

if(p>=0)    

p+=(aa-fy);        

else    

{       

x++;       

fx+=bb2;       

p+=(fx+aa-fy);    

}        

putpixel((h+x),(k+y),color);        

putpixel((h+x),(k-y),color);        

putpixel((h-x),(k-y),color);        

putpixel((h-x),(k+y),color);     

}      

}   

void show_screen( )      

{         

restorecrtmode( );         

textmode(C4350);         

cprintf("n********************************************************************************");         

cprintf("************************-                              -************************");         

cprintf("*------------------------ ");         

textbackground(1);         

cprintf(" MidPoint Ellipse Algorithm ");         

textbackground(8);         

cprintf(" ------------------------*");         

cprintf("*-**********************-                              -**********************-*");         

cprintf("*-****************************************************************************-*");         

for(int count=0;count<42;count++)     

cprintf("*-*                                                                          *-*");         

gotoxy(1,46);         

cprintf("*-****************************************************************************-*");         

cprintf("*------------------------------------------------------------------------------*");         

cprintf("********************************************************************************");         

gotoxy(1,2);     

}

--

Don't ever give up.

Even when it seems impossible,

Something will always

pull you through.

The hardest times get even

worse when you lose hope.

As long as you believe you can do it, You can.

But When you give up,

You lose !

I DONT GIVE UP.....!!!

with regards

prem sasi kumar arivukalanjiam