Mid Point Ellipse Drawing Algorithm

This program is for implementing Mid Point Ellipse Drawing Algorithm. This is a part of Mumbai University MCA Colleges Computer Graphics CG MCA Sem 2

#include<stdio.h>

#include<conio.h>

#include<math.h>

#include<graphics.h>

void plot(int xc,int yc,int x,int y)

{

            putpixel(x+xc,y+yc,1);

            putpixel(x+xc,-y+yc,1);

            putpixel(-x+xc,y+yc,1);

            putpixel(-x+xc,-y+yc,1);

}

void myellipse(int xc,int yc,int rx,int ry)

{

            long rx2,ry2,px,py,tworx2,twory2,p;

            float x,y;

            x=0;

            y=ry;

            rx2=rx*rx;

            ry2=ry*ry;

            tworx2=2*rx2;

            twory2=2*ry2;

            px=0;

            py=tworx2*y;

//Printing the initial point

            plot(xc,yc,x,y);

            p=(int)(ry2-(rx2*ry)+(0.25*rx2));

            while(px<py)

            {

                        x++;

                        px+=twory2;

                        if(p<0)

                                    p+=px+ry2;

                        else

                        {

                                    y=y-1;

                                    py-=tworx2;

                                    p+=ry2+px-py;

                        }

                        plot(xc,yc,x,y);

            }

            p=(int)((ry2*(x+0.5)*(x+0.5)+rx2*(y-1)*(y-1)-rx2*ry2));

            while(y>0)

            {

                        y--;

                        py-=tworx2;

                        if(p>0)

                                    p+=rx2-py;

                        else

                        {

                                    x++;

                                    px+=twory2;

                                    p+=rx2-py+px;

                        }

                        plot(xc,yc,x,y);

            }

}

void main()

{

            int gd,gm;

            int xc,yc,rx,ry;

            clrscr();

            gd=DETECT;

            detectgraph(&gd,&gm);

            printf("Enter values of centre of ellipse\n");

            scanf("%d%d",&xc,&yc);

            printf("Enter the x radius and y radius\n");

            scanf("%d%d",&rx,&ry);

            initgraph(&gd,&gm,"c:\\tc\\bgi");

            myellipse(xc,yc,rx,ry);

            getch();

}



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