Bresenham's circle Drawing Algorithm example problems

Example 1: bresenham circle drawing algorithm

void    EightWaySymmetricPlot(int xc,int yc,int x,int y)  
   {  
    putpixel(x+xc,y+yc,RED);  
    putpixel(x+xc,-y+yc,YELLOW);  
    putpixel(-x+xc,-y+yc,GREEN);  
    putpixel(-x+xc,y+yc,YELLOW);  
    putpixel(y+xc,x+yc,12);  
    putpixel(y+xc,-x+yc,14);  
    putpixel(-y+xc,-x+yc,15);  
    putpixel(-y+xc,x+yc,6);  
   }  
  
    void BresenhamCircle(int xc,int yc,int r)  
   {  
    int x=0,y=r,d=3-(2*r);  
    EightWaySymmetricPlot(xc,yc,x,y);  
  
    while(x<=y)  
     {  
      if(d<=0)  
             {  
        d=d+(4*x)+6;  
      }  
     else  
      {  
        d=d+(4*x)-(4*y)+10;  
        y=y-1;  
      }  
       x=x+1;  
       EightWaySymmetricPlot(xc,yc,x,y);  
      }  
    }

Example 2: bresenham line drawing algorithm code

#include<iostream.h>
#include<graphics.h>
 
void drawline(int x0, int y0, int x1, int y1)
{
    int dx, dy, p, x, y;
 
	dx=x1-x0;
	dy=y1-y0;
 
	x=x0;
	y=y0;
 
	p=2*dy-dx;
 
	while(x<x1)
	{
		if(p>=0)
		{
			putpixel(x,y,7);
			y=y+1;
			p=p+2*dy-2*dx;
		}
		else
		{
			putpixel(x,y,7);
			p=p+2*dy;
		}
		x=x+1;
	}
}
 
int main()
{
	int gdriver=DETECT, gmode, error, x0, y0, x1, y1;
	initgraph(&gdriver, &gmode, "c:\\turboc3\\bgi");
 
	cout<<"Enter co-ordinates of first point: ";
	cin>>x0>>y0;
 
	cout<<"Enter co-ordinates of second point: ";
	cin>>x1>>y1;
	drawline(x0, y0, x1, y1);
 
	return 0;
}