flag.CPP

#include<iostream.h>
#include<conio.h>
#include<stdlib.h>
#include<graphics.h>
#include<dos.h>
#include<math.h>
void circ_bre(int x,int y,int rad);
void display(int,int,int,int);
void bresenham(int x1,int y1,int x2, int y2);
int sign (float arg);

void main()
{
	int gd = DETECT, gm, x,y,r;
	initgraph(&gd,&gm,"c:\\tc\\bgi");
	cleardevice();
	
	circ_bre(225,200,30);
	

	bresenham(120,130,330,130);
	bresenham(120,130,120,270);
	bresenham(120,270,330,270);
	bresenham(330,130,330,270);
	bresenham(225,150,150,200);
	bresenham(150,200,225,250);
	bresenham(225,150,300,200);
	bresenham(300,200,225,250);
	
	
	

	getch();
	closegraph();
}
void circ_bre(int x,int y,int rad)
{
	float dp;	    //initialising the descision parameter.
	int x1,y1;
	x1 = 0;       	   //initialisng the X,Y cordinates.
	y1 = rad;
	dp = 3 - 2*rad;
	while(x1<=y1)
	{
		if(dp<=0)
			dp += (4 * x1) + 6;
		else
		{
			dp += 4*(x1-y1)+10;
			y1--;
		}
		x1++;
		display(x1,y1,x,y);
	}
}
void display (int x1,int y1,int x,int y)
{
	putpixel(x1+x,y1+y,WHITE);	//plotting the pixels.
	putpixel(x1+x,y-y1,WHITE);
	putpixel(x-x1,y1+y,WHITE);
	putpixel(x-x1,y-y1,WHITE);
	putpixel(x+y1,y+x1,WHITE);
	putpixel(x+y1,y-x1,WHITE);
	putpixel(x-y1,y+x1,WHITE);
	putpixel(x-y1,y-x1,WHITE);
}
void bresenham(int x1,int y1,int x2,int y2)
{
	int s1,s2,exchange,y,x,i;
	float dx,dy,g,temp;
	dx = abs(x2 - x1);
	dy = abs(y2 - y1);
	x = x1;
	y = y1;
	s1 = sign(x2-x1);
	s2 = sign(y2-y1);	/* interchange dx & dy depending on the slope of 																								the line */
	if(dy>dx)
	{
		temp = dx;
		dx = dy;
		dy = temp;
		exchange  = 1;
	}
	else
		exchange = 0;
	g = 2 * dy - dx;
	i = 1;
	while(i<=dx)
	{
		putpixel(x,y,WHITE);
		delay(10);
		while(g>=0)
		{
			if(exchange ==1)
				x = x + s1;
			else
				y = y + s2;
			g = g - 2 * dx;
		}
		if(exchange==1)
			y = y + s2;
		else
			x = x + s1;
		g = g + 2 * dy;
		i++;
	}
}
int sign(float arg)
	{
	if (arg<0)
		return -1;
		else if(arg==0)
			return 0;
				 else return 1;
	}