Mid Point Circle Drawing.c

#include<stdlib.h>
#include<stdio.h>
#include <GL/gl.h>
#include <GL/glut.h>
float xc, yc, r;
void TakeInput()
{
	printf("Value of x1 : ");
	scanf("%f", & xc);
	printf("Value of y1 : ");
	scanf("%f", & yc);
	printf("Enter the radius : ");
	scanf("%f", & r);
}
void display(void)
{
	float p = 1 - r;
	float x = 0;
	float y = r;
	glBegin(GL_POINTS);
	glVertex2f(xc + x, yc + y);
	glVertex2f(xc + y, yc + x);
	glVertex2f(xc + x, yc - y);
	glVertex2f(xc - y, yc - x);
	while (x <= y)
	{
		if (p < 0)
		{
			x = x + 1;
			p = p + 2.0 * x + 1;
		}
		else
		{
			x = x + 1;
			y = y - 1;
			p = p + 2 * (x - y) + 1;
		}
		glVertex2f(xc + x, yc + y);
		glVertex2f(xc + x, yc - y);
		glVertex2f(xc - x, yc + y);
		glVertex2f(xc - x, yc - y);
		glVertex2f(xc + y, yc + x);
		glVertex2f(xc - y, yc + x);
		glVertex2f(xc + y, yc - x);
		glVertex2f(xc - y, yc - x);
	}
	glEnd();
	glFlush();
}
int main(int argc, char ** argv)
{
	TakeInput();
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
	glutInitWindowSize(500, 500);
	glutInitWindowPosition(100, 150);
	glutCreateWindow("Circle Drawing Using OpenGL");
	glClearColor(0, 0, 0, 0);
	glClear(GL_COLOR_BUFFER_BIT);
	gluOrtho2D(-250, 250, -250, 250);
	glMatrixMode(GL_PROJECTION);
	glViewport(0, 0, 500, 500);
	glutDisplayFunc(display);
	glutMainLoop();
	return 0;
}