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#include<windows.h>
#include<iostream>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
#include<GL/gl.h>
#include<GL/glu.h>
#include<GL/glut.h>


const int screenWidth = 640*2;
const int screenHeight = 480*2;
GLdouble A,B,C,D; // values for scaling and shifting

void myInit(void)
{
  glClearColor(1.0, 1.0, 1.0, 0.0);  //background color is white
  glColor3f(0.0f, 0.0f, 0.0f);  //drawing color is black
  glPointSize(4.0); //a dot is 2 by 2 pixels
  glLineWidth(4.0); //a line is 4 times thicker


//initialize view (simple orthographic projection)
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glOrtho(-1.0,1.0,-1.0, 1.0, -1.0, 1.0);

  A = screenWidth/4.0; //Set values for scaling and shifting
  B= 0.0;
  C=D=screenHeight/2.0;

  //set the viewing coordinates
  gluOrtho2D(0.0, 640.0, 0.0, 480.0);
}

void myDisplay(void)
{
  glClear(GL_COLOR_BUFFER_BIT);   //clear the screen
  // glRecti(10,10,150,60); //draw a rectangle with background color


  glPointSize(2.0);


  GLint h = 300, k = 300, x, x2, y, i = 1, a = 150, b = 25;

  x2 = a;

  for(x=1;x<=x2;x++)
    {
      y = b * sqrt(1 - (pow(x,2)/pow(a,2)));

	  glBegin(GL_POINTS);
      {

	glVertex2i(x+h,y+k);
	glVertex2i(-x+h,-y+k);
	glVertex2i(-x+h,y+k);
	glVertex2i(x+h,-y+k);
	}
      glEnd();
	}

  glFlush(); //send all output to display
}


int  main(int argc, char** argv)
{
  glutInit(&argc, argv);  //initialize the toolkit
  glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); //set the display mode
  glutInitWindowSize(640,480);  //set window size
  //set window position on screen
  glutInitWindowPosition(100,150);
  //open the screen window and set the name
  glutCreateWindow("My First Window");

  //register the callback functions
  glutDisplayFunc(myDisplay);

  myInit();
  glutMainLoop();  //go into a perpetual loop

return 1;

}