/************************************************************
 * File: window.cc
 * Author: C.Yap
 * Date: Sep 23, 2001.
 * Synopsis:  
 *	OpenGL program for lecture 2
 * 	Illustrates the initialization for a display window
 *	in GLUT.
 *	
 ************************************************************/

#include <iostream.h>	// needed for use of cout
#include <math.h>	// needed for math functions exp(x), etc

// #include <windows.h>
#include <GL/glut.h>

/////////////////////////////////////////////////////////////
// constants
/////////////////////////////////////////////////////////////
int screenWidth = 640;
int screenHeight = 640;

/////////////////////////////////////////////////////////////
// callback functions
/////////////////////////////////////////////////////////////

void myDisplay(void)
{
  glClear(GL_COLOR_BUFFER_BIT);	// clear screen
	// Exercise: what would happen if you do not clear screen?
  glColor3f(0.0f, 0.0f, 1.0f);		// pen is blue
  glBegin(GL_LINES);
      glVertex2d(10, 10) ;
      glVertex2d(900, 900) ;
  glEnd();
  glFlush();
}//myDisplay()
  
/////////////////////////////////////////////////////////////
// MAIN PROGRAM
/////////////////////////////////////////////////////////////

void main(int argc, char** argv) 
{

  /////////////////////////////////////////////////////////////
  // initialization and create screen window
  /////////////////////////////////////////////////////////////

  glutInit(&argc, argv);  		// initialize toolkit
  glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); // display mode (single buffer)
  // glutInitWindowSize(screenWidth, screenHeight); // window size
  // glutInitWindowPosition(100, 150);	// position of top right corner
  glutCreateWindow("My First Window");	// open it

  // glClearColor(1.0, 1.0, 1.0, 0.0);	// background is white (default black)
  glColor3f(0.0f, 0.0f, 1.0f);		// pen is blue (default black)
  // glPointSize(2.0);			// dot is 2pixels wide (default 1)
  glMatrixMode(GL_PROJECTION);		// set camera shape
  glLoadIdentity();			// initialize projection matrix
  gluOrtho2D(0.0, (GLdouble)screenWidth,
  	0.0, (GLdouble)screenHeight);	// set matrix for 2D graphics

  /////////////////////////////////////////////////////////////
  // register callback functions
  /////////////////////////////////////////////////////////////

  glutDisplayFunc(myDisplay);	   // redraw window event


  /////////////////////////////////////////////////////////////
  glutMainLoop();	// mandatory final call to glut
  /////////////////////////////////////////////////////////////
}//main

/////////////////////////////////////////////////////////////
// The end
/////////////////////////////////////////////////////////////