/************************************************************
 * File: simple1.cc
 * Author: C.Yap
 * Date: Sep 7, 2001.
 * Synopsis:  
 * 	Elaboration of simple.cc
 *	--Puts a multicolor frame around window
 *	
 ************************************************************/

#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
/////////////////////////////////////////////////////////////
  const int screenWidth = 640;
  const int screenHeight = 480;

/////////////////////////////////////////////////////////////
// Initialization
/////////////////////////////////////////////////////////////

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

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

void myDisplay(void)
{
  glClear(GL_COLOR_BUFFER_BIT);	// clear screen

  // DRAW A COLORED FRAME AROUND WINDOW
  glLineWidth(4.0);
  glBegin(GL_LINE_LOOP);
    glColor3f(0.1, 0.9, 0.1);  // green
    glVertex2d(screenWidth-10, screenHeight-10);
    glVertex2d(screenWidth-10, 10);
    glColor3f(0.9, 0.1, 0.1);  // red
    glVertex2d(10, 10);
    glColor3f(0.0, 0.0, 0.0);  // black
    glVertex2d(10, screenHeight-10);
    glColor3f(0.9, 0.9, 0.1);  // yellow
  glEnd();

  // PLOT FUNCTION: y = exp(-x) * cos (8 * pi * x) 
  // 		-- 8*pi gives us 4 full circles.
  glBegin(GL_POINTS);
    glColor3f(0.0f, 0.0f, 1.0f);		// pen is blue
    for (GLdouble x = 10; x < screenWidth-10; x += 1) {
      GLdouble y = exp(-3*x/screenWidth) * cos(16 * 3.14159265 * x/screenWidth);
      y = y*(screenHeight/2) + (screenHeight/2) ;
      glVertex2d(x, y) ;
    }//for
  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

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

  glutDisplayFunc(myDisplay);	   // redraw window event
  // glutReshapeFunc(myReshape);   // reshape window event
  // glutMouseFunc(myMouse);	   // mouse button event
  // glutKeyboardFunc(myKeyboard); // keyboard event

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

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