/************************************************************
 * File: subwindow.cc
 * Author: C.Yap
 * Date: Sep 23, 2001.
 * Synopsis:  
 *	OpenGL program for lecture 2
 * 	Illustrates the use of subwindows
 *	
 ************************************************************/

#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()
  
void displayButton(char* label, int state) {
  int len, i;

  glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
  glColor3f(1.0, 1.0, 0.0);

  glPushMatrix();
  glTranslatef(-40, 0, 0);
  glScalef(8.0, 8.0, 1.0);
  if (state)  drawButton();
  else drawPressedButton();
  glScalef(.125, .125, 1.0);
  glTranslatef(20, -5.0, 0.0);
  glScalef(0.1, 0.1, 0.1);
  len = (int) strlen(label);
  for (i = 0; i < len; i++) {
    glutStrokeCharacter(GLUT_STROKE_MONO_ROMAN, label[i]);
  }
  glPopMatrix();

  glFlush();  
  glutSwapBuffers();
}

void buttonDisplay(void)
{
  displayButton(buttonLabel, OnOffFlag);
}

/////////////////////////////////////////////////////////////
// MAIN PROGRAM
/////////////////////////////////////////////////////////////

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

  /////////////////////////////////////////////////////////////
  // initialize main 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
  int mainWin;
  mainWin = glutCreateWindow("My First Window");	// open it

  /////////////////////////////////////////////////////////////
  // initialize subwindows
  /////////////////////////////////////////////////////////////

  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);			// point is 2 pixels wide (default 1)
  glLineWidth(2.0);			// line width 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

  /////////////////////////////////////////////////////////////
  // initialize subwindows
  /////////////////////////////////////////////////////////////
  int button;
  int OnOffFlag = 0; // 0=off, 1=on
  button = glutCreateSubWindow(mainWin, 10, 10, 40, 40); // button size 40x40
  glClearColor(0.0, 0.0, 0.5, 0.0);
  glutDisplayFunc( displayButton ); 
  glutReshapeFunc( reshapeButton ); 
  glutMouseFunc(   mouseButton ); 
  
  // end of subwins definitions
  
  // set the current window back to the top level one
  glutSetWindow(mainWin);

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

  glutDisplayFunc(myDisplay);	   // redraw window event


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

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