/////////////////////////////////////////////////////         
// windows.cpp
//
// This program creates two top-level OpenGL windows.
//
// Sumanta Guha.
///////////////////////////////////////////////////// 

#include <cmath>
#include <iostream>

#ifdef __APPLE__
#  include <GLUT/glut.h>
#else
#  include <GL/glut.h>
#endif

#define PI 3.14159265

using namespace std;

// Globals.
static int id1, id2; // Window identifiers.

// Drawing routine for first window.
void drawScene1(void)
{
   // Choose window.
   glutSetWindow(id1);

   glClear(GL_COLOR_BUFFER_BIT);

   // A red square.
   glColor3f(1.0, 0.0, 0.0);	
   glBegin(GL_POLYGON);
      glVertex3f(10.0, 10.0, 0.0);
      glVertex3f(40.0, 10.0, 0.0);
      glVertex3f(40.0, 40.0, 0.0);
      glVertex3f(10.0, 40.0, 0.0);
   glEnd();

   glFlush();
}

// Drawing routine for second window.
void drawScene2(void)
{
   // Choose window.
   glutSetWindow(id2);

   glClear(GL_COLOR_BUFFER_BIT);

   // A blue circle.
   glColor3f(0.0, 0.0, 1.0);
   float angle;
   int i;
   glBegin(GL_LINE_LOOP);
   for(i = 0; i < 30; ++i)
   {
      angle = 2 * PI * i / 30;
      glVertex2f(50.0 + cos(angle) * 40.0, 50.0 + sin(angle) * 40.0);
   }
   glEnd();

   glFlush();
}

// Initialization routine for first window.
void setup1(void) 
{
   // Black background.
   glClearColor(1.0, 1.0, 1.0, 0.0);
}

// Initialization routine for second window.
void setup2(void) 
{
   // Green background.
   glClearColor(1.0, 1.0, 1.0, 0.0);
}

// Reshape routine for first window.
void resize1(int w, int h)
{
   glViewport(0, 0, (GLsizei) w, (GLsizei) h);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();

   // Non-square aspect ratio squashes the square.
   glOrtho(0.0, 50.0, 0.0, 100.0, -1.0, 1.0);

   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
}

// Reshape routine for second window.
void resize2(int w, int h)
{
   glViewport(0, 0, (GLsizei)w, (GLsizei)h);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   glOrtho(0.0, 100.0, 0.0, 100.0, -1.0, 1.0);
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
}

// Keyboard input processing routine shared by both windows.
void keyInput(unsigned char key, int x, int y)
{
   switch(key) 
   {
      case 27:
         exit(0);
         break;
      default:
         break;
   }
}

// Main routine.
int main(int argc, char **argv) 
{
   glutInit(&argc, argv);
   glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
   
   // First top-level window definition.
   glutInitWindowSize(250, 500); 
   glutInitWindowPosition(100, 100);

   // Create the first window and return id.
   id1 = glutCreateWindow("windows.cpp - window 1"); 

   // Initialization, display, and other routines of the first window. 
   setup1();
   glutDisplayFunc(drawScene1); 
   glutReshapeFunc(resize1);
   glutKeyboardFunc(keyInput); // Routine is shared by both windows.
   
   // Second top-level window definition.
   glutInitWindowSize(250, 500); 
   glutInitWindowPosition(400, 100);
   
   // Create the second window and return id.
   id2 = glutCreateWindow("windows.cpp - window 2"); 

   // Initialization, display, and other routines of the second window. 
   setup2(); 
   glutDisplayFunc(drawScene2); 
   glutReshapeFunc(resize2);
   glutKeyboardFunc(keyInput); // Routine is shared by both windows.

   glutMainLoop();

   return 0;   
}