// Skeleton program for GLUT applications.

// Link with: opengl32.lib, glu32.lib, glut32.lib.

#include <GL/glut.h>
#include <math.h>
#include <iostream.h>
#include <strstrea.h>
#include <iomanip.h>

// Initial size of graphics window.
const int WIDTH  = 600;
const int HEIGHT = 400;

// Current size of window.
int width  = WIDTH;
int height = HEIGHT;

// Mouse positions, normalized to [0,1].
double xMouse = 0.5;
double yMouse = 0.5;

// Bounds of viewing frustum.
double nearPlane =  5;
double farPlane  = 15;

// Viewing angle.
double fovy = 40.0;

// Variables.
double alpha = 0;                                  // Set by idle function.
double beta = 0;                                   // Set by mouse X.
double distance = - (farPlane - nearPlane) / 2;    // Set by mouse Y.

// This function is called to display the scene.
void display ()
{
 	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();

   // Translate using Y mouse.
   distance = - (yMouse * (farPlane - nearPlane) + nearPlane);
   glTranslatef(0, 0, distance);

   // Rotation from idle function.
   glRotatef(alpha, 0, 1, 0);
   
   // Rotation using X mouse.
   beta = 180.0 * xMouse;
   glRotatef(beta, 1, 0, 0);

   // Draw model axes.
   glBegin(GL_LINES);
      // X axis
      glColor3f(1, 0, 0);
      glVertex3f(0, 0, 0);
      glVertex3f(2, 0, 0);
      // Y axis
      glColor3f(0, 1, 0);
      glVertex3f(0, 0, 0);
      glVertex3f(0, 2, 0);
      // Z axis
      glColor3f(0, 0, 1);
      glVertex3f(0, 0, 0);
      glVertex3f(0, 0, 2);
   glEnd();

   // Draw an object.
   glColor3f(0, 1, 1);
   glutWireSphere(1, 20, 20);

	glutSwapBuffers();
}

// This function is called when there is nothing else to do.
void idle ()
{
   const double STEP = 0.1;
   const double ALL_ROUND = 360;
   alpha += STEP;
   if (alpha > ALL_ROUND)
      alpha -= ALL_ROUND;

   // Display normalized coordinates in title bar.
   const int BUFSIZE = 200;
   static char buffer[BUFSIZE];
   ostrstream s(buffer, BUFSIZE);
   s << 
      resetiosflags(ios::floatfield) << setiosflags(ios::fixed) << 
      setprecision(3) << "Mouse at (" << xMouse << ", " << yMouse << 
      setprecision(0) << ").  Alpha=" << setw(3) << alpha << 
      ".  Beta=" << setw(3) << beta <<
      setprecision(2) << ".  Distance=" << distance <<
      "." << ends;
   glutSetWindowTitle(buffer);

	glutPostRedisplay();
}

void mouseMovement (int mx, int my)
{
   // Normalize mouse coordinates.
   xMouse = double(mx) / double(width);
   yMouse = 1 - double(my) / double(height);

   // Redisplay image.
   glutPostRedisplay();
}

// Respond to window resizing, preserving proportions.
// Parameters give new window size in pixels.
void reshapeMainWindow (int newWidth, int newHeight)
{
   width = newWidth;
   height = newHeight;
	glViewport(0, 0, width, height);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
   gluPerspective(fovy, GLfloat(width) / GLfloat(height), nearPlane, farPlane);
}

// Display help.
void help()
{
   cout << 
      "'h'   display help" << endl <<
      endl;
}

// Respond to graphic character keys.
// Parameters give key code and mouse coordinates.
void graphicKeys (unsigned char key, int x, int y)
{
	switch (key)
	{
   case 'h':
      help();
      break;
	case 27:
		exit(0);
   default:
      cout << key << endl;
	}
}

// Respond to function keys.
// Parameters give key code and mouse coordinates.
void functionKeys (int key, int x, int y)
{
   switch (key)
   {
   case GLUT_KEY_F1:
      cout << "F1" << endl;
      break;
   case GLUT_KEY_UP:
      cout << "Up" << endl;
      break;
   }
}


void main (int argc, char **argv)
{
   // GLUT initialization.
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
	glutInitWindowSize(width, height);
	glutCreateWindow("GLUT Skeleton Program");

   // Register call backs.
	glutDisplayFunc(display);
	glutReshapeFunc(reshapeMainWindow);
	glutKeyboardFunc(graphicKeys);
   glutSpecialFunc(functionKeys);
   glutMotionFunc(mouseMovement);
	glutIdleFunc(idle);

   // OpenGL initialization
   glEnable(GL_DEPTH_TEST);

   // Display help.
	help();

   // Enter GLUT loop.
	glutMainLoop();
}