#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <GL/glut.h>


int   cube_exploded = 0;
float angle = 0.0; // camera rotation angle


//
// Light sources
GLfloat  light0Amb[4] =  { 1.0, 0.6, 0.2, 1.0 };
GLfloat  light0Dif[4] =  { 1.0, 0.6, 0.2, 1.0 };   
GLfloat  light0Spec[4] = { 0.0, 0.0, 0.0, 1.0 };   
GLfloat  light0Pos[4] =  { 0.0, 0.0, 0.0, 1.0 };
GLfloat  light1Amb[4] =  { 0.0, 0.0, 0.0, 1.0 };
GLfloat  light1Dif[4] =  { 1.0, 1.0, 1.0, 1.0 };   
GLfloat  light1Spec[4] = { 1.0, 1.0, 1.0, 1.0 };   
GLfloat  light1Pos[4] =  { 0.0, 5.0, 5.0, 0.0 };




void display (void);
void keyboard (unsigned char, int, int);
void reshape (int, int);
void idle (void);
void explode_cube (void);





void display (void)
{
  int i;

  glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  glLoadIdentity ();
//
// Place the camera
  glTranslatef (0.0, 0.0, -10.0);
  glRotatef (angle, 0.0, 1.0, 0.0);
//
// If no explosion, draw cube
  if (!cube_exploded)
  {
    glEnable (GL_LIGHTING);
    glDisable (GL_LIGHT0);
    glEnable (GL_DEPTH_TEST);
    glutSolidCube (1.0);
  }
  glutSwapBuffers ();
}





void keyboard (unsigned char key, int x, int y)
{
  switch (key)
  {
    case ' ':
      explode_cube();
      exit (0);
    break;
    case 27:
      exit (0);
    break;
  }
}





void reshape (int w, int h)
{
  glViewport (0.0, 0.0, (GLfloat) w, (GLfloat) h);
  glMatrixMode (GL_PROJECTION);
  glLoadIdentity ();
  gluPerspective (45.0, (GLfloat) w / (GLfloat) h, 0.1, 100.0);
  glMatrixMode (GL_MODELVIEW);
}





void idle (void)
{
  angle += 0.3;  /* Always continue to rotate the camera */
  glutPostRedisplay ();
}









void explode_cube(void)
{
  cube_exploded = 1;
  printf ("BOOM!\n");
}




int main (int argc, char *argv[])
{
  glutInit (&argc, argv);
  glutInitWindowPosition (0, 0);
  glutInitWindowSize (1280, 1024);
  glutInitDisplayMode (GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE);
  glutCreateWindow ("Particle explosion");
  glutKeyboardFunc (keyboard);
  glutIdleFunc (idle);
  glutDisplayFunc (display);
  glutReshapeFunc (reshape);
  glEnable (GL_LIGHT0);
  glEnable (GL_LIGHT1);
  glLightfv (GL_LIGHT0, GL_AMBIENT, light0Amb);
  glLightfv (GL_LIGHT0, GL_DIFFUSE, light0Dif);
  glLightfv (GL_LIGHT0, GL_SPECULAR, light0Spec);
  glLightfv (GL_LIGHT0, GL_POSITION, light0Pos);
  glLightfv (GL_LIGHT1, GL_AMBIENT, light1Amb);
  glLightfv (GL_LIGHT1, GL_DIFFUSE, light1Dif);
  glLightfv (GL_LIGHT1, GL_SPECULAR, light1Spec);
  glLightfv (GL_LIGHT1, GL_POSITION, light1Pos);
  glLightModelf (GL_LIGHT_MODEL_TWO_SIDE, GL_TRUE);
  glEnable (GL_NORMALIZE);
  glutMainLoop ();
  return 0;
}