// 3次元空間の広さ
const double  L = 32.0;

//---- Graphics settings.
// properties about the window size.
const int      WIN_WID      =  256;
const int      WIN_HEI      =  256;
const GLfloat  WIN_COL[]    = { 0.0, 0.0, 0.0, 1.0 };

// properties about the scope.
const GLdouble EYE_POS[]    = { 0.0, 2*L, L/2 };
const GLdouble GAZE_POS[]   = { 0.0, 0.0, 0.0 };
const GLdouble UP_DIR[]     = { 0.0, -L, L*4 };
const GLdouble SCOPE_ANG    = 32.0;
const GLdouble SCOPE_NEAR   = L/2;
const GLdouble SCOPE_FAR    = 8*L;

// properties about the light.
      GLfloat  LIGHT_POS[]  = { L, L, 3*L };
const GLfloat  LIGHT_DIF[]  = { 1.0, 1.0, 1.0, 1.0 };
const GLfloat  LIGHT_SPE[]  = { 1.0, 1.0, 1.0, 1.0 };
const GLfloat  LIGHT_AMB[]  = { 0.5, 0.5, 0.5, 1.0 };


/*********** Definition of OpenGL callback functions **********************/

double dthe = 0.0, dphi = 0.0;

//---- Callback function which is called to draw.
void myDisplay(void)
{
  glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

  glPushMatrix();{
    glCallList(1);
  }glPopMatrix();

  glFlush();
  glutSwapBuffers();
}


//---- Mouseの callback
void myMouse( int button, int state, int x, int y )
{
  static int xs=0, ys=0, xe, ye;
  
  if( button == GLUT_LEFT_BUTTON ){
    if( state == GLUT_DOWN ){
      xs = x, ys = y;
    }else if( state == GLUT_UP ){
      xe = x, ye = y;
      dthe = double((ye-ys)/16);
      dphi = double((xe-xs)/16);
      xs = xe, ys = ye;

      if( dthe == 0.0 && dphi == 0.0 ){
	glutIdleFunc( NULL );
      }else{
	glutIdleFunc( myIdle );
      }
    }
  }
}

//---- Callback function which is called by the keyboard actions.
void myNormalKey( int k, int x, int y )
{
  switch( k ){
    case 's'            : {
      char fname[64];
      fprintf( stdout, "Input file name:");
      fflush( stdout );
      fscanf( stdin, "%s", fname );
      fflush( stdin );
      glutSaveWindow(fname);
      break;
    }
  }
  glutPostRedisplay();
}
void mySpecialKey( int k, int x, int y )
{
  switch( k ){
    case GLUT_KEY_ESC   : exit(0);
  }
  glutPostRedisplay();
}

//---- idle時に計算を行うcallback
void myIdle( void )
{
  glRotateL(dthe, 1.0, 0.0, 0.0 );
  glRotateL(dphi, 0.0, 1.0, 0.0 );
  glutPostRedisplay();
}

//---- セットアップを行う関数
void stdSetup( int& argc, char** argv )
{
  glutOpenWindow( argc, argv, WIN_WID, WIN_HEI, WIN_COL );
  glutSetEye( SCOPE_ANG, SCOPE_NEAR, SCOPE_FAR, EYE_POS, GAZE_POS, UP_DIR );
  glutSetLight( LIGHT_POS, LIGHT_AMB, LIGHT_DIF, LIGHT_SPE );
  glutIdleFunc( NULL );
}