/*
 * General settings assignment method
 */
void FGAPIENTRY glutSetOption( GLenum eWhat, int value )
{
    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutSetOption" );

    /*
     * XXX In chronological code add order.  (WHY in that order?)
     */
    switch( eWhat )
    {
    case GLUT_INIT_WINDOW_X:
        fgState.Position.X = (GLint)value;
        break;

    case GLUT_INIT_WINDOW_Y:
        fgState.Position.Y = (GLint)value;
        break;

    case GLUT_INIT_WINDOW_WIDTH:
        fgState.Size.X = (GLint)value;
        break;

    case GLUT_INIT_WINDOW_HEIGHT:
        fgState.Size.Y = (GLint)value;
        break;

    case GLUT_INIT_DISPLAY_MODE:
        fgState.DisplayMode = (unsigned int)value;
        break;

    case GLUT_ACTION_ON_WINDOW_CLOSE:
        fgState.ActionOnWindowClose = value;
        break;

    case GLUT_RENDERING_CONTEXT:
        fgState.UseCurrentContext =
            ( value == GLUT_USE_CURRENT_CONTEXT ) ? GL_TRUE : GL_FALSE;
        break;

    case GLUT_DIRECT_RENDERING:
        fgState.DirectContext = value;
        break;

    case GLUT_WINDOW_CURSOR:
        if( fgStructure.CurrentWindow != NULL )
            fgStructure.CurrentWindow->State.Cursor = value;
        break;

    case GLUT_AUX:
      fgState.AuxiliaryBufferNumber = value;
      break;

    case GLUT_MULTISAMPLE:
      fgState.SampleNumber = value;
      break;

    case GLUT_SKIP_STALE_MOTION_EVENTS:
      fgState.SkipStaleMotion = value;
      break;

    default:
        fgWarning( "glutSetOption(): missing enum handle %d", eWhat );
        break;
    }
}

/*
 * Draws a solid cone
 */
void FGAPIENTRY glutSolidCone( GLdouble base, GLdouble height, GLint slices, GLint stacks )
{
    int i,j;

    /* Step in z and radius as stacks are drawn. */

    double z0,z1;
    double r0,r1;

    const double zStep = height / ( ( stacks > 0 ) ? stacks : 1 );
    const double rStep = base / ( ( stacks > 0 ) ? stacks : 1 );

    /* Scaling factors for vertex normals */

    const double cosn = ( height / sqrt ( height * height + base * base ));
    const double sinn = ( base   / sqrt ( height * height + base * base ));

    /* Pre-computed circle */

    double *sint,*cost;

    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutSolidCone" );

    fghCircleTable(&sint,&cost,-slices);

    /* Cover the circular base with a triangle fan... */

    z0 = 0.0;
    z1 = zStep;

    r0 = base;
    r1 = r0 - rStep;

    glBegin(GL_TRIANGLE_FAN);

        glNormal3d(0.0,0.0,-1.0);
        glVertex3d(0.0,0.0, z0 );

        for (j=0; j<=slices; j++)
            glVertex3d(cost[j]*r0, sint[j]*r0, z0);

    glEnd();

    /* Cover each stack with a quad strip, except the top stack */

    for( i=0; i<stacks-1; i++ )
    {
        glBegin(GL_QUAD_STRIP);

            for(j=0; j<=slices; j++)
            {
                glNormal3d(cost[j]*sinn, sint[j]*sinn, cosn);
                glVertex3d(cost[j]*r0,   sint[j]*r0,   z0  );
                glVertex3d(cost[j]*r1,   sint[j]*r1,   z1  );
            }

            z0 = z1; z1 += zStep;
            r0 = r1; r1 -= rStep;

        glEnd();
    }

    /* The top stack is covered with individual triangles */

    glBegin(GL_TRIANGLES);

        glNormal3d(cost[0]*sinn, sint[0]*sinn, cosn);

        for (j=0; j<slices; j++)
        {
            glVertex3d(cost[j+0]*r0,   sint[j+0]*r0,   z0    );
            glVertex3d(0,              0,              height);
            glNormal3d(cost[j+1]*sinn, sint[j+1]*sinn, cosn  );
            glVertex3d(cost[j+1]*r0,   sint[j+1]*r0,   z0    );
        }

    glEnd();

    /* Release sin and cos tables */

    free(sint);
    free(cost);
}

/*
 * Draws a wire torus
 */
void FGAPIENTRY glutWireTorus( GLdouble dInnerRadius, GLdouble dOuterRadius, GLint nSides, GLint nRings )
{
  double  iradius = dInnerRadius, oradius = dOuterRadius, phi, psi, dpsi, dphi;
  double *vertex, *normal;
  int    i, j;
  double spsi, cpsi, sphi, cphi ;

  FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutWireTorus" );

  if ( nSides < 1 ) nSides = 1;
  if ( nRings < 1 ) nRings = 1;

  /* Allocate the vertices array */
  vertex = (double *)calloc( sizeof(double), 3 * nSides * nRings );
  normal = (double *)calloc( sizeof(double), 3 * nSides * nRings );

  glPushMatrix();

  dpsi =  2.0 * M_PI / (double)nRings ;
  dphi = -2.0 * M_PI / (double)nSides ;
  psi  = 0.0;

  for( j=0; j<nRings; j++ )
  {
    cpsi = cos ( psi ) ;
    spsi = sin ( psi ) ;
    phi = 0.0;

    for( i=0; i<nSides; i++ )
    {
      int offset = 3 * ( j * nSides + i ) ;
      cphi = cos ( phi ) ;
      sphi = sin ( phi ) ;
      *(vertex + offset + 0) = cpsi * ( oradius + cphi * iradius ) ;
      *(vertex + offset + 1) = spsi * ( oradius + cphi * iradius ) ;
      *(vertex + offset + 2) =                    sphi * iradius  ;
      *(normal + offset + 0) = cpsi * cphi ;
      *(normal + offset + 1) = spsi * cphi ;
      *(normal + offset + 2) =        sphi ;
      phi += dphi;
    }

    psi += dpsi;
  }

  for( i=0; i<nSides; i++ )
  {
    glBegin( GL_LINE_LOOP );

    for( j=0; j<nRings; j++ )
    {
      int offset = 3 * ( j * nSides + i ) ;
      glNormal3dv( normal + offset );
      glVertex3dv( vertex + offset );
    }

    glEnd();
  }

  for( j=0; j<nRings; j++ )
  {
    glBegin(GL_LINE_LOOP);

    for( i=0; i<nSides; i++ )
    {
      int offset = 3 * ( j * nSides + i ) ;
      glNormal3dv( normal + offset );
      glVertex3dv( vertex + offset );
    }

    glEnd();
  }

  free ( vertex ) ;
  free ( normal ) ;
  glPopMatrix();
}

void FGAPIENTRY glutSetMenuData(void* data)
{
    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutSetMenuData" );
    fgStructure.CurrentMenu->UserData=data;
}

/*
 * Draws a solid sphere
 */
void FGAPIENTRY glutSolidSphere(GLdouble radius, GLint slices, GLint stacks)
{
    int i,j;

    /* Adjust z and radius as stacks are drawn. */

    double z0,z1;
    double r0,r1;

    /* Pre-computed circle */

    double *sint1,*cost1;
    double *sint2,*cost2;

    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutSolidSphere" );

    fghCircleTable(&sint1,&cost1,-slices);
    fghCircleTable(&sint2,&cost2,stacks*2);

    /* The top stack is covered with a triangle fan */

    z0 = 1.0;
    z1 = cost2[(stacks>0)?1:0];
    r0 = 0.0;
    r1 = sint2[(stacks>0)?1:0];

    glBegin(GL_TRIANGLE_FAN);

        glNormal3d(0,0,1);
        glVertex3d(0,0,radius);

        for (j=slices; j>=0; j--)
        {
            glNormal3d(cost1[j]*r1,        sint1[j]*r1,        z1       );
            glVertex3d(cost1[j]*r1*radius, sint1[j]*r1*radius, z1*radius);
        }

    glEnd();

    /* Cover each stack with a quad strip, except the top and bottom stacks */

    for( i=1; i<stacks-1; i++ )
    {
        z0 = z1; z1 = cost2[i+1];
        r0 = r1; r1 = sint2[i+1];

        glBegin(GL_QUAD_STRIP);

            for(j=0; j<=slices; j++)
            {
                glNormal3d(cost1[j]*r1,        sint1[j]*r1,        z1       );
                glVertex3d(cost1[j]*r1*radius, sint1[j]*r1*radius, z1*radius);
                glNormal3d(cost1[j]*r0,        sint1[j]*r0,        z0       );
                glVertex3d(cost1[j]*r0*radius, sint1[j]*r0*radius, z0*radius);
            }

        glEnd();
    }

    /* The bottom stack is covered with a triangle fan */

    z0 = z1;
    r0 = r1;

    glBegin(GL_TRIANGLE_FAN);

        glNormal3d(0,0,-1);
        glVertex3d(0,0,-radius);

        for (j=0; j<=slices; j++)
        {
            glNormal3d(cost1[j]*r0,        sint1[j]*r0,        z0       );
            glVertex3d(cost1[j]*r0*radius, sint1[j]*r0*radius, z0*radius);
        }

    glEnd();

    /* Release sin and cos tables */

    free(sint1);
    free(cost1);
    free(sint2);
    free(cost2);
}

/*
 * Returns various device information.
 */
int FGAPIENTRY glutDeviceGet( GLenum eWhat )
{
    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutDeviceGet" );

    /* XXX WARNING: we are mostly lying in this function. */
    switch( eWhat )
    {
    case GLUT_HAS_KEYBOARD:
        /*
         * We always have a keyboard present on PC machines...
         *
         * XXX I think that some of my PCs will boot without a keyboard.
         * XXX Also, who says that we are running on a PC?  UNIX/X11
         * XXX is much more generic, and X11 can go over a network.
         * XXX Though in actuality, we can probably assume BOTH a
         * XXX mouse and keyboard for most/all of our users.
         */
        return TRUE ;

#if TARGET_HOST_UNIX_X11

    case GLUT_HAS_MOUSE:
        return TRUE ;

    case GLUT_NUM_MOUSE_BUTTONS:
        /*
         * Return the number of mouse buttons available. This is a big guess.
         *
         * XXX We can probe /var/run/dmesg.boot which is world-readable.
         * XXX This would be somewhat system-dependant, but is doable.
         * XXX E.g., on NetBSD, my USB mouse registers:
         * XXX   ums0 at uhidev0: 3 buttons and Z dir.
         * XXX We can also probe /var/log/XFree86\..*\.log to get
         * XXX lines such as:
         * XXX   (**) Option "Buttons" "5"
         * XXX   (**) Option "ZAxisMapping" "4 5"
         * XXX   (**) Mouse0: ZAxisMapping: buttons 4 and 5
         * XXX   (**) Mouse0: Buttons: 5
         * XXX ...which tells us even more, and is a bit less
         * XXX system-dependant.  (Other than MS-WINDOWS, all
         * XXX target hosts with actual users are probably running
         * XXX XFree86...)  It is at least worth taking a look at
         * XXX this file.
         */
        return 3 ;

#elif TARGET_HOST_WIN32 || TARGET_HOST_WINCE

    case GLUT_HAS_MOUSE:
        /*
         * The Windows can be booted without a mouse.
         * It would be nice to have this reported.
         */
        return GetSystemMetrics( SM_MOUSEPRESENT );

    case GLUT_NUM_MOUSE_BUTTONS:
        /* We are much more fortunate under Win32 about this... */
#if TARGET_HOST_WINCE
        return 1;
#else
        return GetSystemMetrics( SM_CMOUSEBUTTONS );
#endif /* TARGET_HOST_WINCE */

#endif

    case GLUT_HAS_JOYSTICK:
        return fgJoystickDetect ();

    case GLUT_OWNS_JOYSTICK:
        return fgState.JoysticksInitialised;

    case GLUT_JOYSTICK_POLL_RATE:
        return fgStructure.CurrentWindow ? fgStructure.CurrentWindow->State.JoystickPollRate : 0;

    /* XXX The following two are only for Joystick 0 but this is an improvement */
    case GLUT_JOYSTICK_BUTTONS:
        return glutJoystickGetNumButtons ( 0 );

    case GLUT_JOYSTICK_AXES:
        return glutJoystickGetNumAxes ( 0 );

    case GLUT_HAS_SPACEBALL:
    case GLUT_HAS_DIAL_AND_BUTTON_BOX:
    case GLUT_HAS_TABLET:
        return FALSE;

    case GLUT_NUM_SPACEBALL_BUTTONS:
    case GLUT_NUM_BUTTON_BOX_BUTTONS:
    case GLUT_NUM_DIALS:
    case GLUT_NUM_TABLET_BUTTONS:
        return 0;

    case GLUT_DEVICE_IGNORE_KEY_REPEAT:
        return fgStructure.CurrentWindow ? fgStructure.CurrentWindow->State.IgnoreKeyRepeat : 0;

    case GLUT_DEVICE_KEY_REPEAT:
        return fgState.KeyRepeat;
//.........这里部分代码省略.........

/*
 * Enters the game mode
 */
int FGAPIENTRY glutEnterGameMode( void )
{
    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutEnterGameMode" );

    if( fgStructure.GameModeWindow )
        fgAddToWindowDestroyList( fgStructure.GameModeWindow );
    else
        fghRememberState( );

    if( ! fghChangeDisplayMode( GL_FALSE ) )
    {
        fgWarning( "failed to change screen settings" );
        return 0;
    }

    fgStructure.GameModeWindow = fgCreateWindow(
        NULL, "FREEGLUT", GL_TRUE, 0, 0,
        GL_TRUE, fgState.GameModeSize.X, fgState.GameModeSize.Y,
        GL_TRUE, GL_FALSE
    );

    fgStructure.GameModeWindow->State.Width  = fgState.GameModeSize.X;
    fgStructure.GameModeWindow->State.Height = fgState.GameModeSize.Y;
    fgStructure.GameModeWindow->State.NeedToResize = GL_TRUE;

#if TARGET_HOST_POSIX_X11

    /*
     * Sync needed to avoid a real race, the Xserver must have really created
     * the window before we can grab the pointer into it:
     */
    XSync( fgDisplay.Display, False );
    /*
     * Grab the pointer to confine it into the window after the calls to
     * XWrapPointer() which ensure that the pointer really enters the window.
     *
     * We also need to wait here until XGrabPointer() returns GrabSuccess,
     * otherwise the new window is not viewable yet and if the next function
     * (XSetInputFocus) is called with a not yet viewable window, it will exit
     * the application which we have to aviod, so wait until it's viewable:
     */
    while( GrabSuccess != XGrabPointer(
               fgDisplay.Display, fgStructure.GameModeWindow->Window.Handle,
               TRUE,
               ButtonPressMask | ButtonReleaseMask | ButtonMotionMask
               | PointerMotionMask,
               GrabModeAsync, GrabModeAsync,
               fgStructure.GameModeWindow->Window.Handle, None, CurrentTime) )
        usleep( 100 );
    /*
     * Change input focus to the new window. This will exit the application
     * if the new window is not viewable yet, see the XGrabPointer loop above.
     */
    XSetInputFocus(
        fgDisplay.Display,
        fgStructure.GameModeWindow->Window.Handle,
        RevertToNone,
        CurrentTime
    );

    /* Move the Pointer to the middle of the fullscreen window */
    XWarpPointer(
        fgDisplay.Display,
        None,
        fgDisplay.RootWindow,
        0, 0, 0, 0,
        fgState.GameModeSize.X/2, fgState.GameModeSize.Y/2
    );

#   ifdef HAVE_X11_EXTENSIONS_XF86VMODE_H

    if( fgDisplay.DisplayModeValid )
    {
        int x, y;
        Window child;

        /* Change to viewport to the window topleft edge: */
        if( !XF86VidModeSetViewPort( fgDisplay.Display, fgDisplay.Screen, 0, 0 ) )
            fgWarning( "XF86VidModeSetViewPort failed" );

        /*
         * Final window repositioning: It could be avoided using an undecorated
         * window using override_redirect, but this * would possily require
         * more changes and investigation.
         */

        /* Get the current postion of the drawable area on screen */
        XTranslateCoordinates(
            fgDisplay.Display,
            fgStructure.CurrentWindow->Window.Handle,
            fgDisplay.RootWindow,
            0, 0, &x, &y,
            &child
        );

        /* Move the decorataions out of the topleft corner of the display */
        XMoveWindow( fgDisplay.Display, fgStructure.CurrentWindow->Window.Handle,
//.........这里部分代码省略.........

/* A. Donev: Destruction callback for menus */
void FGAPIENTRY glutMenuDestroyFunc( void (* callback)( void ) )
{
    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutMenuDestroyFunc" );
    if( fgStructure.CurrentMenu )
        fgStructure.CurrentMenu->Destroy = callback;
}

/*
 * Sets the global menu status callback for the current window
 */
void FGAPIENTRY glutMenuStatusFunc( void (* callback)( int, int, int ) )
{
    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutMenuStatusFunc" );
    fgState.MenuStatusCallback = callback;
}

/*
 * Window destruction callbacks
 */
void FGAPIENTRY glutCloseFunc( void (* callback)( void ) )
{
    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutCloseFunc" );
    SET_CALLBACK( Destroy );
}

void FGAPIENTRY glutWMCloseFunc( void (* callback)( void ) )
{
    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutWMCloseFunc" );
    glutCloseFunc( callback );
}

/*
 * Window mouse entry/leave callback
 */
void FGAPIENTRY glutEntryFunc( void (* callback)( int ) )
{
    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutEntryFunc" );
    SET_CALLBACK( Entry );
}

/*
 * Sets the mouse wheel callback for the current window
 */
void FGAPIENTRY glutMouseWheelFunc( void (* callback)( int, int, int, int ) )
{
    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutMouseWheelFunc" );
    SET_CALLBACK( MouseWheel );
}

int * FGAPIENTRY glutGetModeValues(GLenum eWhat, int * size)
{
  int * array;

#if TARGET_HOST_POSIX_X11
  int attributes[9];
  GLXFBConfig * fbconfigArray;  /*  Array of FBConfigs  */
  int fbconfigArraySize;        /*  Number of FBConfigs in the array  */
  int attribute_name = 0;
#endif

  FREEGLUT_EXIT_IF_NOT_INITIALISED("glutGetModeValues");

  array = NULL;
  *size = 0;

  switch (eWhat)
    {
#if TARGET_HOST_POSIX_X11
    case GLUT_AUX:
    case GLUT_MULTISAMPLE:

      attributes[0] = GLX_BUFFER_SIZE;
      attributes[1] = GLX_DONT_CARE;

      switch (eWhat)
        {
        case GLUT_AUX:
          /*
            FBConfigs are now sorted by increasing number of auxiliary
            buffers.  We want at least one buffer.
          */
          attributes[2] = GLX_AUX_BUFFERS;
          attributes[3] = 1;
          attributes[4] = None;

          attribute_name = GLX_AUX_BUFFERS;

          break;


        case GLUT_MULTISAMPLE:
          attributes[2] = GLX_AUX_BUFFERS;
          attributes[3] = GLX_DONT_CARE;
          attributes[4] = GLX_SAMPLE_BUFFERS;
          attributes[5] = 1;
          /*
            FBConfigs are now sorted by increasing number of samples per
            pixel.  We want at least one sample.
          */
          attributes[6] = GLX_SAMPLES;
          attributes[7] = 1;
          attributes[8] = None;

          attribute_name = GLX_SAMPLES;

          break;
        }

      fbconfigArray = glXChooseFBConfig(fgDisplay.Display,
                                        fgDisplay.Screen,
                                        attributes,
                                        &fbconfigArraySize);

      if (fbconfigArray != NULL)
        {
          int * temp_array;
          int previous_value;
          int i;

          temp_array = malloc(sizeof(int) * fbconfigArraySize);
          previous_value = 0;

          for (i = 0; i < fbconfigArraySize; i++)
            {
              int value;

              glXGetFBConfigAttrib(fgDisplay.Display,
                                   fbconfigArray[i],
                                   attribute_name,
                                   &value);
              if (value > previous_value)
                {
                  temp_array[*size] = value;
                  previous_value = value;
                  (*size)++;
                }
            }

          array = malloc(sizeof(int) * (*size));
          for (i = 0; i < *size; i++)
            {
              array[i] = temp_array[i];
            }

          free(temp_array);
          XFree(fbconfigArray);
        }

      break;
//.........这里部分代码省略.........

/*
 * Sets the global idle callback
 */
void FGAPIENTRY glutIdleFunc( void (* callback)( void ) )
{
    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutIdleFunc" );
    fgState.IdleCallback = callback;
}

/*
 * Sets the overlay display callback for the current window
 */
void FGAPIENTRY glutOverlayDisplayFunc( void (* callback)( void ) )
{
    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutOverlayDisplayFunc" );
    SET_CALLBACK( OverlayDisplay );
}

/*
 * General settings query method
 */
int FGAPIENTRY glutGet( GLenum eWhat )
{
#if TARGET_HOST_WIN32 || TARGET_HOST_WINCE
    int returnValue ;
    GLboolean boolValue ;
#endif

    switch (eWhat)
    {
    case GLUT_INIT_STATE:
        return fgState.Initialised;

    case GLUT_ELAPSED_TIME:
        return fgElapsedTime();
    }

    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutGet" );

    /* XXX In chronological code add order.  (WHY in that order?) */
    switch( eWhat )
    {
    /* Following values are stored in fgState and fgDisplay global structures */
    case GLUT_SCREEN_WIDTH:         return fgDisplay.ScreenWidth   ;
    case GLUT_SCREEN_HEIGHT:        return fgDisplay.ScreenHeight  ;
    case GLUT_SCREEN_WIDTH_MM:      return fgDisplay.ScreenWidthMM ;
    case GLUT_SCREEN_HEIGHT_MM:     return fgDisplay.ScreenHeightMM;
    case GLUT_INIT_WINDOW_X:        return fgState.Position.X      ;
    case GLUT_INIT_WINDOW_Y:        return fgState.Position.Y      ;
    case GLUT_INIT_WINDOW_WIDTH:    return fgState.Size.X          ;
    case GLUT_INIT_WINDOW_HEIGHT:   return fgState.Size.Y          ;
    case GLUT_INIT_DISPLAY_MODE:    return fgState.DisplayMode     ;

    /*
     * The window/context specific queries are handled mostly by
     * fghGetConfig().
     */
    case GLUT_WINDOW_NUM_SAMPLES:
        /* XXX Multisampling. Return what I know about multisampling. */
        return 0;

#if TARGET_HOST_UNIX_X11
    /*
     * The rest of GLX queries under X are general enough to use a macro to
     * check them
     */
#   define GLX_QUERY(a,b) case a: return fghGetConfig( b );

    GLX_QUERY( GLUT_WINDOW_RGBA,                GLX_RGBA                );
    GLX_QUERY( GLUT_WINDOW_DOUBLEBUFFER,        GLX_DOUBLEBUFFER        );
    GLX_QUERY( GLUT_WINDOW_BUFFER_SIZE,         GLX_BUFFER_SIZE         );
    GLX_QUERY( GLUT_WINDOW_STENCIL_SIZE,        GLX_STENCIL_SIZE        );
    GLX_QUERY( GLUT_WINDOW_DEPTH_SIZE,          GLX_DEPTH_SIZE          );
    GLX_QUERY( GLUT_WINDOW_RED_SIZE,            GLX_RED_SIZE            );
    GLX_QUERY( GLUT_WINDOW_GREEN_SIZE,          GLX_GREEN_SIZE          );
    GLX_QUERY( GLUT_WINDOW_BLUE_SIZE,           GLX_BLUE_SIZE           );
    GLX_QUERY( GLUT_WINDOW_ALPHA_SIZE,          GLX_ALPHA_SIZE          );
    GLX_QUERY( GLUT_WINDOW_ACCUM_RED_SIZE,      GLX_ACCUM_RED_SIZE      );
    GLX_QUERY( GLUT_WINDOW_ACCUM_GREEN_SIZE,    GLX_ACCUM_GREEN_SIZE    );
    GLX_QUERY( GLUT_WINDOW_ACCUM_BLUE_SIZE,     GLX_ACCUM_BLUE_SIZE     );
    GLX_QUERY( GLUT_WINDOW_ACCUM_ALPHA_SIZE,    GLX_ACCUM_ALPHA_SIZE    );
    GLX_QUERY( GLUT_WINDOW_STEREO,              GLX_STEREO              );

#   undef GLX_QUERY

    /* Colormap size is handled in a bit different way than all the rest */
    case GLUT_WINDOW_COLORMAP_SIZE:
        if( (fghGetConfig( GLX_RGBA )) || (fgStructure.CurrentWindow == NULL) )
        {
            /*
             * We've got a RGBA visual, so there is no colormap at all.
             * The other possibility is that we have no current window set.
             */
            return 0;
        }
        return fgStructure.CurrentWindow->Window.VisualInfo->visual->map_entries;

    /*
     * Those calls are somewhat similiar, as they use XGetWindowAttributes()
     * function
     */
    case GLUT_WINDOW_X:
    case GLUT_WINDOW_Y:
    case GLUT_WINDOW_BORDER_WIDTH:
    case GLUT_WINDOW_HEADER_HEIGHT:
    {
        int x, y;
        Window w;

        if( fgStructure.CurrentWindow == NULL )
            return 0;

        XTranslateCoordinates(
            fgDisplay.Display,
            fgStructure.CurrentWindow->Window.Handle,
            fgDisplay.RootWindow,
            0, 0, &x, &y, &w);

//.........这里部分代码省略.........

/*
 * Sets the window status callback for the current window
 */
void FGAPIENTRY glutWindowStatusFunc( void (* callback)( int ) )
{
    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutWindowStatusFunc" );
    SET_CALLBACK( WindowStatus );
}

/*
 * Return the state of the GLUT API overlay subsystem. A misery ;-)
 */
int FGAPIENTRY glutLayerGet( GLenum eWhat )
{
    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutLayerGet" );

    /*
     * This is easy as layers are not implemented ;-)
     *
     * XXX Can we merge the UNIX/X11 and WIN32 sections?  Or
     * XXX is overlay support planned?
     */
    switch( eWhat )
    {

#if TARGET_HOST_UNIX_X11

    case GLUT_OVERLAY_POSSIBLE:
        return FALSE;

    case GLUT_LAYER_IN_USE:
        return GLUT_NORMAL;

    case GLUT_HAS_OVERLAY:
        return FALSE;

    case GLUT_TRANSPARENT_INDEX:
        /*
         * Return just anything, which is always defined as zero
         *
         * XXX HUH?
         */
        return 0;

    case GLUT_NORMAL_DAMAGED:
        /* XXX Actually I do not know. Maybe. */
        return FALSE;

    case GLUT_OVERLAY_DAMAGED:
        return -1;

#elif TARGET_HOST_WIN32 || TARGET_HOST_WINCE

    case GLUT_OVERLAY_POSSIBLE:
/*      return fgSetupPixelFormat( fgStructure.CurrentWindow, GL_TRUE,
                                   PFD_OVERLAY_PLANE ); */
      return FALSE ;

    case GLUT_LAYER_IN_USE:
        return GLUT_NORMAL;

    case GLUT_HAS_OVERLAY:
        return FALSE;

    case GLUT_TRANSPARENT_INDEX:
        /*
         * Return just anything, which is always defined as zero
         *
         * XXX HUH?
         */
        return 0;

    case GLUT_NORMAL_DAMAGED:
        /* XXX Actually I do not know. Maybe. */
        return FALSE;

    case GLUT_OVERLAY_DAMAGED:
        return -1;
#endif

    default:
        fgWarning( "glutLayerGet(): missing enum handle %d", eWhat );
        break;
    }

    /* And fail. That's good. Programs do love failing. */
    return -1;
}

/*
 * Sets the tablet buttons callback for the current window
 */
void FGAPIENTRY glutTabletButtonFunc( void (* callback)( int, int, int, int ) )
{
    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutTabletButtonFunc" );
    SET_CALLBACK( TabletButton );
}