Implementing Stereo in Windows
[freeglut] / src / freeglut_window.c
index 7ad95d4..af29425 100644 (file)
  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
 
-#ifdef HAVE_CONFIG_H
-#include "config.h"
-#endif
-
 #include <GL/freeglut.h>
 #include "freeglut_internal.h"
 
@@ -36,7 +32,7 @@
 #include <aygshell.h>
 #pragma comment( lib, "Aygshell.lib" )
 
-wchar_t* wstr_from_str(const char* str)
+static wchar_t* fghWstrFromStr(const char* str)
 {
     int i,len=strlen(str);
     wchar_t* wstr = (wchar_t*)malloc(2*len+2);
@@ -87,12 +83,10 @@ XVisualInfo* fgChooseVisual( void )
     int attributes[ 32 ];
     int where = 0;
 
-    /*
-     * First we have to process the display mode settings...
-     */
+    /* First we have to process the display mode settings... */
 /*
- * Why is there a semi-colon in this #define?  The code
- * that uses the macro seems to always add more semicolons...
+ * XXX Why is there a semi-colon in this #define?  The code
+ * XXX that uses the macro seems to always add more semicolons...
  */
 #define ATTRIB(a) attributes[where++]=a;
 #define ATTRIB_VAL(a,v) {ATTRIB(a); ATTRIB(v);}
@@ -133,9 +127,17 @@ XVisualInfo* fgChooseVisual( void )
             ATTRIB_VAL( GLX_ACCUM_ALPHA_SIZE, 1 );
     }
 
-    /*
-     * Push a null at the end of the list
-     */
+    if( fgState.DisplayMode & GLUT_AUX1 )
+        ATTRIB_VAL( GLX_AUX_BUFFERS, 1 );
+    if( fgState.DisplayMode & GLUT_AUX2 )
+        ATTRIB_VAL( GLX_AUX_BUFFERS, 2 );
+    if( fgState.DisplayMode & GLUT_AUX3 )
+        ATTRIB_VAL( GLX_AUX_BUFFERS, 3 );
+    if( fgState.DisplayMode & GLUT_AUX4 )
+        ATTRIB_VAL( GLX_AUX_BUFFERS, 4 );
+
+
+    /* Push a null at the end of the list */
     ATTRIB( None );
 
     if( ! wantIndexedMode )
@@ -182,13 +184,14 @@ GLboolean fgSetupPixelFormat( SFG_Window* window, GLboolean checkOnly,
     if( fgState.DisplayMode & GLUT_DOUBLE )
         flags |= PFD_DOUBLEBUFFER;
 
+    if( fgState.DisplayMode & GLUT_STEREO )
+        flags |= PFD_STEREO;
+
 #if defined(_MSC_VER)
 #pragma message( "fgSetupPixelFormat(): there is still some work to do here!" )
 #endif
 
-    /*
-     * Specify which pixel format do we opt for...
-     */
+    /* Specify which pixel format do we opt for... */
     pfd.nSize           = sizeof(PIXELFORMATDESCRIPTOR);
     pfd.nVersion        = 1;
     pfd.dwFlags         = flags;
@@ -214,7 +217,17 @@ GLboolean fgSetupPixelFormat( SFG_Window* window, GLboolean checkOnly,
     pfd.cDepthBits      = 24;
     pfd.cStencilBits    = 8;
 #endif
-    pfd.cAuxBuffers     = 0;
+    if( fgState.DisplayMode & GLUT_AUX4 )
+        pfd.cAuxBuffers = 4;
+    else if( fgState.DisplayMode & GLUT_AUX3 )
+        pfd.cAuxBuffers = 3;
+    else if( fgState.DisplayMode & GLUT_AUX2 )
+        pfd.cAuxBuffers = 2;
+    else if( fgState.DisplayMode & GLUT_AUX1 )
+        pfd.cAuxBuffers = 1;
+    else
+        pfd.cAuxBuffers = 0;
+
     pfd.iLayerType      = layer_type;
     pfd.bReserved       = 0;
     pfd.dwLayerMask     = 0;
@@ -249,9 +262,9 @@ void fgSetWindow ( SFG_Window *window )
             window->Window.Context
         );
 #elif TARGET_HOST_WIN32 || TARGET_HOST_WINCE
-    if( fgStructure.Window )
-        ReleaseDC( fgStructure.Window->Window.Handle,
-                   fgStructure.Window->Window.Device );
+    if( fgStructure.CurrentWindow )
+        ReleaseDC( fgStructure.CurrentWindow->Window.Handle,
+                   fgStructure.CurrentWindow->Window.Device );
 
     if ( window )
     {
@@ -262,7 +275,7 @@ void fgSetWindow ( SFG_Window *window )
         );
     }
 #endif
-    fgStructure.Window = window;
+    fgStructure.CurrentWindow = window;
 }
 
 
@@ -280,26 +293,16 @@ void fgOpenWindow( SFG_Window* window, const char* title,
     XSizeHints sizeHints;
     XWMHints wmHints;
     unsigned long mask;
+    unsigned int current_DisplayMode = fgState.DisplayMode ;
 
-    freeglut_assert_ready;
+    /* Save the display mode if we are creating a menu window */
+    if( window->IsMenu && ( ! fgStructure.MenuContext ) )
+        fgState.DisplayMode = GLUT_DOUBLE | GLUT_RGB ;
 
-    /*
-     * XXX fgChooseVisual() is a common part of all three.
-     * XXX With a little thought, we should be able to greatly
-     * XXX simplify this.
-     */
-    if( !window->IsMenu )
-        window->Window.VisualInfo = fgChooseVisual( );
-    else if( fgStructure.MenuContext )
-        window->Window.VisualInfo = fgChooseVisual( );
-    else
-    {
-        /* XXX Why are menus double- and depth-buffered? */
-        unsigned int current_DisplayMode = fgState.DisplayMode ;
-        fgState.DisplayMode = GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH ;
-        window->Window.VisualInfo = fgChooseVisual( );
+    window->Window.VisualInfo = fgChooseVisual( );
+
+    if( window->IsMenu && ( ! fgStructure.MenuContext ) )
         fgState.DisplayMode = current_DisplayMode ;
-    }
 
     if( ! window->Window.VisualInfo )
     {
@@ -321,14 +324,8 @@ void fgOpenWindow( SFG_Window* window, const char* title,
          */
     }
 
-    /*
-     * XXX This seems to be abusing an assert() for error-checking.
-     * XXX It is possible that the visual simply can't be found,
-     * XXX in which case we should print an error and return a 0
-     * XXX for the window id, I think.
-     */
-    assert( window->Window.VisualInfo != NULL );
-
+    FREEGLUT_INTERNAL_ERROR_EXIT( window->Window.VisualInfo != NULL,
+                                  "Visual with necessary capabilities not found", "fgOpenWindow" );
 
     /*
      * XXX HINT: the masks should be updated when adding/removing callbacks.
@@ -342,7 +339,7 @@ void fgOpenWindow( SFG_Window* window, const char* title,
      */
     winAttr.event_mask        =
         StructureNotifyMask | SubstructureNotifyMask | ExposureMask |
-        ButtonPressMask | ButtonReleaseMask | KeyPressMask | KeyRelease |
+        ButtonPressMask | ButtonReleaseMask | KeyPressMask | KeyReleaseMask |
         VisibilityChangeMask | EnterWindowMask | LeaveWindowMask |
         PointerMotionMask | ButtonMotionMask;
     winAttr.background_pixmap = None;
@@ -356,7 +353,7 @@ void fgOpenWindow( SFG_Window* window, const char* title,
 
     mask = CWBackPixmap | CWBorderPixel | CWColormap | CWEventMask;
 
-    if( window->IsMenu )
+    if( window->IsMenu || ( gameMode == GL_TRUE ) )
     {
         winAttr.override_redirect = True;
         mask |= CWOverrideRedirect;
@@ -386,14 +383,14 @@ void fgOpenWindow( SFG_Window* window, const char* title,
         {
             fgStructure.MenuContext =
                 (SFG_MenuContext *)malloc( sizeof(SFG_MenuContext) );
-            fgStructure.MenuContext->VisualInfo = window->Window.VisualInfo;
-            fgStructure.MenuContext->Context = glXCreateContext(
-                fgDisplay.Display, fgStructure.MenuContext->VisualInfo,
+            fgStructure.MenuContext->MVisualInfo = window->Window.VisualInfo;
+            fgStructure.MenuContext->MContext = glXCreateContext(
+                fgDisplay.Display, fgStructure.MenuContext->MVisualInfo,
                 NULL, ( fgState.DirectContext != GLUT_FORCE_INDIRECT_CONTEXT )
             );
         }
 
-        /* window->Window.Context = fgStructure.MenuContext->Context; */
+        /* window->Window.Context = fgStructure.MenuContext->MContext; */
         window->Window.Context = glXCreateContext(
             fgDisplay.Display, window->Window.VisualInfo,
             NULL, ( fgState.DirectContext != GLUT_FORCE_INDIRECT_CONTEXT )
@@ -415,6 +412,7 @@ void fgOpenWindow( SFG_Window* window, const char* title,
             NULL, ( fgState.DirectContext != GLUT_FORCE_INDIRECT_CONTEXT )
         );
 
+#if !defined( __FreeBSD__ ) && !defined( __NetBSD__ )
     if(  !glXIsDirect( fgDisplay.Display, window->Window.Context ) )
     {
       if( fgState.DirectContext == GLUT_FORCE_DIRECT_CONTEXT )
@@ -424,6 +422,7 @@ void fgOpenWindow( SFG_Window* window, const char* title,
         fgWarning( "Unable to create direct context rendering for window '%s'\nThis may hurt performance.",
                  title );
     }
+#endif
 
     /*
      * XXX Assume the new window is visible by default
@@ -439,29 +438,20 @@ void fgOpenWindow( SFG_Window* window, const char* title,
 
     /*
      * Fill in the size hints values now (the x, y, width and height
-     * settings are obsolote, are there any more WMs that support them?)
+     * settings are obsolete, are there any more WMs that support them?)
      * Unless the X servers actually stop supporting these, we should
      * continue to fill them in.  It is *not* our place to tell the user
      * that they should replace a window manager that they like, and which
      * works, just because *we* think that it's not "modern" enough.
      */
-#if TARGET_HOST_WINCE
-    sizeHints.x      = 0;
-    sizeHints.y      = 0;
-    sizeHints.width  = 320;
-    sizeHints.height = 240;
-#else
     sizeHints.x      = x;
     sizeHints.y      = y;
     sizeHints.width  = w;
     sizeHints.height = h;
-#endif /* TARGET_HOST_WINCE */
 
     wmHints.flags = StateHint;
     wmHints.initial_state = fgState.ForceIconic ? IconicState : NormalState;
-    /*
-     * Prepare the window and iconified window names...
-     */
+    /* Prepare the window and iconified window names... */
     XStringListToTextProperty( (char **) &title, 1, &textProperty );
 
     XSetWMProperties(
@@ -475,6 +465,7 @@ void fgOpenWindow( SFG_Window* window, const char* title,
         &wmHints,
         NULL
     );
+    XFree( textProperty.value );
 
     XSetWMProtocols( fgDisplay.Display, window->Window.Handle,
                      &fgDisplay.DeleteWindow, 1 );
@@ -494,17 +485,16 @@ void fgOpenWindow( SFG_Window* window, const char* title,
     DWORD exFlags = 0;
     ATOM atom;
 
-    freeglut_assert_ready;
-
-    /*
-     * Grab the window class we have registered on glutInit():
-     */
+    /* Grab the window class we have registered on glutInit(): */
     atom = GetClassInfo( fgDisplay.Instance, _T("FREEGLUT"), &wc );
-    assert( atom != 0 );
+    FREEGLUT_INTERNAL_ERROR_EXIT ( atom, "Window Class Info Not Found",
+                                   "fgOpenWindow" );
 
     if( gameMode )
     {
-        assert( window->Parent == NULL );
+        FREEGLUT_INTERNAL_ERROR_EXIT ( window->Parent == NULL,
+                                       "Game mode being invoked on a subwindow",
+                                       "fgOpenWindow" );
 
         /*
          * Set the window creation flags appropriately to make the window
@@ -560,7 +550,7 @@ void fgOpenWindow( SFG_Window* window, const char* title,
 
 #if TARGET_HOST_WINCE
     {
-        wchar_t* wstr = wstr_from_str(title);
+        wchar_t* wstr = fghWstrFromStr(title);
 
         window->Window.Handle = CreateWindow(
             _T("FREEGLUT"),
@@ -607,7 +597,7 @@ void fgOpenWindow( SFG_Window* window, const char* title,
 #endif /* TARGET_HOST_WINCE */
 
     UpdateWindow( window->Window.Handle );
-    ShowCursor( TRUE );  /* XXX Old comments say "hide cusror"! */
+    ShowCursor( TRUE );  /* XXX Old comments say "hide cursor"! */
 
 #endif
 
@@ -628,20 +618,17 @@ void fgOpenWindow( SFG_Window* window, const char* title,
  */
 void fgCloseWindow( SFG_Window* window )
 {
-    freeglut_assert_ready;
-
 #if TARGET_HOST_UNIX_X11
 
     glXDestroyContext( fgDisplay.Display, window->Window.Context );
+    XFree( window->Window.VisualInfo );
     XDestroyWindow( fgDisplay.Display, window->Window.Handle );
     XFlush( fgDisplay.Display ); /* XXX Shouldn't need this */
 
 #elif TARGET_HOST_WIN32 || TARGET_HOST_WINCE
 
-    /*
-     * Make sure we don't close a window with current context active
-     */
-    if( fgStructure.Window == window )
+    /* Make sure we don't close a window with current context active */
+    if( fgStructure.CurrentWindow == window )
         wglMakeCurrent( NULL, NULL );
 
     /*
@@ -677,6 +664,14 @@ void fgCloseWindow( SFG_Window* window )
  */
 int FGAPIENTRY glutCreateWindow( const char* title )
 {
+    /* XXX GLUT does not exit; it simply calls "glutInit" quietly if the
+     * XXX application has not already done so.  The "freeglut" community
+     * XXX decided not to go this route (freeglut-developer e-mail from
+     * XXX Steve Baker, 12/16/04, 4:22 PM CST, "Re: [Freeglut-developer]
+     * XXX Desired 'freeglut' behaviour when there is no current window"
+     */
+    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutCreateWindow" );
+
     return fgCreateWindow( NULL, title, fgState.Position.X, fgState.Position.Y,
                            fgState.Size.X, fgState.Size.Y, GL_FALSE,
                            GL_FALSE )->ID;
@@ -688,13 +683,38 @@ int FGAPIENTRY glutCreateWindow( const char* title )
 int FGAPIENTRY glutCreateSubWindow( int parentID, int x, int y, int w, int h )
 {
     int ret = 0;
-
     SFG_Window* window = NULL;
     SFG_Window* parent = NULL;
 
-    freeglut_assert_ready;
+    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutCreateSubWindow" );
     parent = fgWindowByID( parentID );
     freeglut_return_val_if_fail( parent != NULL, 0 );
+    if ( x < 0 )
+    {
+        x = parent->State.Width + x ;
+        if ( w >= 0 ) x -= w ;
+    }
+
+    if ( w < 0 ) w = parent->State.Width - x + w ;
+    if ( w < 0 )
+    {
+        x += w ;
+        w = -w ;
+    }
+
+    if ( y < 0 )
+    {
+        y = parent->State.Height + y ;
+        if ( h >= 0 ) y -= h ;
+    }
+
+    if ( h < 0 ) h = parent->State.Height - y + h ;
+    if ( h < 0 )
+    {
+        y += h ;
+        h = -h ;
+    }
+
     window = fgCreateWindow( parent, "", x, y, w, h, GL_FALSE, GL_FALSE );
     ret = window->ID;
 
@@ -706,7 +726,9 @@ int FGAPIENTRY glutCreateSubWindow( int parentID, int x, int y, int w, int h )
  */
 void FGAPIENTRY glutDestroyWindow( int windowID )
 {
-    SFG_Window* window = fgWindowByID( windowID );
+    SFG_Window* window;
+    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutDestroyWindow" );
+    window = fgWindowByID( windowID );
     freeglut_return_if_fail( window != NULL );
     {
         fgExecutionState ExecState = fgState.ExecState;
@@ -722,15 +744,15 @@ void FGAPIENTRY glutSetWindow( int ID )
 {
     SFG_Window* window = NULL;
 
-    freeglut_assert_ready;
-    if( fgStructure.Window != NULL )
-        if( fgStructure.Window->ID == ID )
+    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutSetWindow" );
+    if( fgStructure.CurrentWindow != NULL )
+        if( fgStructure.CurrentWindow->ID == ID )
             return;
 
     window = fgWindowByID( ID );
     if( window == NULL )
     {
-        fgWarning( "glutSetWindow(): window ID %i not found!", ID );
+        fgWarning( "glutSetWindow(): window ID %d not found!", ID );
         return;
     }
 
@@ -742,10 +764,10 @@ void FGAPIENTRY glutSetWindow( int ID )
  */
 int FGAPIENTRY glutGetWindow( void )
 {
-    freeglut_assert_ready;
-    if( fgStructure.Window == NULL )
+    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutGetWindow" );
+    if( fgStructure.CurrentWindow == NULL )
         return 0;
-    return fgStructure.Window->ID;
+    return fgStructure.CurrentWindow->ID;
 }
 
 /*
@@ -753,21 +775,21 @@ int FGAPIENTRY glutGetWindow( void )
  */
 void FGAPIENTRY glutShowWindow( void )
 {
-    freeglut_assert_ready;
-    freeglut_assert_window;
+    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutShowWindow" );
+    FREEGLUT_EXIT_IF_NO_WINDOW ( "glutShowWindow" );
 
 #if TARGET_HOST_UNIX_X11
 
-    XMapWindow( fgDisplay.Display, fgStructure.Window->Window.Handle );
+    XMapWindow( fgDisplay.Display, fgStructure.CurrentWindow->Window.Handle );
     XFlush( fgDisplay.Display ); /* XXX Shouldn't need this */
 
 #elif TARGET_HOST_WIN32 || TARGET_HOST_WINCE
 
-    ShowWindow( fgStructure.Window->Window.Handle, SW_SHOW );
+    ShowWindow( fgStructure.CurrentWindow->Window.Handle, SW_SHOW );
 
 #endif
 
-    fgStructure.Window->State.Redisplay = GL_TRUE;
+    fgStructure.CurrentWindow->State.Redisplay = GL_TRUE;
 }
 
 /*
@@ -775,27 +797,27 @@ void FGAPIENTRY glutShowWindow( void )
  */
 void FGAPIENTRY glutHideWindow( void )
 {
-    freeglut_assert_ready;
-    freeglut_assert_window;
+    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutHideWindow" );
+    FREEGLUT_EXIT_IF_NO_WINDOW ( "glutHideWindow" );
 
 #if TARGET_HOST_UNIX_X11
 
-    if( fgStructure.Window->Parent == NULL )
+    if( fgStructure.CurrentWindow->Parent == NULL )
         XWithdrawWindow( fgDisplay.Display,
-                         fgStructure.Window->Window.Handle,
+                         fgStructure.CurrentWindow->Window.Handle,
                          fgDisplay.Screen );
     else
         XUnmapWindow( fgDisplay.Display,
-                      fgStructure.Window->Window.Handle );
+                      fgStructure.CurrentWindow->Window.Handle );
     XFlush( fgDisplay.Display ); /* XXX Shouldn't need this */
 
 #elif TARGET_HOST_WIN32 || TARGET_HOST_WINCE
 
-    ShowWindow( fgStructure.Window->Window.Handle, SW_HIDE );
+    ShowWindow( fgStructure.CurrentWindow->Window.Handle, SW_HIDE );
 
 #endif
 
-    fgStructure.Window->State.Redisplay = GL_FALSE;
+    fgStructure.CurrentWindow->State.Redisplay = GL_FALSE;
 }
 
 /*
@@ -803,23 +825,23 @@ void FGAPIENTRY glutHideWindow( void )
  */
 void FGAPIENTRY glutIconifyWindow( void )
 {
-    freeglut_assert_ready;
-    freeglut_assert_window;
+    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutIconifyWindow" );
+    FREEGLUT_EXIT_IF_NO_WINDOW ( "glutIconifyWindow" );
 
-    fgStructure.Window->State.Visible   = GL_FALSE;
+    fgStructure.CurrentWindow->State.Visible   = GL_FALSE;
 #if TARGET_HOST_UNIX_X11
 
-    XIconifyWindow( fgDisplay.Display, fgStructure.Window->Window.Handle,
+    XIconifyWindow( fgDisplay.Display, fgStructure.CurrentWindow->Window.Handle,
                     fgDisplay.Screen );
     XFlush( fgDisplay.Display ); /* XXX Shouldn't need this */
 
 #elif TARGET_HOST_WIN32 || TARGET_HOST_WINCE
 
-    ShowWindow( fgStructure.Window->Window.Handle, SW_MINIMIZE );
+    ShowWindow( fgStructure.CurrentWindow->Window.Handle, SW_MINIMIZE );
 
 #endif
 
-    fgStructure.Window->State.Redisplay = GL_FALSE;
+    fgStructure.CurrentWindow->State.Redisplay = GL_FALSE;
 }
 
 /*
@@ -827,9 +849,9 @@ void FGAPIENTRY glutIconifyWindow( void )
  */
 void FGAPIENTRY glutSetWindowTitle( const char* title )
 {
-    freeglut_assert_ready;
-    freeglut_assert_window;
-    if( ! fgStructure.Window->Parent )
+    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutSetWindowTitle" );
+    FREEGLUT_EXIT_IF_NO_WINDOW ( "glutSetWindowTitle" );
+    if( ! fgStructure.CurrentWindow->Parent )
     {
 #if TARGET_HOST_UNIX_X11
 
@@ -842,7 +864,7 @@ void FGAPIENTRY glutSetWindowTitle( const char* title )
 
         XSetWMName(
             fgDisplay.Display,
-            fgStructure.Window->Window.Handle,
+            fgStructure.CurrentWindow->Window.Handle,
             &text
         );
 
@@ -850,13 +872,13 @@ void FGAPIENTRY glutSetWindowTitle( const char* title )
 
 #elif TARGET_HOST_WIN32
 
-        SetWindowText( fgStructure.Window->Window.Handle, title );
+        SetWindowText( fgStructure.CurrentWindow->Window.Handle, title );
 
 #elif TARGET_HOST_WINCE
         {
-            wchar_t* wstr = wstr_from_str(title);
+            wchar_t* wstr = fghWstrFromStr(title);
 
-            SetWindowText( fgStructure.Window->Window.Handle, wstr );
+            SetWindowText( fgStructure.CurrentWindow->Window.Handle, wstr );
 
             free(wstr);
         }
@@ -869,10 +891,10 @@ void FGAPIENTRY glutSetWindowTitle( const char* title )
  */
 void FGAPIENTRY glutSetIconTitle( const char* title )
 {
-    freeglut_assert_ready;
-    freeglut_assert_window;
+    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutSetIconTitle" );
+    FREEGLUT_EXIT_IF_NO_WINDOW ( "glutSetIconTitle" );
 
-    if( ! fgStructure.Window->Parent )
+    if( ! fgStructure.CurrentWindow->Parent )
     {
 #if TARGET_HOST_UNIX_X11
 
@@ -885,7 +907,7 @@ void FGAPIENTRY glutSetIconTitle( const char* title )
 
         XSetWMIconName(
             fgDisplay.Display,
-            fgStructure.Window->Window.Handle,
+            fgStructure.CurrentWindow->Window.Handle,
             &text
         );
 
@@ -893,13 +915,13 @@ void FGAPIENTRY glutSetIconTitle( const char* title )
 
 #elif TARGET_HOST_WIN32
 
-        SetWindowText( fgStructure.Window->Window.Handle, title );
+        SetWindowText( fgStructure.CurrentWindow->Window.Handle, title );
 
 #elif TARGET_HOST_WINCE
         {
-            wchar_t* wstr = wstr_from_str(title);
+            wchar_t* wstr = fghWstrFromStr(title);
 
-            SetWindowText( fgStructure.Window->Window.Handle, wstr );
+            SetWindowText( fgStructure.CurrentWindow->Window.Handle, wstr );
 
             free(wstr);
         }
@@ -912,12 +934,12 @@ void FGAPIENTRY glutSetIconTitle( const char* title )
  */
 void FGAPIENTRY glutReshapeWindow( int width, int height )
 {
-    freeglut_assert_ready;
-    freeglut_assert_window;
+    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutReshapeWindow" );
+    FREEGLUT_EXIT_IF_NO_WINDOW ( "glutReshapeWindow" );
 
-    fgStructure.Window->State.NeedToResize = GL_TRUE;
-    fgStructure.Window->State.Width  = width ;
-    fgStructure.Window->State.Height = height;
+    fgStructure.CurrentWindow->State.NeedToResize = GL_TRUE;
+    fgStructure.CurrentWindow->State.Width  = width ;
+    fgStructure.CurrentWindow->State.Height = height;
 }
 
 /*
@@ -925,12 +947,12 @@ void FGAPIENTRY glutReshapeWindow( int width, int height )
  */
 void FGAPIENTRY glutPositionWindow( int x, int y )
 {
-    freeglut_assert_ready;
-    freeglut_assert_window;
+    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutPositionWindow" );
+    FREEGLUT_EXIT_IF_NO_WINDOW ( "glutPositionWindow" );
 
 #if TARGET_HOST_UNIX_X11
 
-    XMoveWindow( fgDisplay.Display, fgStructure.Window->Window.Handle,
+    XMoveWindow( fgDisplay.Display, fgStructure.CurrentWindow->Window.Handle,
                  x, y );
     XFlush( fgDisplay.Display ); /* XXX Shouldn't need this */
 
@@ -939,9 +961,10 @@ void FGAPIENTRY glutPositionWindow( int x, int y )
     {
         RECT winRect;
 
-        GetWindowRect( fgStructure.Window->Window.Handle, &winRect );
+        /* "GetWindowRect" returns the pixel coordinates of the outside of the window */
+        GetWindowRect( fgStructure.CurrentWindow->Window.Handle, &winRect );
         MoveWindow(
-            fgStructure.Window->Window.Handle,
+            fgStructure.CurrentWindow->Window.Handle,
             x,
             y,
             winRect.right - winRect.left,
@@ -958,17 +981,17 @@ void FGAPIENTRY glutPositionWindow( int x, int y )
  */
 void FGAPIENTRY glutPushWindow( void )
 {
-    freeglut_assert_ready;
-    freeglut_assert_window;
+    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutPushWindow" );
+    FREEGLUT_EXIT_IF_NO_WINDOW ( "glutPushWindow" );
 
 #if TARGET_HOST_UNIX_X11
 
-    XLowerWindow( fgDisplay.Display, fgStructure.Window->Window.Handle );
+    XLowerWindow( fgDisplay.Display, fgStructure.CurrentWindow->Window.Handle );
 
 #elif TARGET_HOST_WIN32 || TARGET_HOST_WINCE
 
     SetWindowPos(
-        fgStructure.Window->Window.Handle,
+        fgStructure.CurrentWindow->Window.Handle,
         HWND_BOTTOM,
         0, 0, 0, 0,
         SWP_NOSIZE | SWP_NOMOVE
@@ -982,17 +1005,17 @@ void FGAPIENTRY glutPushWindow( void )
  */
 void FGAPIENTRY glutPopWindow( void )
 {
-    freeglut_assert_ready;
-    freeglut_assert_window;
+    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutPopWindow" );
+    FREEGLUT_EXIT_IF_NO_WINDOW ( "glutPopWindow" );
 
 #if TARGET_HOST_UNIX_X11
 
-    XRaiseWindow( fgDisplay.Display, fgStructure.Window->Window.Handle );
+    XRaiseWindow( fgDisplay.Display, fgStructure.CurrentWindow->Window.Handle );
 
 #elif TARGET_HOST_WIN32 || TARGET_HOST_WINCE
 
     SetWindowPos(
-        fgStructure.Window->Window.Handle,
+        fgStructure.CurrentWindow->Window.Handle,
         HWND_TOP,
         0, 0, 0, 0,
         SWP_NOSIZE | SWP_NOMOVE
@@ -1006,8 +1029,8 @@ void FGAPIENTRY glutPopWindow( void )
  */
 void FGAPIENTRY glutFullScreen( void )
 {
-    freeglut_assert_ready;
-    freeglut_assert_window;
+    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutFullScreen" );
+    FREEGLUT_EXIT_IF_NO_WINDOW ( "glutFullScreen" );
 
     {
 #if TARGET_HOST_UNIX_X11
@@ -1016,7 +1039,7 @@ void FGAPIENTRY glutFullScreen( void )
 
         XMoveResizeWindow(
             fgDisplay.Display,
-            fgStructure.Window->Window.Handle,
+            fgStructure.CurrentWindow->Window.Handle,
             0, 0,
             fgDisplay.ScreenWidth,
             fgDisplay.ScreenHeight
@@ -1026,7 +1049,7 @@ void FGAPIENTRY glutFullScreen( void )
 
         XTranslateCoordinates(
             fgDisplay.Display,
-            fgStructure.Window->Window.Handle,
+            fgStructure.CurrentWindow->Window.Handle,
             fgDisplay.RootWindow,
             0, 0, &x, &y, &w
         );
@@ -1035,7 +1058,7 @@ void FGAPIENTRY glutFullScreen( void )
         {
             XMoveWindow(
                 fgDisplay.Display,
-                fgStructure.Window->Window.Handle,
+                fgStructure.CurrentWindow->Window.Handle,
                 -x, -y
             );
             XFlush( fgDisplay.Display ); /* XXX Shouldn't need this */
@@ -1063,7 +1086,7 @@ void FGAPIENTRY glutFullScreen( void )
          * SWP_NOZORDER       Retains the current Z order (ignore 2nd param)
          */
 
-        SetWindowPos( fgStructure.Window->Window.Handle,
+        SetWindowPos( fgStructure.CurrentWindow->Window.Handle,
                       HWND_TOP,
                       rect.left,
                       rect.top,
@@ -1081,12 +1104,16 @@ void FGAPIENTRY glutFullScreen( void )
  */
 void* FGAPIENTRY glutGetWindowData( void )
 {
-    return fgStructure.Window->UserData;
+    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutGetWindowData" );
+    FREEGLUT_EXIT_IF_NO_WINDOW ( "glutGetWindowData" );
+    return fgStructure.CurrentWindow->UserData;
 }
 
 void FGAPIENTRY glutSetWindowData(void* data)
 {
-    fgStructure.Window->UserData = data;
+    FREEGLUT_EXIT_IF_NOT_INITIALISED ( "glutSetWindowData" );
+    FREEGLUT_EXIT_IF_NO_WINDOW ( "glutSetWindowData" );
+    fgStructure.CurrentWindow->UserData = data;
 }
 
 /*** END OF FILE ***/