Adding a comment on why \"freeglut\" differs from GLUT in a particular way

[freeglut] / src / freeglut_window.c

diff --git a/src/freeglut_window.c b/src/freeglut_window.c
index 5e9d791..277fe26 100644 (file)
--- a/src/freeglut_window.c
+++ b/src/freeglut_window.c
@@ -659,6 +659,12 @@ 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,
@@ -678,6 +684,32 @@ int FGAPIENTRY glutCreateSubWindow( int parentID, int x, int y, int w, int h )
     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;