Re: [Freeglut-developer] X screensaver damage

[John T. <nu...@me...>]

On Tue, Jul 02, 2013 at 09:52:42AM -0400, Jean-Claude Gervais wrote:
>     If I perform the initialization in THIS order, the problem is
> solved!
>     glutInit( &argc, argv );
>     glutInitDisplayMode( GLUT_DOUBLE | GLUT_RGB );
>     glutInitWindowSize( 800, 600 );
>     glutCreateWindow( "test" );
> 
>     If I perform the initialization in this order, the problem
> manifests:
>     glutInit( &argc, argv );
>     glutInitWindowSize( 800, 600 );
>     glutCreateWindow( "test" );
>     glutInitDisplayMode( GLUT_DOUBLE | GLUT_RGB );

Of course. The various glutInit* calls are used to set the window and
context options for the next window/context that will be created. They
are then used by glutCreateWindow which actually creates the window with
a bound OpenGL context.

In your second ordering, glutCreateWindow creates a window with default
context parameters (single buffered if available), and your requested
parameters would only take effect if you create another window by
calling glutCreateWidnow again afterwards.

>     The only difference is the order of calling glutInitDisplayMode !

Quite an important difference.

>     I'm certain that there is a good reason for this and my being
> relatively new to OpenGL is why I got tripped-up by it.

This has nothing to do with OpenGL.

-- 
John Tsiombikas
http://nuclear.mutantstargoat.com/