Hey guys,

This isn't a 100% OpenGL question but I'll limit this to the
appropriate part. What I'd like to know is weather OpenGL can render
directly to the screen without a window system in-place acting as
intermediary i.e. X.

There doesn't seem to be much info here but you can do things with the
full screen so I can conjuncture that it's possible, but I'd like a
confirmation if possible :).

Thanks a lot,

Mark.

netytan@gmail.com wrote:
> Hey guys,
> 
> This isn't a 100% OpenGL question but I'll limit this to the
> appropriate part. What I'd like to know is weather OpenGL can render
> directly to the screen without a window system in-place acting as
> intermediary i.e. X.
> 

No.

Look at the OpenGL API and you'll see that there's
no functions defining "screen", "framebuffer" or
anything like that.

OpenGL always depends on some external library to
create a place where it can render.

There's a movement in the Linux World to swap things
around so that OpenGL is the lowest layer of the
graphics system (ie. that X uses OpenGL for rendering)
but it's still fairly "beta".


-- 
<\___/>
/ O O \
\_____/  FTB.    For email, remove my socks.

In science it often happens that scientists say, 'You know
that's a really good argument; my position is mistaken,'
and then they actually change their minds and you never
hear that old view from them again.  They really do it.
It doesn't happen as often as it should, because scientists
are human and change is sometimes painful.  But it happens
every day.  I cannot recall the last time something like
that happened in politics or religion.

- Carl Sagan, 1987 CSICOP keynote address

netytan@gmail.com wrote:

> Hey guys,
> 
> This isn't a 100% OpenGL question but I'll limit this to the
> appropriate part. What I'd like to know is weather OpenGL can render
> directly to the screen without a window system in-place acting as
> intermediary i.e. X.

Yes, Mesa can do that on some platforms, but you probably NOT get hardware 
acceleration that way.


-- 
Phil Frisbie, Jr.
Hawk Software
http://www.hawksoft.com

netytan@gmail.com wrote:
> Hey guys,
>
> This isn't a 100% OpenGL question but I'll limit this to the
> appropriate part. What I'd like to know is weather OpenGL can render
> directly to the screen without a window system in-place acting as
> intermediary i.e. X.
>
> There doesn't seem to be much info here but you can do things with the
> full screen so I can conjuncture that it's possible, but I'd like a
> confirmation if possible :).
>
> Thanks a lot,
>
> Mark.


You always need some degree of "glue" to help OpenGL out.  On some
embedded platforms, this "glue" may be very little, and not include a
windowing system.  But, you need to initialise the display, and do a
few basic things before it is possible to start rendering.  What
platform are you using?  You may want to try checking with a group
dedicated to that platorm.  OpenGL doesn't really care if it has the
full screen, or is in a multiwindowed environment.  OpenGL doesn't
directly have any functionality that deals with windows.

Why is it that you are so keen on not having a windowing system?

>From a purely philosophical perspective, the OpenGL spec allows for
operation without a window system.

However, I don't know of any such implementations. All OpenGL
implementations I know of depend on a window-system specific API such
as WGL, GLX, AGL, etc for creation of a rendering context and drawing
surface. Some of these APIs let you create a fullscreen drawing
surface, which might be what you want.

The OpenGL spec itself says state is stored in a rendering context, and
doesn't refer to rendering surfaces explicitly. So, I could imagine an
OpenGL implementation that provides one rendering context that takes
over and renders to the whole screen when your app starts up. Not too
practical in today's window system environments though.

I have this blue notebook in which I keep all my ideas and other useful
notes on programming and CS in general. Recently I was going back
through it and at one point in there I was interested in writing my own
GUI layer over an OS - this should be generic but *nix is my primary
platform.

I'm not a fan of the whole WIMPs thing. The whole idea of having a
desktop implies poor organization and use of space etc. just look at
real desktops and ask why we're mapping our thoughts onto them ;).
Right now I'm scoping out the necessary libs I'll need to implement a
basic GUI that can be scripted and extended by the user.

Thanks for your advice guys,

Mark.