[vtkusers] Windows offscreen image rendering

Ermin Hasičević Ermin.Hasicevic at iskon.hr
Tue Sep 11 18:15:48 EDT 2001

Thank God, vtkWin32OffscreenRenderWindow actually works. :)
But, how can I achieve that coordinates off poly data that's rendered
in that window and dumped into the image file actually correspond
whit real coordinates of poly data. In image it seems that polygon
is somehow stretched. I suppose I should set some properties of
the camera but I don't know what are the values for these settings.
-----Original Message----- 
From: John Biddiscombe 
Sent: pon 10.09.01 11:18 
To: Ermin Hasičević; vtkusers at public.kitware.com 
Subject: RE: [vtkusers] Windows offscreen image rendering

	 From the list a few weeks ago.....the offscreen renderwindow
sounds like
	what you want, but I for one know nothing about it.
	Date: Thu, 9 Aug 2001 12:51:52 -0500 (CDT)
	From: Tony Lavoie <lavoie at mcs.anl.gov>
	To: vtkusers at public.kitware.com
	Subject: Re: [vtkusers] About OffScreen Question ^_^
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	I went looking int off-screen rendering as well, and I tried the
	vtkOffScreen code. First, on Linux (Unix/OpenGL/X11 systems as
it says),
	it links against the Mesa libs, which has offscreen rendering if
	glance through vtkMesaRenderWindow.cxx. I looked into OpenGL
support of
	offscreen rendering, and found that the blue book (OpenGL
	Manual, OpenGL ARB) says that pbuffers and pixmaps are only
implemented in
	GLX 1.3, and 1.3 afaik is only available for SGI's- 1.3 for
Linux & Mac is
	"Coming Soon..."
	-Tony . o O ( c'mon nVidia, GLX 1.3 on GeForce3's!! )
	On Thu, 9 Aug 2001, David Homiak wrote:
	 > Kevin,
	 >       See http://infinite-entropy.lbl.gov/VTK/vtkOffScreen/
for a
	 > vtkOpenGLOffscreenRenderWindow class. From there description:
	 >       "Use in place of a vtkRenderWindow to draw an offscreen
image. This
	 > is specifically for Unix/OpenGL/X11 systems. There is already
	 > vtkWin32OffscreenRenderWindow in the contrib directory of VTK
to cover
	 > Windows systems. For SGI systems, it will use pbuffers for
	 > accelerated offscreen rendering. For all other architectures,
it will use
	 > GLX pixmaps which tend to be software-rendering (except for
	 > hardware-accelerated Mesa)."
	 >       More generally for X11 on UNIX, there is also Xvfb, the
X virtual
	 > frame buffer. Do a Google search on it and also check out
	 > http://starbase.neosoft.com/~claird/comp.windows.x/Xvfb.html.
I have used
	 > Xvfb in the past to do X processing on headless Sun servers
lacking graphics
	 > cards.
	 > Dave Homiak
	 > dhomiak at xcaliber.com
	 > Results! Why, man, I have gotten a lot of results. I know
several thousand
	 > things that won't work.    --   Thomas Edison
	 > > Date: Wed, 08 Aug 2001 17:22:20 +0800
	 > > From: Lin Sun-In <lsi at nchc.gov.tw>
	 > > To: vtkusers at public.kitware.com
	 > > Subject: [vtkusers] About OffScreen Question ^_^
	 > >
	 > > Dear VTK author:
	 > >
	 > >     I have a problem about VTK. We know OpenGL fo Win32 has
	 > > offscreen function , and VTK for Win32 also provide similar
	 > > But now I want to try this feature in Unix-like platform,
but i have no
	 > > idea. Could you please tell me any solution about this.
	 > >
	 > > PS : Because I want to run VTK program in the background,
but the
	 > > RenderWindow need a X-Window Server to display the result.
So I must
	 > > login to take a window manager or set the "DISPLAY"
environment variable
	 > > to transfer the display to another machine. But I want to
have the same
	 > > function in Win32 OS ==> "offscreen". Could you please tell
me how can i
	 > > do it ????
	 > >
	 > >                             Kevin
	 > _______________________________________________
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	At 12:53 09/09/2001, =?utf-8?Q?Ermin_Hasi=C4=8Devi=C4=87?=
	>         -----Original Message-----
	>         From: John Biddiscombe
	>         Sent: sub 08.09.01 19:04
	>         To: Ermin Hasičević; vtkusers at public.kitware.com
	>         Cc:
	>         Subject: Re: [vtkusers] Windows offscreen image
	>              renWin->SetupMemoryRendering(width, height,
	>         (HDC)renWin->GetGenericContext());
	>              renWin->Render();
	>         // do stuff with bitmap
	>              renWin->ResumeScreenRendering();
	>         > have used this successfully, but note that it
stopped working
	>some time
	>         >(I don't know when - I didn't use it for months) and
when I
	>tried it last
	>         >week it gave an image of width & height of zero (ie
nothing). I
	>checked in
	>         >a fix a few days ago and my offscreen rendering is
working fine
	>         >maybe you should try a nightly release from today or
	>and give it a go.
	>         >
	>         >If you're using an older vtk, you should probably
just get
	>         >vtkWin32OpenGLRenderWindow from cvs
	>         >(Note that the above assumes you already have a
	>device context
	>         >on screen, if you are doing vtk without a window you
might need
	>         >else...)
	>         >JB
	>         I don't know if I misunderstood concept of offscreen
	>but I thought
	>         that it's such kind of rendering where no image window
pops out
	>when I start
	>         image rendering. Is there any way to tell
	>window to
	>         not show when I call render method for first time or
there's no
	>hope to get away
	>         from that?
	>         Ermin

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