Re: glReadPixels and viewport problem

On Thursday 27 November 2003 01.54, Paulo Jorge de Oliveira Cantante de=
 Matos=20
wrote:
> Hi Marten,
>
> Thanks a lot for the help, that was indeed the problem. :D It's
> everything working now! :D

Good!

> I've subscribed two weeks ago and your message was the first I've
> received. :Dhehe, unfortunately it seems inactive! :(

This is a little strange. Personally I use both Linux and OpenGL a lot,=
 and it=20
is a powerful combination. Exchanging experience in these fields would =
seem=20
like a natural thing to do. Maybe there are more focused forums for eac=
h of=20
the topics?

Is this list REALLY dead?? (come on!)

/Marten

>
> Best regards,
>
> Paulo Matos
>
> On Wed, 2003-11-26 at 23:58, M=E5rten Str=F6mberg wrote:
> > Paulo,
> >
> > Try the following before calling glReadPixels:
> >
> >   glPixelStorei(GL_PACK_ALIGNMENT, 1);
> >
> > I believe it defaults to 4, which is not a divisor of 250.
> >
> > BTW, I did not remember being subscribed to linux-opengl! Is the li=
st
> > still active?
> >
> > Regards,
> > Marten
> >
> >
> > On Thursday 27 November 2003 00.35, Paulo Jorge de Oliveira Cantant=
e de
> > Matos
> >
> > wrote:
> > > Hi all,
> > >
> > > I'm developing an application in which I get the viewport through
> > > glReadPixels and then I write it in to a PPM file. A situation
> > > depending on the viewport size arises. If the viewport is 250x250=
, the
> > > buffer returned from glReadPixels shows the viewport in 'italic' =
(the
> > > image is incorrect), a vertical line comes as a diagonal for exam=
ple.
> > > However, if size is 500x500, everything is fine. Other similar
> > > situations arise depending on the viewport size. This is indeed
> > > strange, I've not set any state variable relating to glReadPixels=
, do I
> > > need to set or enable any special variable? Is this a known issue=
?
> > >
> > > I've decided not to include any code, if you would like some code=
 to
> > > test it, I'll be happy to send it to you privately.
> > >
> > > Oh, and the problem is not in the procedure that writes the PPM f=
ile
> > > from the glReadPixels buffer since it was tested by some people a=
nd all
> > > get the same results with glReadPixels (I cannot assure you it's =
not in
> > > the PPM file but it's not probable).
> > >
> > > Best regards,

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