[osg-users] "fovx" and "fovy"

[Paul Martz]

> Hi Paul,
> 
> The field of view is governed by the cameras projection 
> matrix.  The default projection matrix used is controlled via 
> the OSG_SCREEN_DISTANCE, OSG_SCREEN_HEIGHT and 
> OSG_SCREEEN_WIDTH if they are set, otherwise its defaults for 
> these are chosen, or the application itself sets the 
> projection matrix and hence the fov-x/fov-y.

Okay, I understand that "if you are setting fovx and fovy explicityly"
refers to anything you might do in your app to set a non-default FOV.

However, isn't it possible a user might still want their aspect ratio
automatically adjusted for split screen stereo, even if they set a
non-default FOV? The help text message implies the user should always
disable aspect ratio auto adjustment in such a case. I'm not sure why. Maybe
for the case where the user has set the FOV explicitly and _also_ has
already compensated for the split screen stereo aspect ratio...?

Thanks,
   -Paul


> It might be appropriate to tweak the language of this comment 
> to better reflect the above.
> 
> Robert.
> 
> On Dec 10, 2007 9:40 PM, Paul Martz <pmartz at skew-matrix.com> wrote:
> >
> >
> > Hi Robert -- If I do "osgviewer --help-env", one of the displayed 
> > environment variables is OSG_SPLIT_STEREO_AUTO_ADJUST_ASPECT_RATIO, 
> > with the following description:
> >
> > Default to ON to compenstate for the compression of the 
> aspect ratio 
> > when viewing in split screen stereo.  Note, if you are setting fovx 
> > and fovy explicityly OFF should be used.
> > However, no where in the --help-env output is any mention 
> of either "fovx"
> > or "fovy", or how you would set them. Can you please elaborate on 
> > these values refer to?
> >
> > This is for my environment variable reference. In my 
> description for 
> > OSG_SPLIT_STEREO_AUTO_ADJUST_ASPECT_RATIO, I'd like to include text 
> > telling users that this should be set to OFF if they are setting 
> > "fovx" or "fovy", but I need to know what "fovx" and "fovy" are 
> > referring to and how a user would set them. Thanks.
> >
> > I see this is used in SceneView to compute the left and right eye 
> > projection scale factors, but I don't see any other way to 
> set these scale factors.
> > Perhaps the message is simply out of date.
> >
> > Paul Martz
> > Skew Matrix Software LLC
> > http://www.skew-matrix.com
> > 303 859 9466
> >
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> > 
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> >
> >
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