Hi Enrico,
On Wed, 2005-06-08 at 18:04 +0200, Enrico Borrione wrote:
> hi OpenSG users...
> i have a small problem, yet quite puzzling.
> I have built the roof of the cave i am using
> in my experiments and... i discovered that i
> need to change the aspect ratio of the upper
> projection.
>
> I mean... on the three walls i have 3 separate
> projections using the standard 3:4 aspect ratio,
> which is natural since the screens are rectangular.
> The roof on the other side is square, so my projection
> is right in the "horizontal" axis and shortened in
> the "vertical".
> I think that i have to use the aspect field of my perspective
> cameras, to correct this bad side-effect, but since
> it is the first time that i come across this kind of trouble i was
> wondering if someone already solved it.
are you using a ProjectionCameraDecorator for your Cave? If yes, you can
ignore the aspect problem, just set your corners right and things will
work.
> What aspect ratio should i use??? 1:1????
> Does the correct syntax sound like:
>
> camera->setAspect (1.0);
> ????
>
> where 1.0 is the result of horizontal-pixel/vertical-pixel length???
It depends on what the aspect ratio of the pixels of your projection is.
The easiest way to measure that is to display a 100x100 pixel rectangle
(a simple image will do), measure it's size on screen and use
width/height as the aspect ratio.
Just make sure that your display window actually only fills the visible
part (most projectors nowadays have a fixed aspect ratio != 1, so for
your Cave only a part of the projected pixels are visible).
Hope it helps
Dirk
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