[osg-users] A question about zooming with orthographic projection

[Robert Osfield]

Hi Ke Li,

You can do othrographic projection just fine, no need to avoid it.
The thing to avoid is zooming into a scene when in orthographic
projection - this is something that is just plain broken, you can try
tricks with near/far clipping but in the end you'll need to come round
the conclusion that its broken and is an inappropriate use of
orthographic projection.  Is say this from hard experience over the
years trying to juggle orthographic and perspective views.

Another broken idea that some apps try to do is stereo and
orthographic projections of scenes.... It's completely bonkers but
some people do it and expect it to work.

Use orthographic for what it's good at - external views of scenes,
maps, text overlays.

Robert.

On Tue, Mar 18, 2008 at 6:55 PM, Ke Li <hetwice at hotmail.com> wrote:
>
>  Dear all,
>
>  In the following post, Robert said that orthographic projection should be
> avoided.
>
>
> http://thread.gmane.org/gmane.comp.graphics.openscenegraph.user/7660/focus=7664
>
>  But I know that some OpenGL applications do use orthographic projection
> with zooming functionality. So I'm a little confused.
>
>  Can any one give me some enlightenment?
>
>  Thanks!
>
>  Ke Li
>
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