[osg-users] zoom and orthographic projections

Robert Osfield robert.osfield at gmail.com
Thu Mar 26 07:47:37 PDT 2009


Hi Cory,

Orthographics views don't function like perspective ones, when you move near
to the center, nothing actually changes w.r.t your view.  This is normal and
what you shoudl expect.

If you want to "simulate" a perspective view by moving the left, right, top
and bottom values of the projection matrix in then it "kinda" works, but and
this is a HUGE BUT, you then hit issues what to do about the near and far
plane.  Soon you'll be trying your really hard to just and get get a
orthographic view and perspective to kinda work the same but you'll never
get to where you want to get to, perhaps some day after a few weeks of
trying you might just come to realization that it can't be done,
orthographic views just should never be used like perspetive one.

So... rather than waste much of your life, and much of our time trying to
support you give up now.  Learn that orthographic views are best kept for
external views of models where the whole model can be seen, or map views
where no issues with the near/far planes exist.  Once you get to this point
life will be good once more.

Robert.


On Thu, Mar 26, 2009 at 2:35 PM, Cory Riddell <cory at codeware.com> wrote:

> I'm calling osg::Camera::setProjectionMatrixAsOrtho() and I'm getting an
> orthographic projection (this is, if I look directly at the face of a
> cube in wireframe, all I see is a square). I can rotate and pan, but
> zoom isn't working (I'm dragging the right mouse button).
>
> I want to allow the user to toggle between perspective and orthographic
> projections. Obviously I need to do more than just set the projection
> matrix, but I'm not sure where to start looking for clues. I've been
> searching on setProjectionMatrixAsOrtho. What should I be looking for?
>
> Thanks,
> Cory Riddell
>
>
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