Hello Venkat,
On 01/31/2013 03:48 AM, Venkat (OpenSG) wrote:
> I am able to use an orthographic camera with simple scene manager,
> however the zoom in/out does not work though rotation works correctly.
> I see that the projection matrix returned by the orthographic camera has
> the z-translation component zero, this I believe that this is the reason
> for the zoom issue. What would the best way to implement zoom in/out?
>
> The only way I can think of is to store an external variable for the
> zoom factor and set the camera horizontal/vertical size before draw but
> I was hoping to avoid that and use the built-in navigator functionality.
the built-in navigators don't really perform a zoom, they translate the
camera along the z axis. With a perspective projection that looks
similar to narrowing the field of view.
Of course with an orthographic camera moving the camera closer/farther
from the scene has no effect (ignoring near/far clipping), so it always
looks the same. To get a zoom effect you need to make the viewing volume
smaller (so that a smaller world volume is projected to the same screen
size -> zoom) by changing the ortho camera's horizontalSize,
verticalSize fields. For a perspective camera you'd change the field of
view instead.
Cheers,
Carsten
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