[osg-users] getDistanceToViewPoint not implemented in osgUtil::IntersectionVisitor

Robert Osfield robert.osfield at gmail.com
Thu Mar 19 07:19:49 PDT 2009


Hi Jason,

2009/3/19 Jason Beverage <jasonbeverage at gmail.com>

> Hi Robert,
>
> I was looking through CullVisitor and trying to get my head around the
> difference between the eye point and the viewpoint.  Is the viewpoint stack
> is used to deal with internal camera nodes then?  Then the "eye" point is
> the main camera's position while the "view" point would be used for
> currently executing camera node.  If you don't have any internal camera
> nodes, then would the eye point and the viewpoint be equivalent?
>

It's actually the other way around.  The eye point is the local cameras eye
point, while the viewpoint is the viewer's master camera's eye point,
normally they coincide, but in the case of RTT effects like shadows you will
generate the shadow from the light source center/direction while you'll
still want LOD calculation done against the viewer's eye point.

In the case of intersection testing you sometime want to use a dummy eye
point, such as by setting the "eye" point to the end of
LineSegmentIntersector, this can be done to make sure that LOD setting are
selected appropriate for your needs, same goes to billboard rotations.

Robert.
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