[osg-users] Camera vs Projection

Robert Osfield robert.osfield at gmail.com
Sun Mar 22 04:04:43 PDT 2009

Hi Guy,

On Sun, Mar 22, 2009 at 8:10 AM, Guy <guy at dvp.co.il> wrote:

>  While reading through the mailing list I read somewhere that
> osg::Projection is obsolete and replaced by osg::Camera that has much
> more functionality.
>  I thought that having another camera, means another pass of rendering,
> which is a quite difference since osg::projection only push the
> projection matrix, replace it and pop it at the end. Am I right?

An osg::Camera that has it's RenderOrder to NESTED will just set the project
and view matrices, it want clear any buffers and will nest all enclosed
sugraph within the current RenderStage.  This makes it pretty close to the
use of Projection node and MatrixTransform ndoe that used to have to be used

>  Another question about Camera and near-far plane computation. If a
> camera does calculate near far planes during the culling, but has
> somewhere underneath other cameras or projections, does these affect the
> near-far calculations? Does the near far planes that were calculated
> affect the other cameras/projections?

The computation of the near far is optional and controlled via the
ComputeNearFarMode.  When enabled the near far computation happens in the
cull traversal for the camera being traversed.

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