Thanks All, exactly what i am looking for some days, why i have to use a negative PolygonOffset. But i still not found the problem. may i did a bad mistake in the code. i would like doing a review and of the presented code. may there is a z-flip inside what would be really bad. i don't know yet what's going wrong.
/adegli 2007/9/28, Terry Welsh <[EMAIL PROTECTED]>: > > I can't say what the problem is, but I doubt it is PolygonOffset. On > my own PSSM implementation and other simpler shadows that I have done > everything works well with factor = 1.1 and units = 4.0. These > numbers come straight out of this document: > http://www1.cs.columbia.edu/~ravir/6160/papers/shadowmaps.ppt > > Numbers as large as 10.0/20.0 really shouldn't be necessary, and I've > never heard of using negative numbers for PolygonOffset. That's a new > one on me. Anyway, I believe the problem lies somewhere other than > PolygonOffset. > -- > Terry Welsh - mogumbo 'at' gmail.com > www.reallyslick.com | www.mogumbo.com > > > Message: 8 > > Date: Thu, 27 Sep 2007 13:41:51 +0100 > > From: "Robert Osfield" <[EMAIL PROTECTED]> > > Subject: Re: [osg-users] ParallelSplitShadowMap .... > > To: "OpenSceneGraph Users" <osg-users@lists.openscenegraph.org> > > Message-ID: > > <[EMAIL PROTECTED]> > > Content-Type: text/plain; charset=ISO-8859-1 > > > > Thanks Adrian, > > > > Changes now merged and submitted to SVN. > > > > Visual quality is better with the suggested options in the README but > > still not great, in particular I loose shadows when near to objects > > and at shallow angles to the surfaces under shadow. I've played > > around with the polygonoffset and found that changing units makes no > > difference for the models/views I've tested, but factor to to 4 or 5 > > seems sufficient to avoid the z fighting. The values you've chosen > > for NVidia look excessive. > > > > I am beginning to wonder about the value of using PolygonOffset in > > this context, its just not reliable enough across hardware. > > Alternatives to using PolygonOffset are tweaking the depth range via > > osg::Depth or via a small tweak to the projection matrix. Replacing > > osg::PolygonOffset by osg::Depth might well be a useful thing to try. > > > > Robert. > > > > On 9/26/07, Adrian Egli <[EMAIL PROTECTED]> wrote: > > > Hi Robert, > > > > > > please update the PSSM, i did some bug fixes and added new features to > move > > > the camera virtual against the view direction by applaying a simple > distance > > > factor (a), which is calculated camera eye - camera center distance. > and we > > > can move the "light camera" against the light direction (b). > > > > > > (a) some objects behind the camera can cast shadow > > > (b) object aboive the camera can cast shadow > > > > > > then i fixed the shadow map orientation, now screen x coordinate > alinged > > > which improve the quality > > > > > > /adegli > > > > > > -- > > > ******************************************** > > > Adrian Egli > > > _______________________________________________ > > > osg-users mailing list > > > osg-users@lists.openscenegraph.org > > > > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > > > > _______________________________________________ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > -- ******************************************** Adrian Egli
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