Hi Frank,
Good detective work. I hadn't thought about this tiny little
"optimization" in the updateCalculatedNearFar. This optimization only
makes sense of perspective projections, and if fact could probably be
safely removed completely for all types of projection matrices.
Could you comment out the lines:
if (d_far<0.0)
{
// whole object behind the eye point so discard
return false;
}
>From CullVisitor::updateCalculatedNearFar and see how you get on. If
that works fine then we'll need to look at a fix in svn.
Robert.
On Fri, Nov 14, 2008 at 9:05 PM, <[EMAIL PROTECTED]> wrote:
> osgUtil/CullVisitor.cpp line 644-645:
>
> // whole object behind the eye point so discard
> return false;
>
> Perhaps its not called "culling" in this case but my code hits this return
> statement and as a result, the drawable is not added to the StateGraphList in
> RenderBin. OpenGL is never given a chance to clip.
>
> Frank
>
> On Fri, Nov 14, 2008 at 08:22:31PM +0000, Robert Osfield wrote:
>> Hi Frank,
>>
>> If culling is switched off then culling is off, the eye point will
>> make no difference.
>>
>> What difference you moving the eye point will be in the clipping due
>> to the position of near/far plane.
>>
>> Robert.
>>
>> On Fri, Nov 14, 2008 at 8:09 PM, <[EMAIL PROTECTED]> wrote:
>> > I think I figured it out. It looks like even with culling turned off,
>> > nodes that are behind the "eye point" are culled. See
>> > osgUtil/CullVisitor.cpp line 645.
>> >
>> > I now calculate the view matrix as follows.
>> >
>> > osg::Matrixd matrix = osg::Matrixd::translate( -center );
>> > matrix.postMultRotate( osg::Quat( PI, osg::Vec3d( 1.0, 0.0, 0.0 ) ) );
>> > matrix.postMultTranslate( osg::Vec3d( 0.0, 0.0, -0.5 ) );
>> >
>> > Adding the last translation transform to push the nodes away from the
>> > "eye point" made the problem go away.
>> >
>> > Is this a bug?
>> >
>> > Frank
>> >
>> > On Thu, Nov 13, 2008 at 11:38:14AM -0500, [EMAIL PROTECTED] wrote:
>> >> Hi Robert,
>> >>
>> >> Thanks for the quick response. That was a good suggestion. However it
>> >> looks like that is not the problem. All of my nodes live on the z=0.0
>> >> plane and my projection matrix is
>> >>
>> >> osg::Matrixd::ortho( -aspectRatio, aspectRatio, -1.0, 1.0, -1.0, 1.0 )
>> >>
>> >> I have attached a small code sample that exhibits the problem.
>> >>
>> >> Frank
>> >>
>> >> On Thu, Nov 13, 2008 at 04:24:37PM +0000, Robert Osfield wrote:
>> >> > Hi Frank,
>> >> >
>> >> > My best guess is that your projection matrix isn't wide enough to
>> >> > encompass your scene and near/far clipping is clipping out the
>> >> > fragments. This may well look like culling, often users do mistake
>> >> > clipping with culling so chase up the wrong part of the pipeline.
>> >> >
>> >> > Robert.
>> >> >
>> >> > On Thu, Nov 13, 2008 at 4:18 PM, <[EMAIL PROTECTED]> wrote:
>> >> > > Greetings osg community,
>> >> > >
>> >> > > I'm have written a custom MatrixManipulator for a 2D scene and I am
>> >> > > experiencing a strange problem. As I pan and zoom around, some of the
>> >> > > nodes in the scene disappear abruptly as if they are being culled
>> >> > > inappropriately. However, disabling culling has no effect.
>> >> > >
>> >> > > The behavior is erratic and unpredictable which smells to me like I'm
>> >> > > on
>> >> > > the border of a floating point inequality. I have discovered two ways
>> >> > > that seem to make the problem go away.
>> >> > >
>> >> > > One:
>> >> > >
>> >> > > One of the transformations I use to construct the view matrix is
>> >> > >
>> >> > > osg::Matrixd::rotate( osg::Quat( PI, osg::Vec3d( 1.0, 0.0, 0.0 ) )
>> >> > > )
>> >> > >
>> >> > > If I replace that with
>> >> > >
>> >> > > osg::Matrixd::scale( osg::Vec3d( 1.0, -1.0, 1.0 ) )
>> >> > >
>> >> > > the problem seems to go away.
>> >> > >
>> >> > > Two:
>> >> > >
>> >> > > All of the nodes in my seen that exhibit this problem have a 2D
>> >> > > bounding box. i.e.
>> >> > >
>> >> > > osg::BoundingBox const & bb = pGeode->getBoundingBox();
>> >> > > assert( bb.zMax() - bb.zMin() < 1e-5 );
>> >> > >
>> >> > > If I give the nodes some depth so that the above assert would fail,
>> >> > > the problem seems to go away.
>> >> > >
>> >> > > I suspect that these are not actual solutions. In any case, I would
>> >> > > like
>> >> > > to understand what is happening under the covers. Any ideas?
>> >> > >
>> >> > > Frank
>> >> > >
>> >> > > _______________________________________________
>> >> > > osg-users mailing list
>> >> > > [email protected]
>> >> > > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>> >> > >
>> >> > _______________________________________________
>> >> > osg-users mailing list
>> >> > [email protected]
>> >> > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>> >
>> >>
>> >> #include <osg/Geode>
>> >> #include <osg/Geometry>
>> >> #include <osgViewer/Viewer>
>> >>
>> >> #include <iostream>
>> >> #include <cassert>
>> >>
>> >> osg::ref_ptr< osg::Node > CreateGraph()
>> >> {
>> >> osg::ref_ptr< osg::Geode > pGeode = new osg::Geode();
>> >> osg::ref_ptr< osg::Geometry > pGeometry = new osg::Geometry();
>> >> pGeode->addDrawable( pGeometry.get() );
>> >>
>> >> // Vertices
>> >> osg::ref_ptr< osg::Vec3Array > pVerts = new osg::Vec3Array( 4 );
>> >> (*pVerts)[ 0 ] = osg::Vec3( 0.0, 0.0, 0.0 );
>> >> (*pVerts)[ 1 ] = osg::Vec3( 1.0, 0.0, 0.0 );
>> >> (*pVerts)[ 2 ] = osg::Vec3( 1.0, 1.0, 0.0 );
>> >> (*pVerts)[ 3 ] = osg::Vec3( 0.0, 1.0, 0.0 ); // dosen't work
>> >> //(*pVerts)[ 3 ] = osg::Vec3( 0.0, 1.0, 0.1 ); // works as expected
>> >> pGeometry->setVertexArray( pVerts.get() );
>> >>
>> >> pGeometry->addPrimitiveSet( new osg::DrawArrays(
>> >> osg::PrimitiveSet::QUADS, 0, 4 ) );
>> >>
>> >> osg::ref_ptr< osg::Vec4Array > pColors = new osg::Vec4Array( 4 );
>> >> (*pColors)[ 0 ] = osg::Vec4( 1.0f, 1.0f, 1.0f, 1.0f );
>> >> (*pColors)[ 1 ] = osg::Vec4( 1.0f, 0.0f, 0.0f, 1.0f );
>> >> (*pColors)[ 2 ] = osg::Vec4( 0.0f, 1.0f, 0.0f, 1.0f );
>> >> (*pColors)[ 3 ] = osg::Vec4( 0.0f, 0.0f, 1.0f, 1.0f );
>> >> pGeometry->setColorArray( pColors.get() );
>> >> pGeometry->setColorBinding( osg::Geometry::BIND_PER_VERTEX );
>> >>
>> >> osg::ref_ptr< osg::StateSet > pState = pGeode->getOrCreateStateSet();
>> >> pState->setMode( GL_LIGHTING, osg::StateAttribute::OFF );
>> >>
>> >> osg::BoundingBox const & bb = pGeode->getBoundingBox();
>> >> std::cout
>> >> << "BoundingBox = ("
>> >> << bb.xMin() << ","
>> >> << bb.yMin() << ","
>> >> << bb.zMin() << ","
>> >> << bb.xMax() << ","
>> >> << bb.yMax() << ","
>> >> << bb.zMax() << ")"
>> >> << std::endl;
>> >>
>> >> return pGeode.get();
>> >> }
>> >>
>> >> int main( int argc, char * argv[] )
>> >> {
>> >> int const x = 100;
>> >> int const y = 100;
>> >> int const w = 800;
>> >> int const h = 800;
>> >>
>> >> osg::ref_ptr< osg::GraphicsContext::Traits > pTraits = new
>> >> osg::GraphicsContext::Traits();
>> >> pTraits->x = x;
>> >> pTraits->y = y;
>> >> pTraits->width = w;
>> >> pTraits->height = h;
>> >> pTraits->windowDecoration = true;
>> >> pTraits->doubleBuffer = true;
>> >> pTraits->sharedContext = 0;
>> >>
>> >> osg::ref_ptr< osg::GraphicsContext > pContext =
>> >> osg::GraphicsContext::createGraphicsContext( pTraits.get() );
>> >> assert( pContext.valid() );
>> >>
>> >> osgViewer::Viewer viewer;
>> >>
>> >> viewer.getCamera()->setGraphicsContext( pContext.get() );
>> >> viewer.getCamera()->setClearColor( osg::Vec4( 0.0, 0.0, 0.0, 1.0 ) );
>> >> viewer.getCamera()->setViewport( new osg::Viewport( 0, 0, w, h ) );
>> >> viewer.getCamera()->setGraphicsContext( pContext.get() );
>> >> viewer.getCamera()->setCullingMode( osg::CullSettings::NO_CULLING );
>> >>
>> >> double const aspectRatio = double(w)/double(h);
>> >> //osg::Matrixd ortho = osg::Matrixd::ortho2D( -aspectRatio,
>> >> aspectRatio, -1.0, 1.0 );
>> >> osg::Matrixd ortho = osg::Matrixd::ortho( -aspectRatio, aspectRatio,
>> >> -1.0, 1.0, -1.0, 1.0 );
>> >> viewer.getCamera()->setProjectionMatrix( ortho );
>> >>
>> >> osg::ref_ptr< osg::Node > pGraph = CreateGraph();
>> >>
>> >> viewer.setSceneData( pGraph );
>> >>
>> >> viewer.realize();
>> >>
>> >> int n = 0;
>> >> int const N = 4000; // adjust for your computer speed
>> >> osg::Vec3d const initialCenter( 0.5, 0.5, 0.0 );
>> >>
>> >> while ( !viewer.done() )
>> >> {
>> >> n = ( n + 1 ) % N;
>> >> double d = -double(n)/double(N);
>> >>
>> >> osg::Vec3d center = initialCenter + osg::Vec3d( 0.0, d, 0.0 );
>> >> //std::cout
>> >> // << "center = ("
>> >> // << center[0] << ","
>> >> // << center[1] << ","
>> >> // << center[2] << ")"
>> >> // << std::endl;
>> >>
>> >> osg::Matrixd matrix = osg::Matrixd::translate( -center );
>> >>
>> >> // doesn't work
>> >> double const PI = 3.14159265;
>> >> matrix.postMultRotate( osg::Quat( PI, osg::Vec3d( 1.0, 0.0, 0.0 ) ) );
>> >>
>> >> // works as expected, but left handed coordinate system is not desired
>> >> //matrix.postMultScale( osg::Vec3d( 1.0, -1.0, 1.0 ) );
>> >>
>> >> viewer.getCamera()->setViewMatrix( matrix );
>> >>
>> >> viewer.frame();
>> >> }
>> >>
>> >> return 0;
>> >> }
>> >>
>> >
>> >> _______________________________________________
>> >> osg-users mailing list
>> >> [email protected]
>> >> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>> >
>> > _______________________________________________
>> > osg-users mailing list
>> > [email protected]
>> > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>> >
>> _______________________________________________
>> osg-users mailing list
>> [email protected]
>> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
> _______________________________________________
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>
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