Hi Anders, Even with default settings the culling will be done with doubles, with any floats being cast into doubles before tests against the view frustum planes rather than from doubles down to floats.
I'm curious what makes you think the problem is culling. Could it be clipping? Could it be small feature culling? Robert, On 10 October 2012 13:43, Anders Backman <[email protected]> wrote: > Hi all. > > Using OSG 3.0.1 under windows. > > A problem that we have experienced now and then without understanding the > source of it, is that we get culling problems for scenes where objects are > rendered far from origo. > > > By default, OSG use float for representing bounding boxes, spheres etc. > I believe I comment on this quite a few years ago related to some other > project we were working on. So the support for double representation in BV:s > was added. > > However, we still seem to have problems. > > Assume you want to do some rendering using ECEF coordinates, where 0,0,0 is > at the center of the earth. > Then you might end up with values around 6371014 meters. This is obviously > not possible to represent in high enough precision for float. > > What we have been doing to avoid the culling problems is to explicitly use > an inverse matrix which brings the coordinates used for rendering down to > origo and multiply all transforms with this matrix. > > This give us problem, where in some specific camera views, some of the > rendered (long cylinders) are suddenly culled away, moving closer/away will > bring them back. I will try to reduce this to an OSG example... > > > What we would LIKE to do, is to have a MatrixTransform with this inverse > matrix. But this was not working before (with float BV:s), and even now with > the cmake settings below: > > > //Set to ON to build OpenSceneGraph with float BoundingBox instead > // of double. > OSG_USE_FLOAT_BOUNDINGBOX:BOOL=OFF > > //Set to ON to build OpenSceneGraph with float BoundingSphere instead > // of double. > OSG_USE_FLOAT_BOUNDINGSPHERE:BOOL=OFF > > //Set to ON to build OpenSceneGraph with float Matrix instead of > // double. > OSG_USE_FLOAT_MATRIX:BOOL=OFF > > //Set to ON to build OpenSceneGraph with float Plane instead of > // double. > OSG_USE_FLOAT_PLANE:BOOL=OFF > > > We still see culling problems. > However, I have not been able to break it down to a simple example > demonstrating THIS problem. > > But the example below sure show some problems where for some reason, the > coordinates are converted to float somewhere in the pipeline. Im using Vec3D > for representing the vertices, the inverse transform is in double precision. > Still, I get some weird rendering due to this. > > > Is there anyone else rendering objects far away from origo that have a > success-story to share? > > #define X_VAL 6371014 > > #include <osg/Geode> > #include <osg/Geometry> > #include <osg/Material> > #include <osg/Vec3> > #include <osg/MatrixTransform> > #include <osg/Texture2D> > #include <osg/PolygonStipple> > #include <osg/TriangleFunctor> > #include <osg/io_utils> > #include <osgDB/ReadFile> > #include <osgDB/WriteFile> > #include <osgGA/TrackballManipulator> > #include <osgViewer/Viewer> > #include <osg/Math> > #include <iostream> > > > > osg::Node* createScene() > { > // create the Geode (Geometry Node) to contain all our osg::Geometry > objects. > osg::Geode* geode = new osg::Geode(); > > > // create LINES > { > // create Geometry object to store all the vertices and lines primitive. > osg::Geometry* linesGeom = new osg::Geometry(); > > // this time we'll preallocate the vertex array to the size we > // need and then simple set them as array elements, 8 points > // makes 4 line segments. > osg::Vec3dArray* vertices = new osg::Vec3dArray(8); > (*vertices)[0].set(X_VAL-1.13704, -2.15188e-09, 0.40373); > (*vertices)[1].set(X_VAL-0.856897, -2.15188e-09, 0.531441); > (*vertices)[2].set(X_VAL-0.889855, -2.15188e-09, 0.444927); > (*vertices)[3].set(X_VAL-0.568518, -2.15188e-09, 0.40373); > (*vertices)[4].set(X_VAL-1.00933, -2.15188e-09, 0.370773); > (*vertices)[5].set(X_VAL-0.716827, -2.15188e-09, 0.292498); > (*vertices)[6].set(X_VAL-1.07936, 9.18133e-09, 0.317217); > (*vertices)[7].set(X_VAL-0.700348, 9.18133e-09, 0.362533); > > > // pass the created vertex array to the points geometry object. > linesGeom->setVertexArray(vertices); > > // set the colors as before, plus using the above > osg::Vec4Array* colors = new osg::Vec4Array; > colors->push_back(osg::Vec4(1.0f,1.0f,0.0f,1.0f)); > linesGeom->setColorArray(colors); > linesGeom->setColorBinding(osg::Geometry::BIND_OVERALL); > > // set the normal in the same way color. > osg::Vec3Array* normals = new osg::Vec3Array; > normals->push_back(osg::Vec3(0.0f,-1.0f,0.0f)); > linesGeom->setNormalArray(normals); > linesGeom->setNormalBinding(osg::Geometry::BIND_OVERALL); > > // This time we simply use primitive, and hardwire the number of coords > to use > // since we know up front, > linesGeom->addPrimitiveSet(new > osg::DrawArrays(osg::PrimitiveSet::LINES,0,8)); > > > // add the points geometry to the geode. > geode->addDrawable(linesGeom); > } > > return geode; > } > > int main(int, char **) > { > osg::Group *root = new osg::Group; > > osg::MatrixTransform *mt = new osg::MatrixTransform; > osg::Matrix m; > > root->addChild(mt); > > m.setTrans(-X_VAL, 0,0 ); > mt->setMatrix( m ); > > // create the model > > mt->addChild( createScene() ); > > osgViewer::Viewer viewer; > viewer.setUpViewInWindow( 0,0, 1280, 720); > > osgDB::writeNodeFile(*mt, "asd.osgx"); > > // add model to viewer. > viewer.setSceneData( root ); > > return viewer.run(); > } > > > Cheers, > Anders > > > -- > __________________________________________ > Anders Backman, HPC2N > 90187 Umeå University, Sweden > [email protected] http://www.hpc2n.umu.se > Cell: +46-70-392 64 67 > > _______________________________________________ > 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
