Hi Michele, I had a similar problem with intersecting polygons.
I fixed it by editing the model. First, I broke up the polygon so that no polygon intersected. This makes it so the depth sort will work for each polygon (ie. You don't have to depth sort pixels!). Then, I strategically placed group nodes above polygons, so that the groups never overlap. What this does, in affect, is really start sorting by polygon. I'm not sure if this is viable for you? Are you dynamically intersecting objects? In any case, adding more groups should improve the depth tests. If you can't modify the model, you could try to write a node visitor that inserts a group node above each polygon. I'm not sure how difficult that would be, though. I think it would be great to add the option of polygon depth sorting to OSG, but I don't know what affect that would have on performance? -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Michele Bosi Sent: Wednesday, September 05, 2007 6:05 PM To: [email protected] Subject: [osg-users] Polygon sorting Hello, I need to sort the polygons of my meshes in order to obtain decent transparencies for complex autointerstecting objects like 3d isosurfaces. I figured out that a very raw way to do so would be to subclass Viewer, reimplement frame(), and from there getting the viewMatrix and sorting my poligons based on their distance from the viewer (having disabled display list support for the node). The actual sorting would be done on the list of indices (osg::DrawElementsUInt) since I use indexed triangles. Since to get correct results I also have to take into account the transformation applied to my Geometry I was wondering if there was a more "clever" way to do all this mess, maybe there are already mechanisms that inform my Geometry that is going to be drawn so that I can react sorting my polygons appropriately at the correct moment and accounting for the currently active transformations, something similar to the VTK/pipeline system. Any idea? Regards, Mike _______________________________________________ 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
