Hi This can happen for at least a couple of reasons
1:) Typically many people do not take notice of the RGB value of their transparent images and typically leave that white, which means the white RGB of transparent pixel blends with the opaque color and you see the halo effect, the simple fix for this one is to make the RGB value of the transparent pixel use an average colour to match the opaque ( greenish in this case) in your favorite Image editing package 2:) The Harder problem which can be seen as well as (1) is a sorting problem, All real-time scene graphs such as OSG/VEGAPRIEM/ Old Performer, sort at the geometry node level and not at an individual triangle level due to performance related reasons. So if you have many transparent primitives in a node then how basically draw in the order they are defines and depending on your view angle you will see such things a halos and punch through. a) What can you do, remodel how you create your geometry and only have single trees in each node ( not the most efficient) which will help alleviate the problem not necessarily fully stop it. b) Ensure that geometry nodes that have transparency do not overlap with other nodes because they sorting will typically fail for many view angles etc. c) You could override the actually draw of the primitives and sort by triangles depending on the view ( not recommended) d) You could create your own Draw bin and manually sort the nodes there as long they don't overlap but (b) would negate this Search the net for much more answers this has been discussed by myself and others many time over the years on the Performer lists, Vega list and here on the OSG lists, this is an old problem that will be around for a while until for 2, until the hardware gets fast enough to be able to allow us sort down to the primitive and fragment level and still maintain the frame rates we require for real-time simulation ____________________________________________________________________________ __ Gordon Tomlinson gor...@gordontomlinson.com IM: gordon3db...@3dscenegraph.com www.vis-sim.com www.gordontomlinson.com ____________________________________________________________________________ __ -----Original Message----- From: osg-users-boun...@lists.openscenegraph.org [mailto:osg-users-boun...@lists.openscenegraph.org] On Behalf Of LAO Wenhao Sent: Thursday, February 04, 2010 10:15 PM To: osg-users@lists.openscenegraph.org Subject: [osg-users] Why the blue or white edges are appeard when we use transparent textures? Hi, Why transparent edges are appeard when we use transparent textures? For example, in the osgforest example program, when a billboard tree is closer to another billbard tree, we will find a transparent edge in the front tree. We should see the back tree from the edge, but we see the ground. In the mode of "quads" or "osg::MatrixTransforms", these edges are even more apparent. Please see the picture.:( Thank you! Cheers, laowenhao ------------------ Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=23707#23707 Attachments: http://forum.openscenegraph.org//files/question_458.jpg _______________________________________________ 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
