Hi, I was wondering. I want to implement some picking, however I don't want to pick the entire scene graph. Just a sub-tree.
I looked at osg::View::computeIntersections to try to replicate what it is doing. I have mimicked the code pretty much exactly, with one exception. Instead of having the camera accept the IntersectionVisitor, I have the root of my sub-tree accept it. However, it doesn't seem to be working. The LineSegmentIntersector has zero intersections. However, if I switch to having the camera accept the IntersectionVisitor, then I get all of the intersections I'm expecting (and many that I don't want). I tried a different approach: instead of having the sub-tree root accept the Visitor, have the camera accept it, since I know that works. However, give the root of my sub-tree a special nodemask so that the Visitor will affect it and ignore the others (the descendant nodes of this sub-tree root all have node masks of 0xffffffff so they will allow anything to traverse, but since the roots of the sub-trees that I'm interested in all have node masks of 0x1, this could work). The problem is, now I have to make sure that the _parents_ of these sub-tree roots all have this special bit set, which they don't, and managing that could be a pain. I could just feed the Visitor to the camera, compute all intersections, and then try to suss out which node sub-trees were hit. This is sort of what I was doing before, but I found it to be a problem because our scene graph structure is not set up in a way that I can just look at a certain element in the NodePath to know what I hit. I write a fair amount of intelligence into it, and actually this is the way I _have_ been doing it, and I'm trying to move away from it because it's becoming unwieldy. I already have a list of the sub-tree roots that I care about, and I'd much rather just be able to ask one of these roots "Have you been picked?" Does anyone have any suggestions? If so, that would be a huge help. Meanwhile, I keep plugging ahead and see what I find. Maybe the camera node is doing something to the IntersectionVisitor that I should know about? I'll take a look at that next. Thank you! Cheers, Frank ------------------ Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=29535#29535 _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
