2009/5/21 Matthias Gabriel <[email protected]>: > Hi, > today i wanted to build my own "LineSegmentIntersector" - well some kind > of... while doing this, i looked into the sourcecode of the > LineSegmentIntersector. There I saw, that the tests in > "LineSegmentIntersector::intersects(..)" refer to start and end point of the > lsi on the one hand, and to boundsphere.center()/radius() on the other hand. > But here is my Problem. Start and end- points are in world coordinates, > while the boundingsphere is in local coordinates...somewhere here in the > newsgroup a read, that boundingssphere only refers to their children.. > > I came to this problem, while implementing my own > Intersect-Bounding-Algorithms, where i get wrong results... Why is the > original LinesegmentIntersector working or: is it actually working? > > At which point am i missunderstanding this? > > Thanks für your Help, > MG
As you traverse the scene graph, you maintain a matrix stack in the same way that open gl does. Enter a transform, push your stack, multiply the transform into it. Leave a transform and pop your stack. Then when you want to do the intersection, you can either transform the bounding sphere into world coordinates or transform your pick ray into local coordinates. It's easier to transform the ray, but then you have to pay for a matrix invert. -- http://www.ssTk.co.uk _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
