Hi Simon, The LineSegmentIntersector records the indices of the vertices of the primitive that has been hit. The LineSegmentIntersector::Intersection::indexList and ratioList provide the indices and barycentric coords.
Robert. On Tue, Sep 2, 2008 at 8:54 AM, Simon Notheis <[EMAIL PROTECTED]> wrote: > Hi everyone, > > I want to use mouse events to pick an object of the 3D scene. Instead of > working with the intersection point, I want to find the nearest vertex > or edge of the polygon that was hit. > Until now I used code similar to the following one: > > // Get the hitlist by using osg::Viewer::computeIntersection(...) > const osgUtil::LineSegmentIntersector::Intersection& > intersection = *(hitlist.begin()) > osg::Geometry* geometry = intersection.drawable->asGeometry() > > Then i used intersection.indexList and the geometry's VertexArray to > iterate through all vertices to find the closest vertex (vx) wrt the > intersection point. > Then I calculated the angles between vx and the both neighbouring > vertices in the indexList to determine which one belongs to the closest > edge. Finally, the nodePath gave me the local=>world transformation. > > All of that only worked because we had some bad code to load/convert our > own scene format into OSG. This code generated seperate triangles or > quads, so actually I always hit a polygon with 3 or 4 vertices, what > made it easy to determinie the neighbours of vx. > > Now that we're using some optimization steps (e.g. triangle strips), I > can't use the above code (e.g. the indexList is empty). I tried to use > the geometry's IndexArray instead, but the problem is that without > knowing the exact primitive type, it is hard to determine which vertices > are the neighbouring ones to find the edge. E.g. in case of an triangle > strip I would have to check the last 2 and next 2 vertices in the > index/vertex list. Also the code won't work if the drawable can't be > cast to a Geometry. > > So my question is, if there's a more easy or flexible way to determine > the closest vertex and edge of the intersected polygon/primitve? > > Looking forward to your ideas or solutions, if something similar was > already discussed here..... > > Simon > > _______________________________________________ > 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
