Hi, i finally got to cast some rays with my ray-casting application and i found out the perforamce is terribly low. i am not sure how fast the intersections should be counted, but i am pretty sure that an image 160x120 pixels (which is 19200 points) should be computed in less than 5.5 seconds ... which is the time i am getting when measuring.
i literally copied the part of the osgintersection example that is using the intersectorGroup. i am using the intersectionGroup and intersectionVisitor. Code: osgUtil::LineSegmentIntersector* intersector = new osgUtil::LineSegmentIntersector(osgUtil::LineSegmentIntersector::WINDOW, osg::Vec3(x, y, 0), osg::Vec3(x, y, 1)); intersectorGroup->addIntersector(intersector); this way i add intersectors to the group for each pixel of my window. this way i try to compute the intersections and measure time Code: osgUtil::IntersectionVisitor intersectionVisitor(intersectorGroup.get()); intersectionVisitor.setUseKdTreeWhenAvailable(true); osg::Timer_t startTick = osg::Timer::instance()->tick(); osg::Camera *cam = _wm->getSceneView()->getCamera(); cam->accept(intersectionVisitor); osg::Timer_t endTick = osg::Timer::instance()->tick(); std::cout << "Frame in " << osg::Timer::instance()->delta_s(startTick, endTick) << " sec." << std::endl; the time varies from 4.9 to 6 seconds for 160x120 pixel image, for 320x240 the time increases 4 times to roughly 22 seconds ... though i am using a notebook it is NOT any 86286 computer :) this way i won't be able to compute full screen app window in reasonable time :( i tried the built-in KdTree support by calling Code: osgDB::Registry::instance()->setBuildKdTreesHint(osgDB::ReaderWriter::Options::BUILD_KDTREES); as the first command in my main() function. As i didn't record any changes in the computing time, i even tried running the KdTreeBuilder on my loaded model "manually" Code: osg::KdTreeBuilder *kdtb = new osg::KdTreeBuilder; loadedModel->accept(*kdtb); still with NO preformance change. And by NO i mean NOthing, i am getting the same runing time. i also tried limiting the amount o intersections by setting the intersection limit for each intersector calling Code: intersector->setIntersectionLimit(osgUtil::Intersector::LIMIT_NEAREST); in the loop that creates one for every pixel of the window (the first code snippet in this post). only the LIMIT_ONE option decreased the computing time by roughly 0.3 seconds (which is still unacceptable), but the result i got was not accurate. what am i doing wrong? why are the Kd-Trees not working properly? the documentation says the performance should improve from tens to thousands times. then why not for me? Thank you for any tips that may help me. Andrey ------------------ Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=44655#44655 _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
