[osg-users] LineSegmentIntersector::intersect + performance

[Robert Osfield]

Hi Guy,

Just how many separate LineSegmentIntersection and  Drawables are you
trying to intersect with?

As for the creation or the Settings object on the heap, as it's a
local new/delete and operation within a single thread it is probably
safe to replace with an object on the stack.

Robert.
On Tue, 26 Jun 2018 at 19:06, Volckaert, Guy (CA - MTS)
<Guy.Volckaert at meggitt.com> wrote:
>
> Hi,
>
> I recently upgraded to the OSG v3.6.1 and I noticed that the new LineSegmentIntersector has changed significantly compared to v3.4.0. As I was reviewing the changes, I noticed that the LineSegmentIntersector now allocates an instance of LineSegmentIntersectorUtils::Settings every time the IntersectionVisitor intercepts a drawable.
>
> From a purely efficiency standpoint, I was wondering if we could do better. Intersection were relatively slow in the past and now it seems that we made even slower. That being said, I'm pretty sure there's a valid reason for why it was done this way. Before I look at alternative solutions, I was wondering if anyone could share for reasons.
>
> Below is a snip-it of the function:
>
> void LineSegmentIntersector::intersect(osgUtil::IntersectionVisitor& iv, osg::Drawable* drawable,
>                                        const osg::Vec3d& s, const osg::Vec3d& e)
> {
>     if (reachedLimit()) return;
>
>     osg::ref_ptr<LineSegmentIntersectorUtils::Settings> settings = new LineSegmentIntersectorUtils::Settings; ////// <<<<<<<<<< HERE <<<<<<<<<<<<
>     settings->_lineSegIntersector = this;
>     settings->_iv = &iv;
>     settings->_drawable = drawable;
>     settings->_limitOneIntersection = (_intersectionLimit == LIMIT_ONE_PER_DRAWABLE || _intersectionLimit == LIMIT_ONE);
>
>     osg::Geometry* geometry = drawable->asGeometry();
>     if (geometry)
>     {
>         settings->_vertices = dynamic_cast<osg::Vec3Array*>(geometry->getVertexArray());
>     }
>
>     osg::KdTree* kdTree = iv.getUseKdTreeWhenAvailable() ? dynamic_cast<osg::KdTree*>(drawable->getShape()) : 0;
>
>     if (getPrecisionHint()==USE_DOUBLE_CALCULATIONS)
>     {
>         osg::TemplatePrimitiveFunctor<LineSegmentIntersectorUtils::IntersectFunctor<osg::Vec3d, double> > intersector;
>         intersector.set(s,e, settings.get());
>
>         if (kdTree) kdTree->intersect(intersector, kdTree->getNode(0));
>         else drawable->accept(intersector);
>     }
>     else
>     {
>         osg::TemplatePrimitiveFunctor<LineSegmentIntersectorUtils::IntersectFunctor<osg::Vec3f, float> > intersector;
>         intersector.set(s,e, settings.get());
>
>         if (kdTree) kdTree->intersect(intersector, kdTree->getNode(0));
>         else drawable->accept(intersector);
>     }
> }
>
> Regards,
>
> Guy Volckaert, ing.
> Snr Software Engineer
>
> Meggitt Training Systems (Quebec) Inc.
> Systèmes d'entraînement Meggitt (Québec) Inc.
> 6140 Henri Bourassa West
> Montreal, Quebec, H4R 3A6
> Canada
>
> Tel: 1 (514) 339 9938 Ext 617
> Fax: 1 (514) 339 2641
> Cell: 1 (514) 928-5641
> email: guy.volckaert at meggitt.com
> url; www.meggitt.com
> skype: guy.volckaert
>
> Svp. Considérez l'environnement avant d'imprimer
> Please consider the environment before printing this e-mail.
>
>
> ________________________________
>
>
> This e-mail may contain proprietary information and/or copyright material. This e-mail is intended for the use of the addressee only. Any unauthorized use may be unlawful. If you receive this e-mail by mistake, please advise the sender immediately by using the reply facility in your e-mail software.
>
> Information contained in and/or attached to this document may be subject to export control regulations of the European Community, USA, or other countries. Each recipient of this document is responsible to ensure that usage and/or transfer of any information contained in this document complies with all relevant export control regulations. If you are in any doubt about the export control restrictions that apply to this information, please contact the sender immediately.
>
> Be aware that Meggitt may monitor incoming and outgoing e-mails to ensure compliance with the Meggitt IT Use policy.
>
> _______________________________________________
> osg-users mailing list
> osg-users at lists.openscenegraph.org
> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org