[osg-users] LineOfSight intersection returning geometry

Robert Osfield robert.osfield at gmail.com
Fri Jan 22 00:02:00 PST 2016

Hi Tony,

On 22 January 2016 at 02:31, Tony Vasile <minghia at gmail.com> wrote:
> By the way what are the following fields in osgUtil::LineSegmentIntersector::Intersection :
> double                          ratio;
>             osg::NodePath                   nodePath;
>             osg::ref_ptr<osg::Drawable>     drawable;
>             osg::ref_ptr<osg::RefMatrix>    matrix;
>             osg::Vec3d                      localIntersectionPoint;
>             osg::Vec3                       localIntersectionNormal;
>             IndexList                       indexList;
>             RatioList                       ratioList;
>             unsigned int                    primitiveIndex;
> Things like the nodePath, drawable, localIntersectionPoint, and  the localIntersectionNormal, I can work out what the are. But what are the ratio, ratioList, primitiveIndex, and the matrix? Is the matrix a transformation matrix?

The IndexList contains the list of vertex indices of the primitive
that has been intersected, and the RatioList contains the weighting of
those vertices which when added together with their ratios gives the
intersection point.  This allows you to compute things like texture
coordinates, colours etc.  The primitiveIndex is the primitive number
into the geometry that the intersected primitive lies.  The matrix is
the accumulated transformation matrix that takes the local coordinate
point into coordinate frame of the root of the intersection traversal.

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