[osg-users] Parameter "ratio" in osgUtil::LineSegmentIntersector::Intersection

Paul Melis paul at science.uva.nl
Tue Sep 30 00:29:02 PDT 2008


Andreas Goebel wrote:
> Hello,
>
> I need to sort out intersections that are very close to each other. So 
> I took a look at the LineSegmentIntersector::Intersection definition:
>
>            bool operator < (const Intersection& rhs) const { return 
> ratio < rhs.ratio; }
>
>            typedef std::vector<unsigned int>   IndexList;
>            typedef std::vector<double>         RatioList;
>
>            double                          ratio;
>
> and saw that there is a ratio-parameter for sorting.
>
> What is that ratio-parameter expressing? May I assume that points 
> which are very close to each other do have a ratio that is very close?
> I guess that the other direction is not true: Points with a close 
> ratio might be apart.
My impression so far has been that 'ratio' is the parameter more 
commonly named 't' when talking about a parametric line P, i.e.
P(t) = segment_start + t * (segment_end - segment_start)

Could be wrong though...
Paul
>
> So what I would do if my assumptions are true is first to test if an 
> intersection has a close ratio to the intersection before in the list. 
> If this is true, then I will test the distance.
>
> Regards,
>
> Andreas
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