Re: [Algorithms] Moving Segment vs Moving Point Intersection (2D)

[Jonathan B. <jo...@nu...>]

Right.  Of course.

I vow that next time I post something to gdalgorithms I am going to 
actually look at the equation and think about it.



metanet software wrote:
> hi,
> just in case anyone else is going to use this -- you actually can't 
> naively discard the later intersection, because the quadratic gives 
> you the intersection times of the _infinite_ line with the point. 
>
> if you're interested in the segment-vs-point intersections (as i was), 
> you have look at both roots to see if either represents an 
> intersection with the lineseg; sometimes the earlier intersection is 
> outside the lineseg, while the later one is in/on the lineseg.
>
> raigan
>
>
> */Nils Pipenbrinck <n.p...@cu...>/* wrote:
>
>     Dave Moore wrote:
>
>     >
>     > Small niggle: you get a quadratic equation in t not a linear one,
>     > right? There are cases where you get 2 crossings.
>
>
>     Yes, but you're usually interested in the intersection that happends
>     earliest. It's save to discard the greater one.
>
>     Nils
>
>
>
>
>
>
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