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

[metanet s. <met...@ya...>]

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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