> "Samuel Benge" <stb### [at] hotmailcom> wrote:
>
>> scott <sco### [at] scottcom> wrote:
>>> ...or do it numerically by using the trace function. You could define
>>> one of the lines as a very thin cylinder, then do a trace from the start
>>> point of the 2nd line towards its end point.
>>
>> Or for more accuracy, make one line a plane. Use VPerp_To_Vector or
>> Point_At_Trans to align the plane along the line and translate it to one of its
>> endpoints. Then use trace(). I do that every time I need to find a line
>> intersection and it works perfectly. Also, using trace()'s fourth parameter
>> helps make sure you get an intersection: if the ray hits nothing (the normal is
>> <0, 0, 0>) then just reverse its direction.
>
> I guess this assumes that the two lines DO lie on the same plane.
>
> But wouldn't using trace() require essentially an infinite number of trace
> points, so that trace doesn't 'miss' the intersection? Or is it an iterative
> approach--i.e., when the returned trace point is 'close' to the target spot,
> then trace is used again, but restricted to that smaller vicinity (and so on)? I
> can see that working successfully, to a certain precision; but it doesn't seem
> possible to find the *exact* point of intersection (without infinite trace
> rays.) In a practical sense, though, an exact match might not be necessary.
>
>
>
>

A single trace call should be enough in most cases, at most two.
You call the trace from a point along one of the lines toward another 
point on that same line. You replace the second line by a thin cylinder.

Post a reply to this message