RE: Path algorithm

[paulbox]

If you have a way for a wet cell to decide if it's neighbor is a wet cell, 
then you could have a recursive function that has each wet cell return a list 
of its wet neighbors.  The algorithm could start in any wet cell and spread 
out until all wet cells who are somehow connected are a member of a common 
list.  This would not tell you how efficiently you could get from one to the 
other, just tell you that they are in the same "blotch".

If you're in a static landscape, you may wish to simply establish lists of 
connected cells in the beginning.  If this "membership list" has to be 
reassessed every time the fish make a query, you might think of a more 
efficient way to manage this.

If you need to determine the best path from one wet cell to another, there is 
a large body of literature in "least cost path" analysis.  I would be happy to 
provide some references if you're interested.


>===== Original Message From M Lang / S Railsback <address@hidden> =====
>I need an algorithm to see if you can get from one place in a Grid2D to
>another region of the grid.
>
>Say there are a patch of connected grid cells that are "safe" for my
>fish. The other cells are either wet or dry, and the fish can only move
>through wet cells. I need to determine for each wet cell whether or not
>there is a connection through the other wet cells to the "safe" patch.
>
>Does anyone have an efficient algorithm for this?
>
>Thanks
>
>Steve
>--
>address@hidden
>Lang, Railsback & Assoc.
>250 California Ave., Arcata CA 95521
>707-822-0453; Fax 822-1868
>
>Until July 1, 2001:
>       Los Alamos, NM
>       505-661-4258
>
>
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////////////////////////////////////////
// Paul Box
// Geography and Earth Resources
// Utah State University



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