Wasn't it TinyGrasshopper who wrote:
>You could also do rough checks to narrow down the possible polygons
>the point could be in (and therefore what polygons need to be tested
>with the full algorithm) by testing whether the point is within the
>bounds of each polygon too (since google provides a function to easily
>get the bounds).
>
>Performance would either go up (if the bounds are all precomputed when
>the polygons are loaded) or down (if it has to compute the bounds by
>iterating the points) :).

Here's two examples that are identical except that the second one
performs bounds checks before performing the polygon test.
  http://econym.org.uk/gmap/example_states2.htm
  http://econym.org.uk/gmap/example_states3.htm

I compute the bounds once, then store the info as a Property of the
polygon. The code checks the states in alphabetical order, and jumps out
of the loop when it gets a hit, so clicking on Wyoming shows the biggest
speed difference.

This code was written before Google introduced clickable polygons.

-- 
http://econym.org.uk/gmap
The Blackpool Community Church Javascript Team


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