Guys,
I need to check whether a point falls within an arbitrary polygon.
This is in the context of another tool, and J will be a pre/post-processor.
The other tool allows it to check whether a point falls
within a given rectangle with great speed. However, it cannot efficient
determine containment for an arbitrary polygon.
So I'm considering putting a bounding box (circumscribed rectangle) around the
polygon, and maybe another one inside the polygon
(inscribed rectangle), using the tool to check those, and then, depending on
the results, using J to determine if the point is truly
within the polygon.
If I take that approach, I would need a few things:
(1) A way to represent polygons in J (an Nx2 array
of vertices?)
(2) A verb whose input is a polygon and whose output is the
minimum bounding rectangle around that polygon and/or
the maximum inscribed rectangle in that polygon.
The rectangle be represented like any other polygon,
i.e. (1).
(3) Some post-processing code that will be called when
the fast utility determines if the point is in the
outer rectangle rectangle and/or if the point is
outside the inner rectangle. The inputs is the
polygon and the points, and the output is a boolean
per point, which indicates whether the point is
"truly" in the polygon (because the outer rectangle
could contain the point, yet the polygon not, and the
inner rectangle could exclude the point, yet the
polygon could still contain it).
Can someone suggest some approaches?
-Dan
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