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Cut operation - right vs. left #150

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DaveInCaz opened this issue Jan 31, 2018 · 5 comments
Open

Cut operation - right vs. left #150

DaveInCaz opened this issue Jan 31, 2018 · 5 comments
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@DaveInCaz
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In the documentation on this page:
http://esri.github.io/geometry-api-java/doc/Cut.html

It says:

"All left cuts will be grouped together in the first geometry. Right cuts and coincident cuts are grouped in the second geometry."

What do left and right mean in this context?

Thanks

@jgravois
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jgravois commented Jan 31, 2018

i could be wrong, but i always assumed right and left referred to the cardinality as perceived using the bearing of the cutting geometry if it were to animate and grow dynamically from its first vertex to its last to do the cutting.
2018-01-31 09 40 33

@stolstov
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At the location of the cut, the left is to the left of the tangent vector of the the cutter segment and the right is to the right of it. For the tangent vector if you direct your right hand index finger in the direction of the tangent your thumb will point to the left (keep your palm faced down to the 2D plane).

@jgravois
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@DaveInCaz
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Thanks for the clarifications. IMO this would be good info to expand on in the Wiki page. The detail that a polyline has a direction was not evident to a newbie like me. Also I had missed the distinction that the CUT operation's second argument is a polyline, wheras most others take a GEOMETRY.

@jgravois
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we actually host that document in the gh-pages branch of this repository. a pull request with the improvements you mentioned would be welcome.

<p>All left cuts will be grouped together in the first geometry. Right cuts and coincident cuts are grouped
in the second geometry. Each undefined cut along with any uncut parts are output as separate geometries. If there were no cuts, the cursor will return no geometry. If the left
or right cut does not exist, the returned geometry will be empty for this type of cut.</p>
<p>An undefined cut will only be produced if a left or right cut was produced and there was a part left over after cutting or a cut is bounded to the left and right of the cutter.</p>

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