Add docs for polygon functions

[DanRoscigno]

Add docs for PR #19257

closes #35341

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@nikitamikhaylov can you help with the descriptions for these functions? I am having a problem with the spherical functions, I do not understand how they work.

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[DanRoscigno]

Thanks so much @nikitamikhaylov. I will go back to the tests and add the rest of the examples and publish this, then add the docs to the source so that they can be maintained there and we have the same info in system.functions and in the published docs.

[DanRoscigno]

@nikitamikhaylov I need more help, please. Can you teach me how to read the code and determine the input params for polygonAreaSpherical()? It looks like several points and an int.

[nikitamikhaylov]

Oh, there is no easy way to determine the input params. From this line

ClickHouse/src/Functions/polygonArea.cpp

Line 52 in c5b5214

size_t getNumberOfArguments() const override

we understand that the input param count is 1. And from the name of the function we can say that the input param is Polygon, which in fact has type Array(Array(Tuple(Float64, Float64)))

[DanRoscigno]

Oh, there is no easy way to determine the input params. From this line

ClickHouse/src/Functions/polygonArea.cpp

Line 52 in c5b5214

size_t getNumberOfArguments() const override

we understand that the input param count is 1. And from the name of the function we can say that the input param is Polygon, which in fact has type Array(Array(Tuple(Float64, Float64)))

Thanks, I must have been losing my mind; when I was looking at the test, I could have sworn I saw a polygon and a single tuple as args, and I was trying to figure out why the extra tuple/point was needed. Thanks again for your help!

[nikitamikhaylov]

Some cheat sheet:

Point is Tuple(Float64, Float64)
Ring is Array(Tuple(Float64, Float64)) - Array of points in clockwise order (maybe counter-clockwise, I don't remember)
Polygon is Array(Array(Tuple(Float64, Float64))) - First array define an external border, others define holes inside.
MultiPolygon is Array(Array(Array(Tuple(Float64, Float64))))