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January 2022

13 participants
12 discussions

Error with geometry buffer?
by KL 10 Jan '22

10 Jan '22

Hi, Boost Geometry 1.78, linux Â I was getting bad results with my calculations so I decided to narrow down the implementation up to the point I got the following problematic code: Â typedef boost::geometry::model::point <double, 2, boost::geometry::cs::cartesian> Vector2d; Â int main (){ Â Â Â Â Â Â Â Â multi_polygon <polygon <Vector2d> > mp; Â Â Â Â Â Â Â Â /*{ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â polygon <Vector2d> poly; Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â poly.outer().push_back( {0, 0} ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â poly.outer().push_back( {0, 4} ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â poly.outer().push_back( {4, 4} ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â poly.outer().push_back( {4, 0} ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â correct( poly ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â mp.push_back(poly); Â Â Â Â Â Â Â }*/ Â Â Â Â Â Â Â { Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â polygon <Vector2d> poly; Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â poly.outer().push_back( {10, -1} ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â poly.outer().push_back( {14, -1} ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â poly.outer().push_back( {10, -2} ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â poly.outer().push_back( {14, -2}Â ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â correct( poly ); Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â mp.push_back(poly); Â Â Â Â Â Â Â } Â Â Â Â Â Â Â Â Â boost::geometry::strategy::buffer::join_miter join_strategy; Â Â Â Â Â Â Â boost::geometry::strategy::buffer::end_flat end_strategy; Â Â Â Â Â Â Â boost::geometry::strategy::buffer::side_straight side_strategy; Â Â Â Â Â Â Â boost::geometry::strategy::buffer::point_square point_strategy; Â Â Â Â Â Â Â Â boost::geometry::strategy::buffer::distance_symmetric <double> distance_strategy( 2 ); Â Â Â Â Â Â Â boost::geometry::model::multi_polygon <polygon <Vector2d> > result; Â Â Â Â Â Â Â Â boost::geometry::buffer( mp, result, distance_strategy, side_strategy, join_strategy, end_strategy, point_strategy ); Â Â Â Â Â Â Â Â cout << dsv( result ) << endl; Â Â Â Â Â Â Â Â return 0; Â } Â and the result I get is: ((((13.7169, -3.13232), (13.5149, -3.94029), (12, -3.56155), (10.4851, -3.94029), (10.2831, -3.13232), (9.51493, -2.94029), (0.0749244, 0.221833), (10, 1), (14, 1), (23.9251, 0.221833), (14.4851, -2.94029), (13.7169, -3.13232)))) Â Notice the two points: (0.0749244, 0.221833) and (23.9251, 0.221833) Â I have multiple complex (concave) shapes which behave worse than that simple rectangle. But it is a starting point here. Â Did I do something wrong? I need to get my job done, any alternative or helping code massaging ? Â Thanks --Â MKL Â

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[ASIO] Need help reading the documentation
by Andrzej Krzemienski 01 Jan '22

01 Jan '22

Hi Everyone, I need some help in reading the ASIO docs. I am looking at the following example from the docs https://www.boost.org/doc/libs/1_78_0/doc/html/boost_asio/example/cpp17/cor… It calls one of the overloads of async_write in line co_await async_write(socket, boost::asio::buffer(data, n), use_awaitable); The reference section lists eight overloads: https://www.boost.org/doc/libs/1_78_0/doc/html/boost_asio/reference/async_w… But it is still impossible for me to figure out which one it is. `use_awaitable` is documented as "completion token" in https://www.boost.org/doc/libs/1_78_0/doc/html/boost_asio/reference/use_awa… There is some mention of completion token at https://www.boost.org/doc/libs/1_78_0/doc/html/boost_asio/reference/asynchr… So I would expect the name `CompletionToken` to appear in the documentation of `async_write`. Am I missing something? Regards, &rzej;

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