The outline to offset.
OptionaldeltaHow far the outline moves, in model units: positive grows outer contours and shrinks holes, negative does the opposite.
OptionaljoinHow corners are treated: round, square, miter or bevel.
OptionalmiterFor miter joins, how far a corner may reach as a multiple of delta before it is squared
off; 2 is the smallest allowed.
OptionalcircularFor round joins, how many segments a full circle of rounding gets.
A cross-section and the offset settings for
crossSection.operations.offset.