Simple 2D geometric primitives on top of euclid.
This crate is reexported in [lyon](https://docs.rs/lyon/).
# Overview.
This crate implements some of the maths to work with:
- lines and line segments,
- quadratic and cubic bézier curves,
- elliptic arcs,
- triangles.
# Flattening
Flattening is the action of approximating a curve with a succession of line segments.
The flattening algorithm implemented in this crate is based on the paper
[Fast, Precise Flattening of Cubic Bézier Segment Offset Curves](http://cis.usouthal.edu/~hain/general/Publications/Bezier/Bezier%20Offset%20Curves.pdf).
It tends to produce a better approximations than the usual recursive subdivision approach (or
in other words, it generates less segments for a given tolerance threshold).
The tolerance threshold taken as input by the flattening algorithms corresponds
to the maximum distance between the curve and its linear approximation.
The smaller the tolerance is, the more precise the approximation and the more segments
are generated. This value is typically chosen in function of the zoom level.
The figure above shows a close up on a curve (the dotted line) and its linear
approximation (the black segments). The tolerance threshold is represented by
the light green area and the orange arrow.