Crate clipper2

clipper2 is a path/polygon clipping and offsetting library that supports operations like difference, inflate, intersect, point-in-polygon, union, xor, simplify.

The create uses the clipper2c-sys crate that in turn is a Rust wrapper around the C++ version of Clipper2.

The crate exposes the Clipper API in two alternative ways until the best version has been figured out.

1. Through the Path/Paths struct methods:
   • Path::inflate
   • Path::simplify
   • Path::is_point_inside
   • Paths::inflate
   • Paths::simplify
   • Paths::to_clipper_subject returns a Clipper builder struct with the current set of paths as the first subject, and allowing to make boolean operations on several sets of paths in one go.
   • Paths::to_clipper_open_subject similar but adds the current set of paths as an open “line” rather than a closed path/polygon.
2. Via the plain functions:
   • difference
   • inflate
   • intersect
   • point_in_polygon
   • simplify
   • union
   • xor

The Path/Paths structs also thas some transformation methods such as:

• Path::translate / Paths::translate for moving a path in by a x/y offset
• Path::rotate / Paths::rotate for rotating a path in by x radians
• Path::scale / Paths::scale for scaling a path by multiplier

Examples

use clipper2::*;

let path_a: Paths = vec![(0.2, 0.2), (6.0, 0.2), (6.0, 6.0), (0.2, 6.0)].into();
let path_b: Paths = vec![(5.0, 5.0), (8.0, 5.0), (8.0, 8.0), (5.0, 8.0)].into();

let output: Vec<Vec<(f64, f64)>> = path_a
    .to_clipper_subject()
    .add_clip(path_b)
    .difference(FillRule::default())?.
    into();

dbg!(output);

More examples can be found in the examples directory.

Structs

• Bounds
  Represents an area from one min and one max Point.
• Centi
  Scale by 100. This is the default.
• Clipper
  The Clipper struct used as a builder for applying boolean operations to paths.
• Deci
  Scale by 10.
• Milli
  Scale by 1000.
• NoSubjects
  A state indicating no subjects and no clips.
• One
  No scaling.
• Path
  A collection of points.
• PathIterator
  An iterator over the points in a path.
• Paths
  A collection of paths.
• PathsIterator
  An iterator over the paths.
• Point
  XY Point with custom scaler.
• WithClips
  A state indicating one or more subjects and one or more clips.
• WithSubjects
  A state indicating one or more subjects and no clips.

Enums

• ClipperError
  Errors that can occur during clipper operations.
• EndType
  The EndType enumerator is only needed when offsetting (inflating/shrinking). It isn’t needed for polygon clipping.
• FillRule
  The Clipper Library supports 4 filling rules: Even-Odd, Non-Zero, Positive and Negative. These rules are base on the winding numbers (see below) of each polygon sub-region, which in turn are based on the orientation of each path. Orientation is determined by the order in which vertices are declared during path construction, and whether these vertices progress roughly clockwise or counter-clockwise.
• JoinType
  The JoinType enumeration is only needed when offsetting (inflating/shrinking). It isn’t needed for polygon clipping. It specifies how to manage offsetting at convex angled joins. Concave joins will always be offset with a mitered join.
• PointInPolygonResult
  The result indicates whether the point is inside, or outside, or on one of the specified polygon’s edges.

Traits

• ClipperState
  The state of the Clipper struct.
• PointScaler
  The point scaling trait allows to choose a multiplier for the point values at compile time.

Functions

• difference
  This function differences closed subject paths from clip paths.
• inflate
  These functions encapsulate ClipperOffset, the class that performs both polygon and open path offsetting.
• intersect
  This function intersects closed subject paths with clip paths.
• point_in_polygon
  The function result indicates whether the point is inside, or outside, or on one of the specified polygon’s edges.
• simplify
  This function removes points that are less than the specified epsilon distance from an imaginary line that passes through its 2 adjacent points. Logically, smaller epsilon values will be less aggressive in removing points than larger epsilon values.
• union
  This function ‘unions’ closed subject paths, with and without clip paths.
• xor
  This function ‘XORs’ closed subject paths and clip paths.