iOverlay

Balloons

The iOverlay is a fast poly-bool library supporting main operations like union, intersection, difference, and xor, governed by either the even-odd or non-zero rule. This algorithm is based on Vatti clipping ideas but is an original implementation.

Documentation

Try out iOverlay with an interactive demo:

Features

Operations: union, intersection, difference, and exclusion.
Polygons: with holes, self-intersections, and multiple paths.
Simplification: removes degenerate vertices and merges collinear edges.
Fill Rules: even-odd and non-zero.

Getting Started

Add the following to your Cargo.toml:

[dependencies]
i_overlay = "^1.4"

Hello world

Let's union two squares

let subj = [
    F64Point::new(-10.0, -10.0),
    F64Point::new(-10.0, 10.0),
    F64Point::new(10.0, 10.0),
    F64Point::new(10.0, -10.0),
];

let clip = [
    F64Point::new(-5.0, -5.0),
    F64Point::new(-5.0, 15.0),
    F64Point::new(15.0, 15.0),
    F64Point::new(15.0, -5.0),
];

let mut overlay = FloatOverlay::new();

overlay.add_path(&subj, ShapeType::Subject);
overlay.add_path(&clip, ShapeType::Clip);

let graph = overlay.into_graph(FillRule::NonZero);
let shapes = graph.extract_shapes(OverlayRule::Union);

println!("shapes count: {}", shapes.len());

if shapes.len() > 0 {
    let contour = &shapes[0][0];
    println!("shape 0 contour: ");
    for p in contour {
        let x = p.x;
        let y = p.y;
        println!("({}, {})", x, y);
    }
}

Shapes result

The output of the extract_shapes function is a Vec<Vec<Vec<F64Point>>>, where:

The outer Vec<F64Shape> represents a set of shapes.
Each shape Vec<F64Path> represents a collection of paths, where the first path is the outer boundary, and all subsequent paths are holes in this boundary.
Each path Vec<F64Point> is a sequence of points, forming a closed path.

Note: Outer boundary paths have a clockwise order, and holes have a counterclockwise order.