# iOverlay

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](https://ishape-rust.github.io/iShape-js/overlay/stars_demo.html)
Try out iOverlay with an interactive demo:
- [Stars Rotation](https://ishape-rust.github.io/iShape-js/overlay/stars_demo.html)
- [Shapes Editor](https://ishape-rust.github.io/iShape-js/overlay/shapes_editor.html)
## 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_float = "^1.0.0"
i_overlay = "^1.0.0"
```
### Hello world
Let's union two squares
```rust
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.build_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);
}
}
```
# Overlay Rules
## Union, A or B

## Intersection, A and B

## Difference, B - A

## Exclusion, A xor B
