Polygonical

A library for interacting with polygons on a 2d plane.

Examples

Rotate a polygon: ```rust use polygonical::polygon::Polygon; use polygonical::point::Point;

let poly = Polygon::new(vec![
    Point::new(0.0, 1.0),
    Point::new(1.0, 1.0),
    Point::new(1.0, 0.0),
]);

// get the area of the polygon
let area = poly.area();

// rotate the polygon around its own center by 90 degrees
let rotated = poly.rotate_around_center(90.0_f64.to_radians());

println!("area: {} rotated: {}", area, rotated);

```

Create an approximation of a circle:

```rust use polygonical::polygon::Polygon; use polygonical::point::Point;

let num_points = 16;
let radius = 2.0;
let center = Point::new(10.0, 20.0);

// Note: we use an integer number of degrees here because rust won't let you iterate over floats like this.
let points = (0..360).step_by(360/num_points)
    .map(|a| Point::new(radius, 0.0).rotate((a as f64).to_radians()).translate(center))
    .collect();

let circle = Polygon::new(points);

let approx_area = circle.area();
let area = std::f64::consts::PI * radius * radius;

println!("area: {} aprox_area: {} difference: {}", area, approx_area, area - approx_area);

```

Features

• Points
• Polygons
• Bounding boxes
• Translations of points
• Polygons contain points
• Polygon isselfintersecting
• Polygon area
• Translations of polygons
• Rotations of points
• Rotations of polygons
• Overlap detection
• Contains detection

Wanted Features

Things we want to implement but haven't yet.

• Scale of points
• Scale of polygons
• Polygon unions
• Polygon subtraction

Unwanted Features

Things this library won't do.

• 3d Geometry
• Output to things like svg (that is for another library)
• Coordinate system transforms, epsg codes, pixel space to world space etc.

Design goals

• Correct
• Safe
• Fast

In that order

Limitations / Warnings

Polygons must be specified with the points going clockwise around them. Due to the way the contains point algorithm handles angles rolling over 360/0 degrees any function that relies on that algorithm will not work as expected.