Polyskel

This is a Swift port of the Python Polyskel project, to generate straight skeleton algorithm as described by Felkel and Obdržálek in their 1998 conference paper Straight skeleton implementation.

Example

To run the example project, clone the repo and open Example/Polyskel.xcodeproj directly in Xcode.

Features

The library can generate straight skeletons, but also roof models, including the gabled style according to R. G. Laycock and A. M. Day Automatically Generating Roof Models from Building Footprints

Installation

Swift Package Manager

In Xcode, go to File → Add Package Dependencies and enter the repository URL:

https://github.com/andygeers/Polyskel-Swift

Or add it to your Package.swift:

.package(url: "https://github.com/andygeers/Polyskel-Swift.git", from: "0.4.0")

Migration from 0.x (CocoaPods)

Version 1.0 drops CocoaPods in favour of Swift Package Manager and upgrades the Euclid dependency to 0.8.x. There are two breaking changes:

Polygon materials are now RoofColor instead of UIColor. The library is now cross-platform and can no longer depend on UIKit. generateRoofPolygons() returns polygons whose material is a RoofColor(r:g:b:) value. In a UIKit app, convert it when building your SceneKit geometry:

SCNGeometry(mesh) { material in
    let scnMaterial = SCNMaterial()
    if let c = material as? RoofColor {
        scnMaterial.diffuse.contents = UIColor(red: CGFloat(c.r), green: CGFloat(c.g), blue: CGFloat(c.b), alpha: 1)
    }
    return scnMaterial
}

Euclid API changes. If you were calling Euclid APIs directly alongside Polyskel, see the Euclid changelog for 0.4–0.8 breaking changes (notably LineSegment(start:end:) labels and Polygon(_:material:) initializer).

Author

andy@geero.net based upon the code by Yongha Hwang and Ármin Scipiades (Botffy).

License

Polyskel is available under the MIT license. See the LICENSE file for more info.