A Swift wrapper on top of Libtess2 for polygon triangulation.
Tests where derived from LibTessDotNet library, which is also a port of the library above.
Also, a fix for an issue of 0-area polygons from libtess2 that was fixed by LibTessDotNet is also merged in.
Supports self-intersecting polygons and polygons with holes.
This is a sample wrapper over TessC to process polygons and return resultin vertices/indices pairs.
func process(polygon: [MyVector]) throws -> (vertices: [MyVector], indices: [Int])? {
let polygon: [MyVector] = ... // This should be an array of vertices - must have at least an `x` and `y` coordinate pairs!
guard let tess = TessC() else {
print("Something went wrong while initializing TessC! :c")
return nil
}
// Size of polygon (number of points per face)
let polySize = 3
// Map from MyVector to CVector3 (LibTessSwift's vector representation)
let contour = polygon.map {
CVector3(x: TESSreal($0.x), y: TESSreal($0.y), z: 0.0)
}
// Add the contour to LibTess
tess.addContour(contour)
// Tesselate - if no errors are thrown, we're good!
try tess.tessellate(windingRule: .evenOdd, elementType: .polygons, polySize: polySize)
// Collect resulting vector
var result: [MyVector] = []
var indices: [Int] = []
// Extract vertices
for vertex in tess.vertices! {
result.append(MyVector(x: vertex.x, y: vertex.y))
}
// Extract each index for each polygon triangle found
for i in 0..<tess.elementCount
{
for j in 0..<polySize
{
let index = tess.elements![i * polySize + j]
if (index == -1) {
continue
}
indices.append(index)
}
}
return (result, indices)
}
// Use away!
guard let (verts, indices) = try process(myVerts) else {
return
}
MyRenderer.drawPolygon(verts: verts, indices: indices)(note: I plan on adding a propper sample app later)
To run the example project, clone the repo, and run pod install from the Example directory first.
LibTessSwift is available through CocoaPods. To install it, simply add the following line to your Podfile:
pod "LibTessSwift"LuizZak
LibTessSwift is available under the MIT license. See the LICENSE file for more info.