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)LibTessSwift is available as a Swift Package Manager:
.package(url: "https://github.com/LuizZak/LibTessSwift.git", .exact("0.8.0"))LuizZak
LibTessSwift is available under the MIT license. See the LICENSE file for more info.