How to construct a `Mesh` from faces containing `TriangleFace` and `QuadFace` with GeometryBasics

[kimikage]

I am trying to do read/write of a simple Wavefront .obj file without triangulation.

However, the following will result in an error.

julia> using GeometryBasics # v0.4.10

julia> vertices = Point3f[(0, 0, 0), (1, 0, 0), (1, 1, 0), (0, 1, 0), (0, 0, 1)];

julia> faces = [QuadFace(1, 2, 3, 4), TriangleFace(5, 2, 1)];

julia> Mesh(vertices, faces)
ERROR: MethodError: no method matching Polytope(::Type{Point{3, Float32}}, ::Type{NgonFace{S, Int64} where S})

julia> VERSION
v"1.10.2"

The construction will succeed if the type is sufficiently qualified as follows:

using GeometryBasics
import GeometryBasics.Ngon

TQFace = Union{TriangleFace{Int},QuadFace{Int}}
TQNgon = Union{Triangle{3,Float32}, Ngon{3,Float32,4,Point3f}}

vertices = Point3f[(0, 0, 0), (1, 0, 0), (1, 1, 0), (0, 1, 0), (0, 0, 1)]
tqfaces = TQFace[QuadFace(1, 2, 3, 4), TriangleFace(5, 2, 1)]

faceview = FaceView{TQNgon,Point3f,TQFace,Vector{Point3f},Vector{TQFace}}(vertices, tqfaces); # `show` throws an error

mesh = Mesh(faceview); # `show` throws an error

julia> faces(mesh) # seems to be working
2-element Vector{Union{TriangleFace{Int64}, QuadFace{Int64}}}:
 [1, 2, 3, 4]
 TriangleFace(5, 2, 1)

Are there additional packages that would be useful for this use case?

[mkitti]

What you probably want to do is convert all of your faces to TriangleFace

[kimikage]

Triangulation is an irreversible process.
On the other hand, converting a TriangleFace to a QuadFace with duplicate vertices may work.
However, I do not know if the workaround is common.

[juliohm]

Meshes.jl is what you need, most likely.

[kimikage]

IIUC, Meshes.jl is independent of the GeometryBasics.jl ecosystem.
I prefer Meshes.jl’s design, but there is some resistance to say goodbye to GeometryBasics.jl.

Regardless, my objective can be achieved, and I would like to use Meshes.jl as a solution.

[kimikage]

Using Meshes.jl, a mesh with triangular and rectangular faces could be generated from the SVG of Julia’s logo.