How to create a rectangle with trimesh.path.Path3D?

[xleEmesent]

Hi, All:

I am trying to create a 3D rectangle using trimesh.path.Path3D. But I am how to use trimesh.path.Path3D here?
The purpose is to cut a mesh with a polygon.
For example, if I have list of vertices as following:

    center = [0,0,0]
    width = 1
    depth = 2
    vs = np.array([
                    [center[0]-width/2, center[1], center[2]+depth/4], #left from the back
                    [center[0],center[1],center[2]+depth/4], #right from the back
                    [center[0],center[1]+height/2, center[2]+depth/4], #front right
                    [center[0]-width/2, center[1]+height/2, center[2]+depth/4]
                    ], #front left
                    dtype=np.float32)

    es = [[0, 1], [1, 2], [2, 3],[3,0]]

How could I create a trimesh.path.Path3D with above vertices and edges?
trimesh.path.Path3D(entities=None, vertices=None)

What is the "entities" here?
Thanks in advance.

[mikedh]

Hey, if you're using booleans you might want to do it with a trimesh.creation.box. But you can also create the outline of a box pretty easily:

In [1]: import trimesh

In [2]: trimesh.path.creation.box_outline?
Signature: trimesh.path.creation.box_outline(extents=None, transform=None, **kwargs)
Docstring:
Return a cuboid.

Parameters
------------
extents : float, or (3,) float
  Edge lengths
transform: (4, 4) float
  Transformation matrix
**kwargs:
    passed to Trimesh to create box

Returns
------------
geometry : trimesh.Path3D
  Path outline of a cuboid geometry
File:      ~/trimesh/trimesh/path/creation.py
Type:      function

In [3]: p = trimesh.path.creation.box_outline(extents=[10,4,3])

In [4]: p
Out[4]: <trimesh.Path3D(vertices.shape=(8, 3), len(entities)=1)>

In [5]: p.show()
Out[5]: SceneViewer(width=1800, height=1350)

[xleEmesent]

@mikedh , Many thanks for you reply.

However, I am a bit lost about your answer. I am intending to create a polygon using trimesh.path.Path3D. For example, a rectangle. So later on, I can use it to cut a mesh.

However, I am not sure how can use trimesh.path.Path3D here given edges and vetices here.

@mikedh , can you further clarify it? Thanks. (The polygon is actually in a plane)

[xleEmesent]

Also; the following error appeared when I did this:

es = np.array([0,1,2,3,0])
trimesh.path.Path3D(entities=es, vertices=vs)

lib/python3.7/site-packages/trimesh/path/path.py", line 228, in <genexpr>
    e._bytes() for e in self.entities))
AttributeError: 'numpy.int64' object has no attribute '_bytes'

[xleEmesent]

I think the solution is as following:
The parameter entities for Path3D requires a list of trimesh.path.entities.Line object instead of a single one.

el = trimesh.path.entities.Line([0,1,2,3,0])
trimesh.path.Path3D(entities=[el], vertices=vs)