extracting vertices_list and faces_list with ezdxf

Question

I am trying to correctly extract vertices and faces from POLYLINE(POLYFACE) DXF files. When I try to create a Trimesh after extraction nothing is showing up. Any idea?

doc = ezdxf.readfile(r"C:\Users\Baldan\Downloads\simplified.dxf")
msp = doc.modelspace()

vertices = []
faces = []
for e in msp:
    
for vertex in e.vertices:
    if vertex.is_face_record:
        # Extract face information
        indices = [vertex.get_dxf_attrib(name, 0) for name in ('vtx0', 'vtx1', 'vtx2', 'vtx3')]
        # Filter out 0 indices as they indicate the end of the face definition
        indices = [idx for idx in indices if idx != 0]
        faces.append(tuple(indices))
    # Assuming vertex is a DXFVertex with a .dxf.location attribute
    x, y, z = vertex.dxf.location
    vertices.append((x, y, z))

mesh = trimesh.Trimesh(vertices=vertices, faces=faces)
mesh.export('test.ply', file_type='ply')

Answer 1

You have to separate the face and location VERTEX entities and for some unknown reason are the vertex indices 1-based:

doc = ezdxf.readfile(r"C:\Users\Baldan\Downloads\simplified.dxf")
msp = doc.modelspace()

def trimesh_from_polyface(polyface):
    vertices = []
    faces = []
    for vertex in polyface.vertices:
        if vertex.is_face_record:
            # Extract face information
            indices = [vertex.get_dxf_attrib(name, 0) for name in ('vtx0', 'vtx1', 'vtx2', 'vtx3')]
            # Filter out 0 indices as they indicate the end of the face definition
            # Vertex indices are 1-based!
            indices = [idx-1 for idx in indices if idx != 0]
            faces.append(tuple(indices))
        elif vertex.is_poly_face_mesh_vertex:    
            x, y, z = vertex.dxf.location
            vertices.append((x, y, z))
    return trimesh.Trimesh(vertices=vertices, faces=faces)

    
for e in msp.query("POLYLINE"):
    if e.is_poly_face_mesh:
        mesh = trimesh_from_polyface()
        mesh.export('test.ply', file_type='ply')