Meshlab accessible direct from Blender python

Coding Released Scripts and Themes
2

Oh heres a minimal example of the actual process of exporting and importing to/from MeshLab. This example will take the selected object mesh and send it to MeshLab, then bring it back as a new mesh linked to the scene.
NB (!!) MeshLab will only import triangular meshes so you have to convert the mesh first.
Also MeshLab requires the mesh data to be in Numpy arrays, and Blender from_pydata requires it as standard lists (but this conversion is manaaged within the export/import functions).

import bpy
import pymeshlab
import numpy      



def exportMeshToMeshLab(blenderMesh):
    # NB pymeshlab is fussy
    # verts and faces have to be provided in a numpy array with verts as type float64 and faces as int32
    # faces have to be triangulated - quads and ngons are not allowed
    
    verts = []  #numpyp.empty((0,3), float64)
    for v in blenderMesh.vertices:
            verts.append([v.co[0], v.co[1], v.co[2]])
    verts = numpy.asarray(verts, dtype=numpy.float64)
    if len(verts) == 0:
        print("No vertices were found, so function aborting")
        return
#    print(verts.shape)   # must report (numOfVerts, 3)
#    print(verts.dtype.name)   # must report float64


    faces = []
    tooManyVerts = False
    for poly in blenderMesh.polygons:
        curFace = []
        for loop_index in range(poly.loop_start, poly.loop_start + poly.loop_total):
            curFace.append(blenderMesh.loops[loop_index].vertex_index)
        if len(curFace) == 3:
            faces.append(curFace)
        else:
            tooManyVerts = True
            
            
    if tooManyVerts:
        print("WARNING: Meshlab will only accept faces with THREE vertices")
    if len(faces) == 0:
        print("No triangular faces were found, so function aborting")
        return
    faces = numpy.asarray(faces, dtype=numpy.int32)
#    print(faces.shape)   # must report (numOfVerts, 3)
#    print(faces.dtype.name)

    # create a new Mesh with the two arrays
    meshlabMesh = pymeshlab.Mesh(verts, faces)

    # create a new MeshSet (a meshset can have multiple meshes each in a differnt layer - but that's not covered with this function)
    meshlabMeshSet = pymeshlab.MeshSet()

    # add the mesh to the MeshSet with the current name
    meshlabMeshSet.add_mesh(meshlabMesh, blenderMesh.name)

    return meshlabMeshSet


def importMeshFromMeshLab(meshlabMesh):
    # NB from_pydata in Blender is fussy
    # verts and faces have to be provided in a standard Python list (NOT a numpy array)
    
    verts = meshlabMesh.current_mesh().vertex_matrix().tolist()
    faces = meshlabMesh.current_mesh().face_matrix().tolist()
    #name = meshlabMesh.current_mesh().mesh_name()   # TODO: return this
    
    return verts, faces  #, name


print("START")

# Export a Blender mesh to MeshLab
me = bpy.context.object.data
meshlabMeshSet = exportMeshToMeshLab(me)

# Import a MeshLab mesh to Blender
verts, faces = importMeshFromMeshLab(meshlabMeshSet)
mesh = bpy.data.meshes.new("meshFromMeshLab")  # add the new mesh
mesh.from_pydata(verts, [], faces)   # this could also be done as a bmesh too...
ob = bpy.data.objects.new("meshFromMeshLab", mesh)
bpy.context.collection.objects.link(ob)


print(verts)
print(faces)

print("DONE")
1 Like