orderMeshStripFaces.py

import Rhino as rc

def meshEndFaces(mesh):
    
    """ Get indices of faces with only one neighbour """ 
    
    endFaces = []
    for i in range(mesh.Faces.Count):
        af = mesh.Faces.AdjacentFaces(i)
        if len(af) == 1:
            endFaces.append(i)
            
    return endFaces

def lowestEndFace(mesh):
    
    """ Get index of lowest end face """
    
    efA,efB = meshEndFaces(mesh)
    efAZ = mesh.Faces.GetFaceCenter(efA).Z
    efBZ = mesh.Faces.GetFaceCenter(efB).Z
    if efAZ < efBZ:
        ef = efA
    else:
        ef = efB
        
    return ef

def orderMeshStripFaces(mesh):
    
    """ Reorder the faces to start from the lowest end face (by Z values )"""
    
    if mesh.Faces.Count > 1:
        
        # Make new mesh and vertices to it
        nMesh = rc.Geometry.Mesh()
        nMesh.Vertices.AddVertices(mesh.Vertices.ToPoint3dArray())
        
        # Add faces starting from lowest end face
        vf = [lowestEndFace(mesh)]
        for i in range(mesh.Faces.Count):
            
            # Add face
            nMesh.Faces.AddFace(mesh.Faces[vf[-1]])
            
            # Get index of next face
            fnb = mesh.Faces.AdjacentFaces(vf[-1])
            nf = list(set(fnb) - set(vf))
            if nf:
                vf.append(nf[0])
                
        # Set normals, color and return nMesh
        nMesh.Normals.ComputeNormals()
        nMesh.FaceNormals.ComputeFaceNormals()
        if mesh.VertexColors.Count:
            nMesh.VertexColors.CreateMonotoneMesh(mesh.VertexColors.Item[0])
            
        return nMesh
        
    else:
        return mesh