Rs.MeshMeshIntersection help file typo?

At the rs.MeshMeshIntersection help file, there stands, that this function returns “None” when not successful (I guess this means too: when two meshes do not intersect?), or on error.

But when I took a look at the file, looks like when two meshes do not intersect, this function returns an empty list, not None:

def MeshMeshIntersection(mesh1, mesh2, tolerance=None):
    """Calculates the intersections of a mesh object with another mesh object
      mesh1, mesh2 = identifiers of meshes
      tolerance[opt] = the intersection tolerance
      List of 3d point arrays that define the vertices of the intersection curves
    mesh1 = rhutil.coercemesh(mesh1, True)
    mesh2 = rhutil.coercemesh(mesh2, True)
    if tolerance is None: tolerance = Rhino.RhinoMath.ZeroTolerance
    polylines = Rhino.Geometry.Intersect.Intersection.MeshMeshAccurate(mesh1, mesh2, tolerance)
    if polylines: return list(polylines)
    return []  # this line

Or did I get it all wrong?

We should probably fix the function and leave the help file as is. I’ve added this to the bug list.


– Dale

MeshMeshIntersection will return None instead of an empty list in SR9 (we’re too late for SR8). In either case, if you just have your code test the result like

results = rs.MeshMeshIntersection(.....)
if results:
  print "got results"

then your script will work the same if no matter if the function returns an empty list or None