Edit again:
Well I might as well reply to this. I tend to avoid PyMEL because it’s just another wrapper on the underlying Maya language interfaces. While it can be extremely convenient for what you might need to do, it might hide functionality that might be otherwise available to you.
Case in point, you should spend some time learning the Python API as it can give you lower level access to things like this and be scriptable to boot.
I’ve written up a quick example that tests if a given uv_id is on an edge_id:
import maya.api.OpenMaya as om
import maya.cmds as cmds
def get_local_vertex_id( face_vertices, vert_id ):
"""
Helper function that returns the local face-relative index
given a mesh-relative index. If it cannot locate vert_id
in the face_vertices list, it returns -1.
Many of the iterator interfaces look for a local face-relative
index rather than the mesh-relative vertex index. That is to say
if your face has vertices [10, 12, 11, 9]. Then:
vertex 10 is at local index 0
vertex 12 is at local index 1
etc.
"""
for i in range(len(face_vertices)):
if vert_id == face_vertices[i]:
return i
return -1
def is_uv_on_edge( mesh, edge_id, uv_id ):
"""
Given the name of a mesh transform or shape, this function
will return True if the given edge_id is connected to the
given uv_id on the default map set.
"""
# Retrieve the mesh DAG path
sel_list = om.MSelectionList()
sel_list.add( mesh_shape )
path = sel_list.getDagPath( 0 )
path.extendToShape()
# Retrieve the edge vertices.
# It's easier to do it by vertices than edges because
# of the interface.
mesh_fn = om.MFnMesh( path.node() )
verts = mesh_fn.getEdgeVertices( edge_id )
# Iterate over the faces of the polygon.
iter = om.MItMeshPolygon( path.node() )
while not iter.isDone():
# For each face, look at the vertices that make up the face
# and test to see if the edge vertices appear in the face.
# If so, look up the UV id for that local vertex and compare
# if it matches our uv_id
face_vertices = iter.getVertices()
for v in verts:
local_id = get_local_vertex_id( face_vertices, v )
if local_id < 0:
continue
mesh_uv = iter.getUVIndex( local_id )
if mesh_uv == uv_id:
return True
# Passing in iter into the next must be a Python API 2.0 bug
iter.next(iter)
return False
if __name__ == '__main__':
# Quick polyCube testing.
# edge_id = 0 should be linked to uv_id=(0,1)
cmds.file(f=True, new=True)
mesh = cmds.polyCube()[0]
edge_id = 0
uv_id = 1
print is_uv_on_edge( mesh, edge_id, uv_id )
