Simple UV Script: Error # Error: RuntimeError: file <maya console> line 82: (kInvalidParameter): No element at given index


I have been trying to use a script meant to export xgen interactive groom UVs as an alembic file so it can be imported in Unreal engine and textured with the correct UVs. For some reason I keep running into the error “# Error: RuntimeError: file line 82: (kInvalidParameter): No element at given index”.

I have no idea what’s wrong because the script seems tot work with other meshes and xgen scenes. I have pasted the script below.

`from maya import cmds
from maya import OpenMaya
import os

def create_root_uv_attribute(curves_group, mesh_node, uv_set=‘map1’):
Create “groom_root_uv” attribute on group of curves.

# check curves group
if not cmds.objExists(curves_group):
    raise RuntimeError('Group not found: "{}"'.format(curves_group))

# get curves in group
curve_shapes = cmds.listRelatives(curves_group, shapes=True, noIntermediate=True)
curve_shapes =, type='nurbsCurve')
if not curve_shapes:
    raise RuntimeError('Invalid curves group. No nurbs-curves found in group.')
    print ("found curves")
    print (curve_shapes)

# get curve roots
points = list()
for curve_shape in curve_shapes:
    point = cmds.pointPosition('{}.cv[0]'.format(curve_shape), world=True)

# get uvs
values = list()
uvs = find_closest_uv_point(points, mesh_node, uv_set=uv_set)
for u, v in uvs:
    values.append([u, v, 0])
    #print (str(u) + " , " + str(v)  )

# create attribute
name = 'groom_root_uv'
cmds.addAttr(curves_group, ln=name, dt='vectorArray')
cmds.addAttr(curves_group, ln='{}_AbcGeomScope'.format(name), dt='string')
cmds.addAttr(curves_group, ln='{}_AbcType'.format(name), dt='string')

cmds.setAttr('{}.{}'.format(curves_group, name), len(values), *values, type='vectorArray')
cmds.setAttr('{}.{}_AbcGeomScope'.format(curves_group, name), 'uni', type='string')
cmds.setAttr('{}.{}_AbcType'.format(curves_group, name), 'vector2', type='string')

return uvs

def find_closest_uv_point(points, mesh_node, uv_set=‘map1’):
Find mesh UV-coordinates at given points.

# check mesh
if not cmds.objExists(mesh_node):
    raise RuntimeError('Node not found: "{}"'.format(mesh_node))

# check uv_set
uv_sets = cmds.polyUVSet(mesh_node, q=True, allUVSets=True)
if uv_set not in uv_sets:
    raise RuntimeError('Invalid uv_set provided: "{}"'.format(uv_set))

# get mesh as dag-path
selection_list = OpenMaya.MSelectionList()

mesh_dagpath = OpenMaya.MDagPath()
selection_list.getDagPath(0, mesh_dagpath)

# get mesh function set
fn_mesh = OpenMaya.MFnMesh(mesh_dagpath)

uvs = list()
for i in range(len(points)):

    script_util = OpenMaya.MScriptUtil()
    script_util.createFromDouble(0.0, 0.0)
    uv_point = script_util.asFloat2Ptr()

    point = OpenMaya.MPoint(*points[i])
    fn_mesh.getUVAtPoint(point, uv_point, OpenMaya.MSpace.kWorld, uv_set)

    u = OpenMaya.MScriptUtil.getFloat2ArrayItem(uv_point, 0, 0)
    v = OpenMaya.MScriptUtil.getFloat2ArrayItem(uv_point, 0, 1)

    uvs.append((u, v))

return uvs

def abc_export(filepath, node=None, start_frame=1, end_frame=1, data_format=‘otawa’, uv_write=True):

job_command = '-frameRange {} {} '.format(start_frame, end_frame)
job_command += '-dataFormat {} '.format(data_format)

job_command += '-attr groom_root_uv '

if uv_write:
    job_command += '-uvWrite '

job_command += '-root {} '.format(node)   

job_command += '-file {} '.format(filepath) 

cmds.AbcExport(verbose=True, j=job_command)

def main():

export_directory = ('C:\\Users\\NAME\\OneDrive\\Documents\\Zbrush\\MayaTransfer')
hair_file = os.path.join(export_directory, '')
curve_top_group= 'SplineGrp0'

create_root_uv_attribute( curve_top_group , uv_mesh)
abc_export(hair_file, curve_top_group)