Heads up display showing percentage of the UV area that current selected meshes/faces covers.

hud_uv_coverage.py

"""

    Custom Heads up display, displaying the area current selection covers in UV space.
    found this `gist <https://gist.github.com/SEVEZ/d86bf0a4a497794a94df8f125846ca4f>`_ from SEVEZ really useful.

"""

__author__ = "Andreas Ranman"

import maya.cmds as cmds
import maya.api.OpenMaya as om # maya python api 2.0

def uv_coverage(*args):
  """ Calculate the polygon area in UV space for selected meshes and polygon components

  :returns: formatted string with percent of coverage
  :rtype: str

  """

  area = 0.0

  selection = om.MGlobal.getActiveSelectionList()

  # Iterate selection, but only filter on polygon components,
  iterSelection = om.MItSelectionList(selection)
  while not iterSelection.isDone():
    dag, obj = iterSelection.getComponent()
    if not obj.isNull():
      if obj.hasFn(om.MFn.kMeshPolygonComponent):
        iterPoly = om.MItMeshPolygon(dag, obj)
        while not iterPoly.isDone():
          area += iterPoly.getUVArea()
          iterPoly.next(None) # Known bug on Autodesks side, since 2016 at least.
    iterSelection.next() 

  # Iterate over all meshes in selection,
  iterMesh = om.MItSelectionList(selection, om.MFn.kMesh)
  while( not iterMesh.isDone() ):
      dag, obj = iterMesh.getComponent()
      iterPoly = om.MItMeshPolygon(dag)
      while(not iterPoly.isDone()):
          area += iterPoly.getUVArea()
          iterPoly.next(None) # Known bug on Autodesks side, since 2016 at least.
      iterMesh.next()

  return "{} %".format(area * 100.0) # return the area as a percentage formatted string.
    
def toggle_hud():
  """ Toggle the HUD. """
    
  hud_name = "UVCoverage"

  # Using a check if it exists to work as a toggle, first run will create a hud, second will remove it.
  if not cmds.headsUpDisplay(hud_name, exists=True, query=True):
    cmds.headsUpDisplay(
      hud_name, 
      section=1, 
      block=0, 
      blockSize='medium', 
      label='UV Coverage', 
      labelFontSize='large', 
      command=uv_coverage, 
      event='SelectionChanged', 
      nodeChanges='attributeChange'
    )

  else:
    cmds.headsUpDisplay( hud_name, rem=True ) # remove any previously created hud from this script