Go through UFOs in directory and orient contour paths in a counter-clockwise direction. See https://github.com/googlefonts/fontmake/issues/846

1--orient-glyph-contours-UFOs_in_dir.py

"""

    ⚠️⚠️⚠️
    OOPS. Don’t use this. FontParts already has BaseGlyph.correctDirection()
    ⚠️⚠️⚠️

    Go through UFOs in directory and orient contour paths in a counter-clockwise direction,
    as they should be for cubic/postscript/CFF/"OTF" curves.

    DEPENDENCIES:
    - fontParts
    - ufonormalizer

    USAGE:
    On the command line, call this script and add a directory of UFOs as an argument. 
    Add "--normalize" to normalize the UFOs after saving.

        python3 <path_to_script>/orient-glyph-contours-UFOs_in_dir.py <path_to_directory_of_UFOs> --normalize

    DISCLAIMERS: 
    - May break compatibility on some glyphs, as start points can change. Consider using Prepolator, afterwards.
    - May result in some broken drawings for certain edge cases (e.g. if a counter path 
      somehow goes further left than the main exterior path).
    - Doesn't handle glyphs with more than two counters, unless they all have the same 
      path direction (i.e. no counters), but adds these to a list for manual review.
    - May not work for your project. ¯\_(ツ)_/¯ ALWAYS USE GIT / VERSION CONTROL or another 
      form of backup before running any script like this!

    LICENSE:
    - MIT. Use/remix this if you want to.

"""

import argparse
import os
from fontParts.world import *
from ufonormalizer import normalizeUFO


def orientPathsCCW(glyph):
    """
        Orient all paths in glyph counter-clockwise.
        Only use this on glyphs with no counter/cutout shapes.
    """
    for contour in glyph:
        if contour.clockwise == True:
            contour.reverse()


def main():

    # get arguments from argparse
    args = parser.parse_args()

    sourceFolderPath = args.dir

    # get UFO paths and open each of them
    for subPath in os.listdir(sourceFolderPath):
        if subPath.endswith(".ufo"):
            ufoPath = os.path.join(sourceFolderPath, subPath)

            f = OpenFont(ufoPath, showInterface=False)

            print(f"Analyzing: {f.info.styleName}...")

            # a list to track glyphs with many contours, for manual review
            manyContours = []

            # go through glyphs in the font
            for g in f:

                # if all contours have the same path direction, orient the paths CCW
                if len(set([c.clockwise for c in g.contours])) == 1:
                   orientPathsCCW(g)

                # else if contours have more than one direction
                else:
                    # check for exactly two contours
                    if len(g.contours) == 2:

                        # find outer shape, then make it CCW
                        # if first contour is further left than second contour, assume it is exterior and orient first to CCW
                        # bounds is (xMin, yMin, xMax, yMax)
                        if g.contours[0].bounds[0] < g.contours[1].bounds[0]:
                            if g.contours[0].clockwise:
                                g.contours[0].reverse()
                                g.contours[1].reverse()

                        # if first contour is not further left, assume it is the counter, and make it CW
                        else:
                            if g.contours[0].clockwise == False:
                                g.contours[0].reverse()
                                g.contours[1].reverse()

                    # if too many contours, just add to a list for manual review/handling
                    if len(g.contours) == 3:
                        manyContours.append(g.name)

            # report list for manual review
            if len(manyContours) >= 1:
                print("The following glyphs have more than two contours, and multiple path directions:")
                print(" ".join(manyContours))
                print()

            f.save()

            if args.normalize:
                normalizeUFO(ufoPath)

if __name__ == "__main__":

    parser = argparse.ArgumentParser(description='Orient path directions in all glyphs for all UFOs in a directory.')

    parser.add_argument('dir',
                        help='Relative path to a directory of one or more UFO font sources')
    parser.add_argument("-n", "--normalize",
                        action='store_true',
                        help='Normalizes UFOs with ufoNormalizer.')
    main()

2--orient-specific-glyphs-UFOs_in_dir.py

"""

    ⚠️⚠️⚠️
    OOPS. Don’t use this. FontParts already has BaseGlyph.correctDirection()
    ⚠️⚠️⚠️

    Go through UFOs in directory and make all contours clockwise in specified glyphs.

    Steps to usage:
    1. First, use orient-glyph-contours-UFOs_in_dir.py to fix simpler glyphs and report complex glyphs.
    2. Open one of the UFOs and manually check which of the complex glyphs have incorrect paths.
    3. Add glyphs with backwards paths and counters to the "reverse" space-separated string, below.
    4. Add glyphs with differing paths and no counters to the "coordinate" space-separated string, below.
    5. Run the script on a directory of UFOs. Add "--normalize" arg to normalize UFOs.
    
    DEPENDENCIES:
    - fontParts
    - ufonormalizer

    DISCLAIMERS: 
    - May break compatibility on some glyphs, as start points might change. Consider using Prepolator, afterwards.
    - May result in some broken drawings for certain edge cases (e.g. if a counter path 
      somehow goes further left than the main exterior path).
    - May not work for your project. ¯\_(ツ)_/¯ ALWAYS USE GIT / VERSION CONTROL or another 
      form of backup before running any script like this!

    LICENSE:
    - MIT. Use/remix this if you want to.
"""

import argparse
import os
import collections
from fontParts.world import *
from ufonormalizer import normalizeUFO

# -----------------------------------------
# CONFIGURE GLYPHS BELOW
# Yes, these could instead be command line args, but this is easier. Feel free to modify if you want!

glyphsToReverse = "eth copyright"
glyphsToCoordinate = "divide"

# CONFIGURE GLYPHS ABOVE
# -----------------------------------------


def orientPathsCCW(glyph):
    """
        Orient all paths in glyph counter-clockwise.

        Only use this on glyphs with no counter/cutout shapes!
    """
    for contour in glyph:
        if contour.clockwise == True:
            contour.reverse()


def main():

    # get arguments from argparse
    args = parser.parse_args()

    sourceFolderPath = args.dir

    for subPath in os.listdir(sourceFolderPath):
        if subPath.endswith(".ufo"):
            ufoPath = os.path.join(sourceFolderPath, subPath)
            
            f = OpenFont(ufoPath, showInterface=False)

            print(f"Fixing: {f.info.styleName}...")

            try:
                # go through list of glyphs to reverse
                for name in glyphsToReverse.split(" "):
                    # make orderedDict of contours, by leftmost bound
                    contoursLeftBounds = {}
                    for i, c in enumerate(f[name].contours):
                        # add contours to dict, by bounds[0]: contourIndex
                        contoursLeftBounds[c.bounds[0]] = i
                    contoursLeftBoundsSorted = collections.OrderedDict(sorted(contoursLeftBounds.items()))

                    # get index of leftmost contour
                    leftmostContourIndex = list(contoursLeftBoundsSorted.items())[0][1]

                    # if the leftmost contour is clockwise, assume all paths are wrong and reverse them
                    if f[name].contours[leftmostContourIndex].clockwise == True:
                        for c in f[name].contours:
                            c.reverse()

                # go through list to coordinate
                for name in glyphsToCoordinate.split(" "):
                    orientPathsCCW(f[name])
            
            except KeyError:
                pass


            f.save()
            
            if args.normalize:
                normalizeUFO(ufoPath)

if __name__ == "__main__":

    parser = argparse.ArgumentParser(description='Orient path directions in all glyphs for all UFOs in a directory.')

    parser.add_argument('dir',
                        help='Relative path to a directory of one or more UFO font sources')
    parser.add_argument("-n", "--normalize",
                        action='store_true',
                        help='Normalizes UFOs with ufoNormalizer.')
    main()