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RoboFont does recurve as much as possible when deleting a point.

So that means all the building blocks are there to make a clean up tool.

the plan:

• make a copy of the glyph
• delete one point in the copy
• check if curve is almost the same as the original, maybe with an controlled error value
• continue doing this until you can not delete points anymore or when all points are required to draw the shape

good luck!!!

Just wrote it down in pseudo code how to solve this. I dont have much time left. Not my intention to scare you, more to trigger you or someone else to write this little script :)

1. Copy the contour and then paste it to a background layer. Make sure this layer is visible, via the Inspector.
2. Select a point that isn’t needed, and hit delete. Adjust the path as needed to match the background contour as much as you want, while considering whether you can improve upon that.
3. Repeat!

If you had a bunch of glyphs to clean up, this would obviously be a hassle. But, often, it is probably better to have precise control over exactly how you are simplifying paths. It will result in cleaner curves, and helps you be careful to consider interpolation compatibility as you go (if needed).

It works in my case because the the non-extrema points are usually extraneous, so the RoboFont point-deletion recurve algorithm "solves" the deletion correctly.

No error checking or anything like that, as Frederik suggested, but hopefully it might still help you.

for glyph in CurrentFont():
    glyph.deselect()
    for contour in glyph.contours:
        for bp in contour.bPoints:
            ix, iy = bp.bcpIn
            ox, oy = bp.bcpOut
            if bp.type == "corner":
                continue
            if abs(ox-ix) > 5 and abs(oy-iy) > 5:
                bp.selected = True

    if True:
        glyph.removeSelection(
            removePoints=True,
            removeComponents=False,
            removeAnchors=False,
            removeImages=False)

import math

def calc_vector(point1, point2):
    x1, y1 = point1
    x2, y2 = point2
    dx = x2 - x1
    dy = y2 - y1
    return dx, dy

def calc_angle(point1, point2):
    dx, dy = calc_vector(point1, point2)
    return math.degrees(math.atan2(dy, dx))

def bp_angles(bp):
    ax, ay = bp.anchor
    ix, iy = bp.bcpIn
    ox, oy = bp.bcpOut
    in_angle = calc_angle((ix+ax, iy+ay), bp.anchor)
    out_angle = calc_angle(bp.anchor, (ox+ax, oy+ay))
    diff = abs(in_angle - out_angle)
    return in_angle, out_angle, diff

def select_extra_points(glyph, remove=False):
    if False: # flip to True if you want to select a point and see it’s angles printed, useful for debugging
        for bp in glyph.selectedBPoints:
            in_angle, out_angle, diff = bp_angles(bp)
            print("----------", in_angle, out_angle, diff)
    else:
        glyph.deselect()
        for contour in glyph.contours:
            for bp in contour.bPoints:
                in_angle, out_angle, diff = bp_angles(bp)
                if diff < 10:
                    if abs(abs(in_angle / 90) - round(abs(in_angle / 90))) > 0.1:
                        bp.selected = True

        if remove:
            glyph.removeSelection(
                removePoints=True,
                removeComponents=False,
                removeAnchors=False,
                removeImages=False)
                
glyph = CurrentGlyph()
#glyph.removeOverlap(round=1)
select_extra_points(glyph, remove=False)

# To run on the entire font
#for glyph in CurrentFont():
#    select_extra_points(glyph, remove=True)