Why doesn't Subtract work in Designer?

[Stokestack]

I have a pretty simple example here. Trying to cut a hole in a shape using a smaller one. It doesn't work. The smaller object is deleted but has no effect on the larger, regardless of stacking order.

Project file attached. This is supposed to work, as demonstrated in Affinity's own video here: 

 

This doesn't work for me (Designer 1.8.4 on Mac OS 10.15.7)

subtracTest.afdesign

[Old Bruce]

I changed the Fill mode on both to Alternate (Even/Odd) from Winding (Non-Zero). This is in the Layer > Fill Mode >... and it worked fine.

[Stokestack]

Thanks for the reply, and taking the time to do that.

But the fillable area is depicted as solid for both shapes; they don't have lines crossing themselves. Not to mention:

• This isn't mentioned in the documentation on boolean operations.
• This isn't shown in the Affinity video.
• That's a mighty obscure setting and description.
• Why would it default to a fill type that renders these operations unusable?

I loaded the same file into Sketch and had the shape punched out in less than 10 seconds: Select the two layers and press Subtract. Done. So there doesn't appear to be anything ambiguous about the shapes that should require fiddling with an obscure fill-interpretation setting.

But since you know a thing or two, any idea about this one: 

 

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[Stokestack]

Thanks a lot for the info.

That's disappointing. I don't know what the priorities are for the dev team, when so many fundamental functions don't work. You can't reliably combine shapes or do boolean operations, in addition to baffling UI-design mistakes... I'm pretty fed up with it.

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[lepr]

On 11/10/2020 at 9:08 AM, Lagarto said:

way it works in Affinity apps, is unexpected at least from the point of view of needing to apply it in context of Boolean subtract operation.

In Affinity apps, the result of the Boolean operation inherits the fill mode of the lowest operand.

The most common reason for an object to have winding fill in an Affinity app seems to be that the object has been imported from a file created by another app, although converting Text to Curves sometimes results in winding fill.

[Alfred]

4 hours ago, anon2 said:

converting Text to Curves sometimes results in winding fill

The ‘sometimes’ is presumably because the contours in a glyph are usually clockwise, but a contour is counterclockwise if it needs to be subtracted from another one (e.g. to form the counter, or ‘hole’, in the letter O).

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[lepr]

3 hours ago, Lagarto said:

However when the same is done with Inkscape, subtraction happens as expexted (with "hole"), but at the same time the fill mode stays as "Winding"), and changing the fill mode does not have any effect.

When the outer and inner paths of the result have opposing directions, both winding and alternate fill modes should produce the appearance of a hole cut out of the shape.

When the outer and inner paths of the result have the same direction, winding fill mode should produce the appearance of no hole, but alternate fill mode should produce the appearance of a hole.

[lepr]

4 hours ago, Alfred said:

The ‘sometimes’ is presumably because the contours in a glyph are usually clockwise, but a contour is counterclockwise if it needs to be subtracted from another one (e.g. to form the counter, or ‘hole’, in the letter O).

Maybe I should have said always instead of sometimes. I seem to remember a particular font was unusually being converted to Curve/Curves with alternate fill, but I may be mistaken.

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[Stokestack]

Well, thanks for all that elucidation, people! This shape was loaded as an SVG, so the importation guess was right.

I still think the dysfunction exhibited here is ridiculous, since I was able to load the same image in Sketch and it somehow managed to do the expected thing instantly.

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[Stokestack]

Thanks. I have wondered how apps make the fill decisions when shapes have outlines that that cross themselves... but I think we agree that we shouldn't have to wonder about it when they don't.

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[Stokestack]

Thanks for that.

I'm a big fan of Corel Draw, and hater of Illustrator. Before Designer, I'd run Windows in a VM just to run Draw.

Sadly, the more I use Designer, the more disappointed I am in it. It's crippled by defects in so many essential functions, and the UI.

 

[Stokestack]

8 hours ago, BofG said:

@Stokestack I'm curious to know, did your svg file specify a fill-rule?

Not that I know of...

[Stokestack]

Here's an SVG.

Works fine in Sketch, not Designer.

subtracTest.svg

[lepr]

18 minutes ago, Stokestack said:

Here's an SVG.

Works fine in Sketch, not Designer.

subtracTest.svg 1.32 kB · 1 download

The lower shape has fill-rule nonzero (Winding) specified in the SVG, so it gets Winding mode in Affinity and so the result of the subtraction is given Winding mode which makes no hole appear.

[Stokestack]

Thanks.  Hopefully Affinity can get this fixed. Pretty sure nobody's holding his breath at this point, though.

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[Stokestack]

Not surprised. I'm downloading the trial Mac version of Corel Draw right now. Their attempts at a Mac version have historically been rendered unusable by bugs, but we'll see about this 2020 one...