Cut shapes with lines

[Resilient]

I have a workflow which requires me to take an image, overlay a set of lines or shapes, then slice, pull apart and arrange that image.

For example, see the attached image.

I would like to use those lines to slice the yellow square, then drag apart and arrange the resulting fragments of the square. (though in reality I would be using a JPG as a fill instead of a yellow square)

I am trying to convert over from Illustrator. There I could select all the shapes at once and as long as the square was the lowest layer, I could use the divide operation in the pathfinder to get the desired result. In Affinity Designer I can get a single division to work, but no more than that and it seems to only work once. Then it is converted into a curve and no longer divides as expected.

A typical image would have on the order of 200-500 pieces it would be divided into so this needs to be something that I can do quickly and efficiently.

Hopefully I am just missing an obvious divide setting or cut tool somewhere.

[PixelPest]

The fastest way is to give the strokes a minimal width ->Expand Stroke->Boolean add - then select with the object beneath Boolean->Subtract - Geometry->Separate Curves.

That process implies that cutting with "lines" is not poosible - just shapes.

[G13RL]

For a JPG, you can select it, "Convert to Curves".
Draw very thin cutting lines (0.05 mm for example), select them, "Expand Stroke".
Select the lines and the photo, do a Boolean operation "Divide". In the layers, select all the line segments at once (they will be on top of the stack), delete them.

[PixelPest]

Why "Divide" and not Boolean Subtract as above?  Same applies to converted bitmaps.

[G13RL]

The lines have been extended and the image converted into curves. With "Substract", the image (converted to curves) is transformed. Is it possible that I am missing something?

[PixelPest]

I´d call it a bug what happened with placed images. If you´re dragging a bitmap onto AffinityDesigner´s app icon to let it open (you first need to convert it to "image resource")- convert to curve - add the expanded/added thin strokes to subtract it works on the whole bitmap. It´s getting weirder when the image is upscaled.

 

[Resilient]

Thanks, this looks like it will work.

But I am getting two different non-ideal results.

If I use the subtract method, any changes I made to the size of the image are reset when I do the subtraction. This is solved by simply having the image be exactly the right size on import. But it would be good to be able to adjust it.

The other is that with the divide method I have to clean up the old lines that are left there.

 

In any case, the first subtraction method is workable. It would be good if I could resolve the scaling issue but fine if I can't. Thanks!

 

Edited August 16, 2021 by Resilient