Photo on Mac: marching ants to Path or vector?

[VectorCat]

I might be thinking of the way to do this in other software:

imagine a photo of a person playing tennis, about to whack the ball. You select them, the raquet and maybe the incoming ball, and you want to differentiate it from the background by any possible method..glowing, outline, in particular seem like you'd want to start with the marching ants, and then do your transform to that selection, but I don't know what the steps in Affinity are. 

In PS:  select to get marching ants, then in the path pallet you choose something like selection to path, and then you can do things to the path, which is in the shape of your selected object. That is just one way, and that's what I'm trying to do in Affinity Photo, but I'm wide open also to other methods

 

Thank you for any clues!

[Old Bruce]

In Photo it works well the other way, make your path/curve and then get the marching ants selection from that. 

In Photo there is no type of vector from marching ants selection. About the only thing to do to save the marching ants selection. is to make a spare channel from the selection in the Channels panel.

[loukash]

22 minutes ago, Old Bruce said:

In Photo there is no type of vector from marching ants selection.

You can relatively easily redraw straight marching ants selection lines with the Pen tool by enabling "Snap to pixel selection bounds".
If your selection already is a rectangle, then it's a no-brainer.

 

[Alfred]

1 hour ago, VectorCat said:

imagine a photo of a person playing tennis, about to whack the ball. You select them, the raquet and maybe the incoming ball, and you want to differentiate it from the background by any possible method..glowing, outline, in particular seem like you'd want to start with the marching ants, and then do your transform to that selection, but I don't know what the steps in Affinity are.

You don’t need a vector path for this. Make a ‘marching ants’ selection, duplicate the selection to a new layer and then apply a layer effect (e.g. ‘Outer Glow’) to the new layer.

[VectorCat]

1 minute ago, Alfred said:

You don’t need a vector path for this. Make a ‘marching ants’ selection, duplicate the selection to a new layer and then apply a layer effect (e.g. ‘Outer Glow’) to the new layer.

Right you are..thank you!

[loukash]

4 hours ago, Alfred said:

You don’t need a vector path for this

Just in case someone finds this thread later on:

4 hours ago, Old Bruce said:

vector from marching ants selection

Playing with the idea a bit more, here is a way via online converter:

1. make your marching ants selection
2. Layer > New Fill Layer (temporary)
3. Fill: full black
4. either disable all other layers (or if you export via Export persona, disable them there)
5. make sure Document > Transparent Background is disabled (or set Matte to white on PNG export)
6. Export > PNG
7. online-converting.com/vectorize > select SVG
8. drag & drop the exported PNG into the browser window (doesn't seem to work well with transparent PNG, hence #5)
9. download the converted *.svg
10. open the SVG with Photo (or Designer or Publisher, it doesn't matter)
11. copy the curve (it's a child of a group of a layer)
12. paste the curve into your Photo document; it should retain its exact original position
13. you can now enable all layers and delete the temporary fill layer

Caveats:

• PNG with transparencies may convert to full black rectangle via this particular converter, but your mileage may vary
• drag and dropping the SVG directly into the Photo window – or File > Place – places the SVG as an embedded document which you'd need to edit separately anyway to copy the actual path, thus adding one or two more steps

Compared to Photoshop:

1. make your marching ants selection
2. open the Paths panel
3. click the Make Work Path button

Sigh.
Ten steps too many.
But hey, it will take you there if you need it.