Given have two shapes for example. a star (blue) and arrow (no fill). The arrow has a green stroke.
How can I make the portion of the star which is behind the arrow transparent, but retain the green stroke on the arrow?
Hold down the Command/Ctrl key and click the layer thumbnail for the arrow in the Layers Panel. This will load the arrow shape as a selection.
Select > Inverse from the menu to invert the selection
Highlight the Star layer in the Layers Panel
New Mask icon at the bottom of the Layers Panel
This creates a mask which hides the portion of the star underneath the arrow shape.
It is difficult to know if the mask will be entirely correct because there are a couple of ways those shapes may have been created. The above assumes they are shape or vector layers. If the arrow is not a shape/vector layer, you may need to then grab a brush and paint black on the mask you just created in the center of the arrow to hide that portion of the star.
It's very Easy so, to make shape subtraction using Photoshop:
draw two shapes (lets take the above example).
make the arrow shape layer above the star shape layer.
make a copy from the arrow layer and make it invisible.
select both layers -visible arrow and the star- with (shift key).
go to the top menu: Layer > Combine Shapes > Subtract Front Shape.
now turn the invisible arrow layer to visible.
I think a great way to build this would be using a vector mask on a group, with the shape set to subtract — if the bottommost shape on a layer is set to subtract, it will remove the shape and fill to the edge of the canvas.
If you’d like to investigate further, here’s the PSD:
As you need both subtraction and preservation of one obejct's stroke I may advice the following:
1. Select the path of your arrow by Path Seletion Tool A and copy it. Now make this shape layer invisible.
2. Go to the star shape layer, pick the P or U tool, and pick the "Subtract Front Shape" path operation (the right dropdown in my screenshot below).
3. Now paste the copied arrow path to this star layer using the Subtractive mode. You'll instantly see the result of this operation and will be able to move and change both of your shapes within one layer.
4. Make the arrow shape layer visible now!
Please let me know whether it was helpful :)
Easiest method (using any image/layer on top of another):
1) Highlight the layer you want to use the shape from (e.g. round shape on top of another) in the Layers panel at bottom right
2) Click the Paths tab at top of this panel (right above your layers at bottom right)
3) Click Make Work Path from Selection button (bottom middle - shaped kind of like a compass)
4) Go back to your layers, and highlight the layer you want to pull from (note: you cannot use background layers for this - simply duplicate layer and hide background, if needed)
5) Go to Paths tab on this layer
6) Right-click on your Work Path and click Make Selection...
7) Click the Delete button on your keyboard
You now have your image!