graphicxtras.com > Combine Photoshop layers /set operations - intersect, subtract combine and exclude tutorial
The set / path operations are now combine, subtract etc - previously 'add to shape area' (if used in the top bar) and unite etc if used via the layer commands and combine etc from the properties.
You can combine Photoshop custom shape layers to create new shapes using the combine option for the live shape / custom shape layer. Multiple combinations can be made. Areas can also be subtracted / excluded / intersected (or subtract overlap etc - should be noted that the terminology has changed a few times and hopefully it won't change any time soon) to create a new shape. A single pack of shapes can be used to create millions of different and exciting designs.
If you are using the CC subscription then it may be easier to do all these set operations via Illustrator as you can then use the pathfinder panel to create ever more complex vector paths and also you can use many additional path tools such as VectorScribe and MirrorMe which are sadly not available to Adobe ® Photoshop ®.
The key thing to remember with the set operations is that the set operation works on the active shape so if there are no other shapes, the subtract option will just subtract from the entire document. If you add multiple shapes and use the combine option and then create a new shape layer and wish that to subtract, draw the shape and then set the option to subtract front shape.
The option to add new Photoshop shapes / subtract only appears when you are applying the designs as shape layers and paths but not fills. You can always add shapes via the fills by applying the design in the same color; you can also subtract from the shape by applying the designs in white, 'erasing' the shape - the intersect are not possible.
Use the set operations / subtract features to create distressed shapes in seconds. Personally, I generally use a vector application such as the fontlab tool or Adobe's own vector application to subtract and add shapes to a custom shape but if you are using Photoshop, these tools are still very powerful. Below you can see a mottled artwork with very small circles combined with a rectangle and the circles have been subtracted from the original rectangle all around the edge of the work as well as a small selection inside the rectangle. You can, of course, use any number of other vector layers with this combination and not just circles either so you could instead use rabbits or hens or screwdrivers or any other vector artwork in the the subtraction (circles just happen to be a little easier to use than those)
In the example below a rectangle was used again and instead of circles, lines have been used to scratch into the artwork, the lines being of different size as they are subtracted from the original rectangle work
It should be noted that sometimes it is referred to as combine and sometimes as unite depending on how you perform the operation. If done via the layer commands then it is unite and if done via the top bar of Photoshop it is combine (totally confusing but that is the way it currently stands though this set of functions has had a few changes over the years but the basics are still much the same - you want to stick two objects together !
The above has two circles combined - using the subtract option for the second circle. This can be done with any other artwork, of course, and not just circles and it can be repeated with the same artworks over and over to remove more and more from the original source artworks
The above is the intersect of two circles in PS. You don't have to use circles, of course, as it could be any custom shapes or rectangles etc.
You can then use the above petal artwork and then either create duplicates of that to perhaps create a flower artwork. Combinations / subtracts / intersections can be repeated over and over to create all kinds of new works and once you have finished, the work can then be defined as a new vector artwork and stored in the preset panel of PS as well as being added to the CC libraries and stored for future projects.
The above is the 'exclude' or subtract shapes path operation applied in Adobe ® Photoshop ® for the two circle layers
There is also, at the end of the set operations, a merge operation which turns the current combination into a regular shape (apart from a live one). Personally I find that I like to use the merge command more often than not as sometimes the result of a subtract or unite etc results in a very odd combination and that can generally be resolved by using the merge. The Merge option for the Photoshop combine layer shapes can be found by selecting the artwork and then going to the top option bar of Photoshop and going to the path / set path operations dropdown (combine, subtract etc). If it is not available then you will need to use the path selection tools or direct selection tools and then the merge should be available.
Photoshop shape with a subtraction - combine the two layers and then go to the layer menu and combine and subtract font
You can use the Photoshop shapes command to combine / unite a circle with one of the CSH designs (available on this site)
You can combine them by using a combination of unite and subtract
You can use the Photoshop shapes with multiple combine layers - the above was unite and then subtract and then subtract and then again. All kinds of complex designs can be created by using combinations though sometimes the result is not always as expected
You can repeat the subtraction multiple time - three subtracts of a circle has been used with a rectangle
Sometimes you will reach a point where the combine / unite etc of layers fails to work and then it is best use the merge command and then continue with the combine layers