I want the "fill" area of the circles to be transparent, so the background of my document can show through.
— Dunstan Orchard, designer at Flickr
First thing that came to my mind was that one of the Pathfinder options would be the obvious answer. The only question for me was "which option of the Pathfinder do I need?". You see, I totally love the power of the Pathfinder, but for some reason, there are a few in there that keeps me stumped what their function is. The ones that confuse me are in the second row. They are the destructive ones: Divide, Trim and Merge.
What I want as a result, is turn the black strokes into fills, and the white areas of the shape into transparent gaps. So how do we get rid of all the overlapping paths of the circles, without destroying the original shape of the nucleus, and have all the black lines still in tact? Here is how…
- Our starting illustration consists of shapes (in our example, circles) in stacking order.
- Select the whole shape and choose the Trim option from the Pathfinder (2nd row)
- Now the paths are linked like we want them to, but the stroke is gone. Remove the white fill, and give the shape back its black stroke.
- Turn the stroke into a fill: go to Object > Path > Outline Stroke
Now you have a perfect shape you can copy and paste into Photoshop as a Shape Layer and play with it. Let the background show through, or use the shape as a mask like I did in my example. Shape Layers are great to work with in Photoshop as you keep things resizable and flexible. I always try to use them where I can.
The Live Paint method
Like with many things, there are multiple ways to achieve the same result. This other method with the Live Paint feature is a hat tip by oVan:
- Select the whole shape and choose Object > Live Paint > Make
- With the object selected, give it a transparent fill
- Go to Object > Live Paint > Expand
- Go to Object > Path > Outline Stroke