Again, this is a rather trivial Illy skill, but with a program as robust and sometimes mystical as Illustrator, you can often get something to work and never know why. Other times you can't get something to work, something that seems like it makes a lot of sense, and all you are missing is a simple ‘bitt' of knowledge to rid you of your frustrations. In this quick tip, we will touch on the importance of compound paths, as opposed to groups, when applying a single gradient across multiple shapes in Illustrator.
In a Nutshell:
It may make sense to make a group when you want to apply a gradient across more than one shape, but Illustrator disagrees. In order to make a gradient stretch across more than one individual shape in Illustrator, you have to make a “compound path.”
A gradient applied to a “group” of shapes will apply the gradient to each shape individually, like this:
A gradient applied to a “compound path” will achieve the desired result, like this:
Do It Yourself:
1. Lets say that you have a few individual shapes/paths that you would like to apply a single gradient to, like below: (very simplified example)
2. Make sure that they are ungrouped, and that you can select them individually like this:
3. Now, select all of your shapes, and Control + Click (right click) on them somewhere to bring up your Options. Select “Make Compound Path.”
4. Now apply your gradient, and it will stretch across all of your shapes! Simple as that.