Best way to have mutual overlapping in Illustrator

Question

I'm using Illustrator CS5, and I'm trying to have two groups (with multiple paths in each) overlap properly.

On the top side, group A should overlap group B, but on the bottom side, group B should overlap group A.

The only solution I can come up with is to Knife-cut it in two, but then I get ugly cutting lines I can see in the result, even if I don't move the parts away from each other.

Any ideas?!

This will hopefully make it clear. I want the arm to be over the t-shirt at the bottom, but under the shirt at the top.

Answer 1

Add a clipping mask to the appropriate bit.

see ( http://help.adobe.com/en_US/Illustrator/14.0/WS714a382cdf7d304e7e07d0100196cbc5f-644aa.html )

Answer 2

In CS5 there is also the Shape Builder tool which is a quick & dirty version of the pathfinder (Be warned it does nasty things with variable stroked lines though)

Or you could use a commonly ignored feature which are opacity masks. They are a tad tricky to get accustomed to but are nearly as powerful as in photoshop. They also have the advantage that you would not need to create a big clipping mask enclosing everything: You could just make an object where you wish the layer to get transparent.

1. In the transparency Tab click the options button (right upper corner of the panel)
2. select Make opacity Mask
3. A new reactangle appears next to the preview of the object click it to be able to make the opacity mask objects.
4. You'd probably want to uncheck Clip
5. Draw in black where you want 100% transparency and white where full visible. Greys work too.
6. don't forget to click the "normal" object box (the left one in the tranparency tab) to stop editing the opacity mask.

btw this is a good method for transparency gradients. (Before the appereance palette got as powerful as in CS5)

I know this question was marked as answered but could not resist to provide these alternatives considering they might be more convenient in some cases.