How to Knockout Shape Using Opacity Options? (AI 2020)

[whamalamaboom]

I wanted to use a shape as a clipping mask until I realized you can't invert clipping masks in AI and it's everything outside of the shape I need visible, not inside.

I know I can use pathfinder options to subtract the shape from the layer but that's destructive. I want to know how to do it using the knockout options under transparency and having to google every single thing I want to do in AI is eating up way too much time so I'm just asking for the exact steps here.

Do the two layers need to be grouped?

Which layer needs to be on top, the shape I'm using as a mask or the layer I want it knocked out of, or does it not matter?
Which layer needs the knockout option on it etc?

Thanks!

[Monika Gause]

This video explains opacity masks: https://helpx.adobe.com/illustrator/how-to/illustrator-opacity-masks-transparency.html

Mask needs to be on top when creating.

[whamalamaboom]

Thanks! I had already gone through Adobe's support videos and article but mine wasn't working so I wanted basic steps to just do what I wanted in case I missed something. I should have posted links but this is helpful for others who need it!

[Jacob Bugge · Accepted solution]

whamalamaboom,

In addition to the Opacity Mask way suggested by Monika, you can create a path (rectangle/ellipse/whatever) that is larger than all the artwork, then ShiftSelect the clipping mask shape, and then Ctrl/Cmd+8 or Pathfinder>Minus back, to create a Compound Path, and then use that Compound Path as the Clipping Path, just select everything and Ctrl/Cmd+7.

[whamalamaboom]

Thank you! I realized while messing around earlier that this is probably the better way to do it, just make the inverted shape to begin with and call it a day.

It's better than things getting confused with going into the individual opacities and grouping since there are some limitations with AI in selecting and modifying mixed attributes and other things that might make it a chore down the line if I did it any other way or had a ton of it in one project.

[Jacob Bugge]

whamalamaboom,

The Opacity Mask way is less cumbersome than you believe: what you can do to make the equivalent of an inverted Clipping Mask is to give the path(s) to form the hole(s) a black fill and no stroke, then (Group them if more than one (for Clipping Masks the corresponding non inverted paths need to be turned into a Compound Path to work, as you probably know) and) select everything and then Make the (Opacity) Mask with both Clip and Invert Mask unticked; or you can use a white fill and have Invert Mask unticked; if in doubt you can always toggle the Clip and Invert Mask options till you get it right.

As with so many things that can be done in multiple ways (often agreed upon to be everything), I believe that to a great extent it is a matter of what each of us simply enjoys, is used to, remembers best, finds least worst, or prefers in other ((dis)similar) ways.

[tzulah]

Jacob, this is the solution I have been hunting for, for SO LONG.  THANK YOU.  I needed to be able to make a group of objects not just transparent themselves, but show transparency through 2 other layers beneath them, non-destructively.  It felt so hard.

I don't think I've quite got my solution yet, as I can still see faint traces of the middle layers showing through for some reason but hopefully I can figure out where that is coming from.

[tzulah]

*Update:  The "faint traces" showing through were because my shapes were set to a blue colour, which was of course masking as a shade of grey.  I set it to black, and it's perfect!

[Jacob Bugge]

You are welcome, tzulah.

And thank you for sharing. The tiniest things matter with Opacity Masks.