Mask shapes canceling each other out when overlapped...

[rafael]

I have two layers in a group. Bottom layer has multiple shapes in it that I want to use to mask the layer above it. It works as expected except where the shapes in the mask overlap. How do I fix this?

[Greenlaw]

Using the standard masking technique, it seems to work here. For example, I have two overlapping circles in one layer, and a single circle as a mask in another:



Are you doing anything unusual with the shapes? Like, were the overlapping shapes created as a single shape? That can cause interesting (and sometimes useful) boolean effects...or undesirable effects when it's done unintentionally.

Can you post an example project?

[hayasidist]

yeah - it sounds to me as though the "shapes" in the layer used as a mask are not separate Shapes in the Moho sense of the word. As Greenlaw says, it's possible to create several closed Paths that are treated as one Shape - this is how freehand behaves if you have autofill on. Take a look at the mask layer on its own. If there are "holes" in it then this is likely what has happened. More about this in Tutorial 2.2.
hope that's helpful!

[Greenlaw]

To further illustrate what Paul and I are talking about, here's the same two overlapping circles used to create a single shape instead of two separate shapes.



Is this the effect you're talking about? This is expected when you create shapes this way.

[Greenlaw]

Here's an example of where the boolean effect can be useful.

Two versions of a 'face' have been created using the three circular paths seen in the middle:



On the left side, the paths create three separate shapes, each filled with white.

On the right, however, they create a single shape, and the overlapping 'eye' circles punch holes in the 'head' circle. Using this technique, you can place irises in a separate layer behind the face and they will get masked without using a mask layer.



(Thanks to Victor Paredes for showing me this handy trick!)

[rafael]

were the overlapping shapes created as a single shape? That can cause interesting (and sometimes useful) boolean effects...or undesirable effects when it's done unintentionally.

100% what the issue was. Thanks for the help and eye trick, I'll definitely be using that at some point!