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> I'm trying to create a mask that will hollow out the center of a circle and I can't seem to align the circular mask perfectly within the original circle. Is there a way to automatically align a mask to its parent object?
If I needed to center something within a circle, I'd turn on the rulers or grid and use them to find the center of the circle and then draw the mask from the center. When you draw a circular mask, holding Ctrl (Windows) or Command (Mac OS) will make the circle scale around the center as you drag. See "Create a shape or mask by drawing with shape tools".
> For that matter, I'm a beginner and am wondering about any alignment options in AE period.
See this page of After Effects Help:
You can find things like this with the search feature built into After Effects. (Look in the upper-right corner of the application window.) For example:
If you're new to After Effects, then I strongly recommend that you start here:
It's nice to now have the align tools, but it still doesn't help me align the mask within the object itself. I can't seem to find the actual coordinates of the mask, either.
Here's what I'd do.
Draw your circular mask, then select the mask in the timeline and press Ctrl/Cmnd + D to duplicate it. Set the duplicate to subtract, then press the M key twice to reveal Mask Expansion and set the value to a negative number. It will take you about 10 seconds and the masks will be perfectly aligned.
You can also use mask expansion on a rectangular to get rounded corners. IOW, draw a rectangular mask, set Expansion to 10 and you have a rectangular mask with 10 pixel radius rounded corners.
The last other option is to select our mask, duplicate it, then double click on the duplicate and hold down the Shift + Cmnd/Ctrl key and drag it to the new size you want. Hope this helps.
BTW, there are no coordinates for a mask that can be extracted. That's why expressions won't work on masks.
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I can't seem to find the actual coordinates of the mask, either.
Ctrl+Shift+M opens up the mask coordinates dialog which tells you the bounding box coordinates. That's all you ever get in Ae. It doesn't provide access to the mask vertices. That aside, you ar simply using the wrong tools and workflows. you could have done this in 3 seconds using shape layers or the classic Circle effect...
Thank you! I actually figured it out last night before your response. The correct answer is definitely using the bounding boxes!
Are those values the amount of pixels away from the center of the mask circle?
Also, how would I add 3D depth to a shape layer? (i.e. If I rotate the shape in 3D around the Y-axis, I want to see some "thickness" or depth in the shape.)
> Also, how would I add 3D depth to a shape layer? (i.e. If I rotate the shape in 3D around the Y-axis, I want to see some "thickness" or depth in the shape.)
This After Effects Community Help search for 'extrude' pulls up several answers regarding several techniques.
You might want to check out Freeform, too.