uh, yes(?)
The maskout would start where the blade enters, and finish at the end of the body, mask in would be every where else. We only did masking with UI. so always had hard edges.
We had a star, shape, which would slowly fill up:
Loading Image
We a red square which would scale from Y=0, until the star is full
A star shaped mesh (bounding box)
And a Star outline.
Anything within the bounding box renders, anything outside does not. I.e. you get the above, even though the red square is also outside of the star
I will maybe say you should explore orther options before doing masking
