Selective roundness on corners in rectangular shape layer?

[VFXbear]

I'm designing a broadcast package that uses animated text background rectangular shapes (resized proportionally to text via SourceRectAtTime) with 3 rounded corners and 1 rectangular corner (see attached example).
I'm currently achieving the effect with 2 layers, and a linking of Anchor Points via expressions, BUT due to the antialiasing, you can slightly see a "shimmer" where the little rectangle (TopLeft) overlaps with the underlaying rounded shape.



It would be great to have the option under Shape > Rectangle > Roundness to have either all corners affected simultaneously or selectively (same style option as in the Transform effect > Scale (Uniform Scale or Y/X separately), so one could define Roundness to be applied via tickboxes for TopLeft, TopRight, BottomLeft, BottomRight as needed.
Or maybe like with the Convert Vertex tool : click/toggle the corners that are affected by the Roundness parameter, which could then apply to all types of shapes, not just the Rectangle.

Is there a way to fix this?  And could this be implemented in a future update of AE?

[Roland Kahlenberg · Accepted solution]

I've not tried this but it fits the description - https://elementsupply.co/products/utilities/roundy_box

[VFXbear]

WOW !! That looks exactly like what I need!
Gonna give it a try right now.  Fingers crossed ...
Thanks!!

[VFXbear]

Just tried it, and it does exactly what I need, and more!!

thanks again!!

[Roland Kahlenberg]

Thanks for reporting back with your results.