Alpha mask for click?

Unity Engine
1

Is there any way to natively make a click only go through where the alpha isn’t a transparent value?

For example, I have sharp angles on a button, and want anything outside the drawn border to not interact with anything. So… if you hover over a transparent area, to not highlight, and so forth. (using unity 5 UI)

2

The RaycastMask effect in the UI Extensions repo does exactly that (link in sig)
This effect will filter raycast hits based on the alpha of the masked image.