I have a flower graphic I want visible only when it's over another specific object. I thought I could use source atop blend mode but that makes it visible as long as it's above anything else--I thought it would be selective of only things on its same layer, which is what I desired, but I see why it's the way it is now. The graphic is a UI component and so is currently on my highest layer.
Another acceptable solution would be to occlude part of the graphic, like so it only drew the portion of it below a certain Y level. but I'm not sure how to do that either. I am pretty much a total amateur when it comes to shaders so I'm still trying to figure this stuff out; there's similar effects I want to do that this second solution wouldn't really work for.
The graphic is the flower in the bottom left of this screenshot, but I want to put it at the top so it's centered on the nameplate, but only visible when it's in front of the backing graphic (and doesn't cover the gameplay area.)