soften edges of wall/ceiling/floor planes when `entity.plane.opacity = false`

[michaelthatsit]

As discussed, I'd like to soften the edges of the plane anchors when opacity is disabled, such that it is a slow transition from seeing the physical environment to seeing the virtual environment behind it.

This when 2 connected planes have opacity disabled there should be not gradient where they connect, such the connected edge is not visible.

Here's a video illustrating the gradient I'm thinking of:

https://www.youtube.com/watch?v=scBY3cVyeyA

[michaelthatsit]

And some images. The red is indicates the virtual content, not the expected color. Tried to illustrate a gradient.

and the expected behavior if two connected planes are unoccluded.

[michaelthatsit]

Maybe start with rounding the edges and then jump to the gradient.