I'm working in AR and as such, I want to create little patches of dirt on a plane that can blend with the users "real world". I simply want to have a plane shaped mesh as shown in the screenshots and have the edges be faded or feathered to transparency.
Current
What I Want
How can I achieve this? A Fresnel affect almost does what I want, but its tied to view perspective, which does not accomplish what I'm looking for.
Thanks in advance.