Materials How to: if Base output has blue color - then inverse the blue, otherwise do nothing?

[XxNotAGamerxX]

Does anyone know the Material logic to have 2 input paths, 1 output?
Or is it even possible?

The code I posted is incomplete because I do not understand how the nodes in the red box work, thus my question.

• What do I put as [Value] in the Switch node?
  I need 2 inputs A & B, a 3rd for off/on, no/yes, and an output based on the no/yes result.
  Closeup pic (full pic is in OP):
  
  

I got the idea from this pic, using Distance node as a measurement of the difference between [Base output] and [the color I want to detect]:

how can I remove background color from a material?

[110452-c.png] Thank u very much! I found a solution on github: GitHub - Tolc/Unreal-UMG-3DObjectInWidget: A simple Unreal Engine 4 project (precisely 4.7.4) showing how to render a 3D object/mesh in a UMG widget.. But this solution generates noticeable aliasing，how can I solve this problem? Thank u.