Camera Facing to control shader mask

Hi All,

I have been looking for a solution to this in Unreal. I’ve done it in Maya and Blender so I know it must be possible I am just a novice at Unreal Shaders.

I would like to block on aspect of a shader from the Y direction. This is very similar to making a billboard material only the function drives a mask inside the shader and should not effect position. I need it to work with the camera orientation so the actor can move around the world and continue masking from the correct angle.

Hopefully not too vague, any help appreciated!