Occlusion mask at player location rotated towards the camera

Hey,
I’m trying to achieve a see-through effect when objects get between the player character and the camera in a top-down setting. I’ve managed to get it working well via the opacity mask when the character is at the centre of camera view, but I’d like the effect to always face the camera even if it’s not currently looking at the character directly.

Here’s what I have:

This is how it appears when the camera is not facing the character:

not_facing

How can I integrate the camera facing functionality into this material function?