Screenspace to Worldspace conversion with isometric angle?

Unity Engine
1

How would one do this? I am completely lost.
This is all I have.

public static Vector3 Cursor()
    {
        Vector3 v = Input.mousePosition;
        Vector3 w = Camera.main.ScreenToWorldPoint(v);
        w.y=1;
        return w;
    }

The above code only works at 90 degree’s facing down which makes sense because when you tilt the camera 45 degree’s you are adding distance on one side.

So my question is that to make this work for 45 degree’s what would I have to do? I have a feeling there’s trigonometry somewhere involved but I am not sure.

Thanks,

2

Anyone have any ideas?