How to rotate/spin camera down after camera has been transformed?

Questions & Answers
1

My POV camera is attached to an object that can get hit by another object. When it gets hit the canera will spin in a random direction, like two weightless objects hitting each other...free rotation until drag stops it.

The Down key is mapped to spin the camera straight down. My problem is after it is hit, the down may not be Down anymore from the direction I'm looking. How do you fix this to always move Down from the direction I'm facing?

if(Input.GetKey("down")) { transform.Rotate(new Vector3(-1,0,0) * (Time.deltaTime * 180)); }

2

The code you posted will apply a relative rotation about the side axis, so if the object gets 'knocked out of alignment' due to a collision, the pitch may no longer be relative to the ground plane (as you've discovered).

To fix it, first I think you'll have to decide what the desired behavior is. In the meantime though I'll just mention one option, and that is an 'auto-leveling' function that gradually re-aligns the object, when necessary, so that the side vector is parallel to the ground plane.