Screen shake when shooting

Where can i change the value?

self.punchangle_x

By using this on, let's say, "i get hit", can i have the same effect?

Yes. Punchangle is a field that is added to the player angles and gradually faded back to '0 0 0' by the engine. Very large punchangles look very silly since they can reveal bits of the viewmodel that are not supposed to be seen.

Also, you can't alter the rate punchangle fades back in QC (well... without re-implementing it in QC).

I'm wondering if the way it slowly fades punchangles back to '0 0 0' can be used to fade fog values from one to another...

perhaps, if (fog_r < desired_fog_r)
fog_r = fog_r +1
probably not how punchangles work, just going a bit off topic haha, sorry.

I'm wondering if the way it slowly fades punchangles back to '0 0 0' can be used to fade fog values from one to another...

perhaps, if (fog_r < desired_fog_r)
fog_r = fog_r +1
probably not how punchangles work, just going a bit off topic haha, sorry.

That would be very framerate dependant.

yeah, you'd want something more along the lines of
((endFogTime - currentTime) / fogDuration) * fogAmount to get a proper framerate independant fade.