I think I'am alone to find it's a problem or I'm alone to play really with Doom!
In old versions of Doomday engine we could configure a key to control "LOOKSPRING"
ON OR OFF when playing game. The reason why it is important is if you create
levels like me with Doom Builder when you play "REALLY" with Doom and not
only speak on forums you will understand. This problem is due to the
device used to play. If using Trackball, when you point with rocket
or any long distance arm, the target is far away and the shoot will
be too high or to low to shoot the target. Because the ball of the
trackball is used to move player and not to shoot. The only way
to control the VERTICAL angle of the arm is KEYBOARD key or the
WHEEL between the two strandard buttons. But those two trigger
are not precise and use a STEP by STEP Vertical movement. If
you move only one step, far away from player this result in
too high or too low calculate target.
In old Doomday engine the key EX: ALT could be programmed
to pass the VERTICAL arm setting to the BALL that was really
more precise and really FINE TUNE to point the target. When
pointed a far away target we had only to HOLD momentary the
ALT key, adjust the VERTICALY position of the arm and release
the key to restore the BALL for player movement.