Status bar

The status bar is displayed at the bottom of the screen during gameplay and shows the player's status. The status bar can be removed from the screen by maximising the viewport, although it is still visible in automap mode. In the very first Alpha version of Doom, the status bar framed the entire screen and was a visual representation of the player character's visor.

Doom Status Bar

 * AMMO:  The remaining ammo of the currently selected weapon.
 * HEALTH: The player's health. This can range from 0-200%. If it does reach 0% the player dies (unless he is in a sector of type 11).
 * ARMS:  The weapons currently possessed by the player (excepting the chainsaw and super shotgun).  These correspond to the keys pressed to activate them.
 * The player's face. This gives an immediate indicator of health and also reacts to events such as damage to the player. Specifically, if the player is hurt, the face turns and looks in the direction of the attack; a new weapon causes the face to grin briefly; and as health falls, the face becomes more beaten and bloodied. If the player has activated iddqd or the invulnerability cheat, or picks up the invulnerability powerup, the face has glowing golden eyes.
 * ARMOR: The player's armor level.  This can range from 0-200% (and, in versions of Doom prior to v1.2, an arbitrarily high number).
 * The keys possessed by the player.
 * Remaining and maximum ammo for all four ammunition types (bullets, shells, rockets and cells).

When "spy mode" is used in cooperative multiplayer games, the status bar remains that of the "spying" player.

In deathmatch mode, the ARMS display is replaced by a FRAG display showing the player's current score in the game. Furthermore, the background color of the player face is changed to match the player's uniform color.



Technical
The status bar code in the Doom source code is responsible not only for drawing the status bar, but also performs the palette special effects when injured or picking up items, and detects the entry of cheat codes.

Beta versions of Doom showed messages to the player and multiplayer chat being performed inside the status bar. This was moved to the Heads-up display; however, the Doom source includes leftover variables relating to "status bar chat" and the message display.

In the source code, ST_* is used as a prefix for files and functions associated with the status bar. This trend continues in the IWAD file, where graphic resources relating to the status bar begin with ST. The following resources are used for the status bar:


 * STBAR:       The main status bar graphic.
 * STGNUM0-9:   Small grey numbers used for weapons not yet possessed.
 * STTNUM0-9:   Large numbers, used for HEALTH, ARMOR</tt>, FRAGS</tt>, and AMMO</tt> displays.
 * STTMINUS-9:  Negative symbol for large text.
 * STTPRCNT:    Percent symbol for large text.
 * STYSNUM0-9:  Small yellow numbers to indicate weapons possessed (also used for total ammo display).
 * STKEYS0-5:   Icons used for the key display.
 * STDISK:      Floppy disk graphic used when accessing the disk.
 * STCDROM:     CD-ROM graphic used when accessing a CD-ROM.
 * STARMS:      The STBAR graphic includes a FRAGS</tt> box.  This graphic overwrites it with the ARMS</tt> box when not in deathmatch.  Early versions of Doom (pre 1.2) did not include this graphic, as the status bar did not include a FRAGS</tt> display.
 * STFB*:       Used as backgrounds for the player face in multiplayer mode.
 * STF*:        Player face graphics.

Heretic Status Bar

 * Life (or Kill in deathmatch)
 * Ammo
 * Keys
 * Artifacts' Inventory
 * Armor
 * Health Chain (equivalent to Doom's player face)

Hexen Status Bar

 * Life (or Kill in deathmatch)
 * Blue Mana (equivalent to ammo)
 * Green Mana
 * Artifacts' Inventory
 * Ultimate Weapon Pieces (Quietus, Wraithverge or Bloodscourge)
 * Armor Class (A.C.)
 * Health Chain