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Lagometer

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File:Lagometer normal.png
Quake III lagometer during normal play.
File:Lagometer spike.png
Quake III lagometer showing lag spike.

A Lagometer is a display of network latency on an internet connection and of rendering by the client. Lagometers are commonly found in computer games or IRC where timing plays a large role. Quake and derived games commonly have them.

Advanced Lagometer consists of two lines - bottom and top. The bottom line advances one pixel per each snapshot received from server (by default they are being sent at 20 snapshots per second rate), while the top one advances one pixel per each frame that is rendered by client. Thus, if the machine framerate was 20 per second, both lines - top and bottom - would run at the same speed.

Bottom bars correspond to delay before sending a snapshot by a server and receiving it by a client (so called "ping"). The shorter the bar, the smaller the ping was. Red bars mean that the frame hasn't arrived on time, yellow ones - that the snapshot was suppressed to stay under the rate limit. Top bars can be drawn in blue or in yellow. While server shapshots are usually received at lower rate as the client framerate, the software interpolates position and movements until it gets an update from a server, when it adjusts own state accordingly. The height of upper bars is proportional to the interpolated time between snapshots received (so as long as they come regularly, it stays below the "zero line" and is drawn in blue), or - if snapshots stop to arrive on time - is extrapolated after the last snapshot expected (then bars crosse the "zero line" and are drawn in yellow). If those bars stay yellow for too long, client is forced to interpolate its frames beyond the "resonable level" and finally, when the snapshot arrives, the prediction turns out to hardly correspond to the server-side version, which results in a jerky, uncontinuous movement of scenery (obviously lowering the quality of gameplay).

Some games that use a "Lagometer" will simply remove a player from the game if their lag is too high.

Use the following console commands for the following games:

Game Console Key Command To Turn On Command To Turn Off Notes:
Call of Duty Tilde (~) cg_lagometer 1 cg_lagometer 0 Use 'seta % #' prior the command to make the command permanently.
Call of Duty: United Offensive Tilde (~) cg_lagometer 1 cg_lagometer 0 Use 'seta % #' prior the command to make the command permanently.
Call of Duty 2 Tilde (~) /cg_drawLagometer "1" /cg_drawLagometer "0" Use 'seta % #' prior the command to make the command permanently.
Call of Duty 4: Modern Warfare Tilde (~) /cg_drawLagometer "1" /cg_drawLagometer "0" Use 'seta % #' prior the command to make the command permanently.
Call of Duty: World at War Tilde (~) /cg_drawLagometer "1" /cg_drawLagometer "0" Use 'seta % #' prior the command to make the command permanently.
Call of Duty: Modern Warfare 2 N/A /drawLagometer "1" /drawLagometer "0" In game console is not avalaible.

Use config file (config_mp.cfg) to change default values. Use 'seta % #' prior the command to make the command permanently.

Call of Duty: Black Ops Tilde (~) /cg_drawLagometer "1" /cg_drawLagometer "0" Use 'seta % #' prior the command to make the command permanently.
Quake III Arena Tilde (~) /cg_lagometer 1 /cg_lagometer 0
Quake Live Tilde (~) /cg_lagometer 1 /cg_lagometer 0 cg_lagometer 2 to display the client ping estimation too
Tremulous Tilde (~) /seta cg_lagometer 1 /seta cg_lagometer 0
Star Trek: Elite Force II Tilde (~) cg_lagometer 1 cg_lagometer 0
Star Wars: Jedi Knight Tilde (~) /cg_lagometer 1 /cg_lagometer 0
Source-Engine Games Tilde (~) net_graph 1 net_graph 0 net_graph 2 or net_graph 3 for increased detail
Wolfenstein: Enemy Territory Tilde (~) /cg_lagometer 1 /cg_lagometer 0
Medal of Honor: Spearhead Tilde (~) cg_lagometer 1 cg_lagometer 0
Return To Castle Wolfenstein Tilde (~) /cg_lagometer 1 /cg_lagometer 0