ST-CS-10-339-75
March 2002

2.  Hitbox Distortion  (U)

Counter-Strike has a history of programming errors leading to distorted hitboxes. The player models are stored in .mdl files (player model files) which are in the cstrike/models directory.

These files contain correct and accurate data. However, Counter-Strike, once it has read this data in, performs considerable processing before finally using the data. The bugs in this processing lead to the actual positioning of hit boxes in real game play differing from that shown in the player model files.

In other words, the hitbox images shown in the previous page are basically a lie; they are what ought to be, rather than what is.

Hit box distortion was recognized as a major problem by the Counter-Strike development team during version 1.1 and considerable work was put into fixing matters.

Unfortunately, Counter-Strike 1.3 retains some hit box distortion problems. These are significantly less serious than in the previous version - in particular, wall-effect (head hit box disappearing if the target player is crouched and a wall is in the line of sight of the weapon being aimed at him) has been fixed.

Hit box distortion errors fall into two classes; those associated with holding a particular weapon (for example, in the first release of CS 1.1, a player with an AUG had no leg hit boxes while standing) and those which are always present, regardless of the weapon held.

Player model files contain positioning information for every possible player movement - walking, crouching, running, swimming, holding a rifle, firing a rifle, holding a grenade, etc.

The mp5, both shotguns, M249 machine gun, AK47, dual berettes, knife and grenades have their own individual position information. All the other weapons use one of two generic weapon-holding sets of position information. (This is why in 1.1 the dual berettes had a unique and particular error; if the holder was crouched, his head box was exaggerated vertically by a factor of four).

The authors have elected to minimize research into this area since version 1.4 is due very soon, and the large number of positions to be checked make this a major effort. However, the following video footage demonstrates hit box distortion in version 1.3.

Here we see the chest and shoulder hit boxes extending vertically by a significant distance on a player crouched with an AWP. Note that the horizontal crosshair bars are above the top of the player's helmet. Comparing the location of the hit with the player model hitbox overlay, it is clear this is not supposed to be a hitbox.

This vertical extension also applies to the headbox and so is likely to contribute to the high frequency of headshots in version 1.3.