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Hitscan is a term is used mainly in computer games. It is a test to find out what can be hit by an in-game weapon (be it a melee weapon, or the projectile emitted by a firearm). Hitscan weapon is often used colloquially to refer to a projectile weapon which uses unmodified hitscan information to dictate whether or not it has hit its target -- deploying the weapon calls the hitscan function, and if an object is detected in the path of the projectile, a hit is registered. The effect is that these projectiles travel at infinite speed (a luxury of computers' non-analogue simulation of time) and have a linear trajectory -- a practical but very crude simulation of a bullet's speed and accuracy. Programmers need not use hitscan data in precisely this way when programming weapons.

Although hitscan weapons behave as described above, they can be given a more 'natural' appearance; for example, the assault rifle in Half-Life 2 calls a hitscan function in the middle of a 'blazing gun' animation, creating a small amount of lag between weapon deployment and the hitting of the target to better approximate real-life ballistics.

The origin of the term is uncertain.

Contents 1 Advantages 2 Disadvantages 3 Examples 4 Contrast to simulation

[edit] Advantages

The primary advantage is ease of use for programmers -- although bullets do not move at 'infinite speed' via perfectly straight trajectories in life, they move fast enough that a hitscan solution is 'good enough' to simulate their behaviour for the layman. It leaves the question of where a weapon has hit to just one function, streamlining the programming of weapons. It also readily ties cause (the player presses a 'fire' button, executing a hitscan function) to effect (the hitscan returns a result, the player sees the weapon's effect at that location). As such, it is usually used as a first model of shooting in (first) games programmers create.

There is also an advantage to the player, in that there is no need to lead the target (to aim slightly ahead of a moving target in order to compensate for the time it takes for the projectile to reach it).

[edit] Disadvantages

Visual representation of real bullet movement may cause confusion when it is applied to hitscan weapons -- a bullet may be seen to land behind a moving target when the hitscan has in fact already registered a hit on the target. Internet latency can compound this problem in online multiplayer gaming.

The hitscan method precludes realistic ballistics, as it cannot simulate a parabolic arc or atmospheric resistance (including wind direction).

[edit] Examples

• Insurgency: Modern Infantry Combat
• machinegun, shotguns and railgun in the Quake series.
• shock rifle (primary fire), minigun, sniper rifle and lightning gun in Unreal Tournament
• The Battle Rifle in Halo 2
• all firearms in Operation Flashpoint: Cold War Crisis, Delta Force, Red Faction and Armed Assault; as a result, the player must lead the target when firing from a very long distance.
• Battlefield 1942 and Battlefield Vietnam uses the hitscan method; their successors, Battlefield 2 and Battlefield 2142, dispensed with this.
• All projectile weapons of Team Fortress 2, minus rockets, grenade launchers, syringe guns, flaregun, arrows and baseballs.

• In some Third-Person Shooters, like the Max Payne and Hitman series, the firearms are also projectile weapons; the former (and games resembling it) takes advantage of this mechanic with its "bullet time" gameplay, where time is nominally slowed-down (revealing bullet trails and shockwaves) but the player can aim at normal speed.

[edit] Contrast to simulation

With advances in netcode and graphics processing, it became possible to simulate the ballistic nature of real-world firearms in multiplayer games using "projectile" models with extremely fast velocities, rather than relying on "hitscan" models. This adds elements of long-range deviation to what used to be "on-the-dot" targeting in many FPSs.