# Hitscan

A hitscan in computer games, most commonly in first person shooters, is where the programming system determines where the gun/ object is pointing, casts out a ray in that direction when shot, for a certain range programmed into the system, and see if that ray comes in contact with any object in the line of fire. Hit scan is a term that could also be classified as “hit instantly” because it instantly hits the target when shot.

A projectile weapon which uses unmodified hitscan information to dictate whether or not it has hit its target is often called a hitscan weapon. Deploying the weapon calls the hitscan function, and if an object is detected in the path of the projectile, a hit is registered. Once it's determined if something was hit or not, the system will then give a damage output based on where the ray hit the object. Since the effect is immediate, the projectiles effectively travel at infinite speed and have a linear or otherwise simple trajectory—a practical approximation of a bullet's speed and accuracy over short distances.

You can modify the hitscan method by making some surfaces reflective, making the hitscan rays go on forever with no stop, or able to penetrate multiple objects at the same time in the same line. To improve the realism, programmers may use hitscan functions in slightly different ways; for example, applying a random perturbation to the calculated path to simulate inaccuracy.[1] As another example, the sub machine gun 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 primary advantage is the simplicity of the simulation, which uses relatively simple mathematics to calculate hits. Although bullets do not move at infinite speed via perfectly straight trajectories, they move fast enough that a hitscan solution is normally a reasonable approximation. It leaves the question of where a weapon has hit to just one function, streamlining the programming of weapons.

In terms of game design, it 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). While a simplified model of real world ballistics, it makes games more accessible in that there is no need to aim slightly ahead of a moving target in order to compensate for the time it takes for the projectile to reach it. Although less realistic this model requires no understanding of real weapon handling in order to play the game, and reinforces the intuitive understanding that whatever the reticle is placed over will be hit.