Line of sight, sometimes written line-of-sight or abbreviated to LoS, is the visibility (that is, who can see what) on the playing field in

wargames ''WarGames'' is a 1983 American science fiction techno-thriller film written by Lawrence Lasker and Walter F. Parkes and directed by John Badham. The film, which stars Matthew Broderick, Dabney Coleman, John Wood, and Ally Sheedy, follow ...

and some

role-playing game A role-playing game (sometimes spelled roleplaying game, RPG) is a game in which players assume the roles of characters in a fictional setting. Players take responsibility for acting out these roles within a narrative, either through literal ac ...

s (RPGs). Many abilities can only be used on entities within a character's line of sight. In some games, miniature figures are used to determine line of sight. Many wargames use counters to represent units and determine line of sight. A common technique is to hold a length of thread between two counters. If the thread, held straight, doesn't encounter any obstacles, the line of sight is valid. The first

computer game Video games, also known as computer games, are electronic games that involves interaction with a user interface or input device such as a joystick, controller, keyboard, or motion sensing device to generate visual feedback. This feedback ...

to implement line of sight graphics was ''

Dungeon A dungeon is a room or cell in which prisoners are held, especially underground. Dungeons are generally associated with medieval castles, though their association with torture probably belongs more to the Renaissance period. An oubliette (from ...

'', which was played on a

PDP-10 Digital Equipment Corporation (DEC)'s PDP-10, later marketed as the DECsystem-10, is a mainframe computer family manufactured beginning in 1966 and discontinued in 1983. 1970s models and beyond were marketed under the DECsystem-10 name, espec ...

mainframe computer A mainframe computer, informally called a mainframe or big iron, is a computer used primarily by large organizations for critical applications like bulk data processing for tasks such as censuses, industry and consumer statistics, enterprise ...

(1975).

Examples

tank A tank is an armoured fighting vehicle intended as a primary offensive weapon in front-line ground combat. Tank designs are a balance of heavy firepower, strong armour, and good battlefield mobility provided by tracks and a powerful ...

behind a tall hill would not be able to see an enemy tank on the other side of the hill. Therefore, the first tank does not have a line of sight to the enemy tank. Conversely, a squad of soldiers atop the hill may be able to see both tanks, though the tanks may not be able to see them (since the tank's upward line of sight is limited). In an RPG, players may not see doors, objects or monsters located around the corner in a

dungeon A dungeon is a room or cell in which prisoners are held, especially underground. Dungeons are generally associated with medieval castles, though their association with torture probably belongs more to the Renaissance period. An oubliette (from ...

. Line of sight is crucial to many types of

video game Video games, also known as computer games, are electronic games that involves interaction with a user interface or input device such as a joystick, controller, keyboard, or motion sensing device to generate visual feedback. This feedba ...

s, including, but not limited to,

first-person shooter First-person shooter (FPS) is a sub-genre of shooter video games centered on gun and other weapon-based combat in a first-person perspective, with the player experiencing the action through the eyes of the protagonist and controlling the p ...

strategy game A strategy game or strategic game is a game (e.g. a board game) in which the players' uncoerced, and often autonomous, decision-making skills have a high significance in determining the outcome. Almost all strategy games require internal decisi ...

stealth game A stealth game is a type of video game in which the player primarily uses ''stealth'' to avoid or overcome opponents. Games in the genre typically allow the player to remain undetected by hiding, sneaking, or using disguises. Some games allow th ...

s, and

role-playing video game A role-playing video game (commonly referred to as simply a role-playing game or RPG, as well as a computer role-playing game or CRPG) is a video game genre where the player controls the actions of a character (or several party members) immers ...

s. In simplistic games with a top-down perspective, such as

roguelike Roguelike (or rogue-like) is a subgenre of role-playing computer games traditionally characterized by a dungeon crawl through procedurally generated levels, turn-based gameplay, grid-based movement, and permanent death of the player charac ...

Bresenham's line algorithm Bresenham's line algorithm is a line drawing algorithm that determines the points of an ''n''-dimensional raster that should be selected in order to form a close approximation to a straight line between two points. It is commonly used to draw li ...

can be used to determine line of sight. In first person games such as battlefield and flight simulators an

implicit Implicit may refer to: Mathematics * Implicit function * Implicit function theorem * Implicit curve * Implicit surface * Implicit differential equation Other uses * Implicit assumption, in logic * Implicit-association test, in social psycholog ...

min/max kd-tree A min/max ''k''d-tree is a ''k''-d tree with two scalar values - a minimum and a maximum - assigned to its nodes. The minimum/maximum of an inner node is equal to the minimum/maximum of its children's minima/maxima. Construction Min/max ''k''d-tr ...

may be used to efficiently evaluate terrain line of sight queries. In some

live action role-playing game A live action role-playing game (LARP) is a form of role-playing game where the participants physically portray their characters.(Tychsen et al. 2006:255) "LARPs can be viewed as forming a distinct category of RPG because of two unique feature ...

s, such as

NERO International NERO International is a live action role-playing game (LARP) played in the United States. The NERO name originally was an acronym for "New England Role playing Organization", but the game has expanded well beyond its original New England roots and ...

, the line of sight is used as the duration for some spells and abilities. For example, a ''paralyze'' spell only lasts as long as the target remains within line of sight of the spell's caster. On the other hand, line of sight can be used offensively, like luring a player behind a pillar in order to set a trap - his teammate, being out of line of sight, won't be able to help out until he gets in LoS, which in turn takes time. This time is usually the key moment to strike and go for a kill, if said player falls in said trap. One algorithm for calculating 2-dimensional line of sight is given in the StraightEdge project.

References

{{video game gameplay Video game terminology