Editing Directional influence

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[[Image:DI-Melee.gif|thumb|The character [[name]]s show Ganondorf's [[Warlock Punch]] DI'd in different directions.]]

'''Directional influence''', usually abbreviated '''DI''', is the control the receiver of an attack has over his or her trajectory. Each attack sends its target in a particular direction; DI can be used to alter, but not completely change, this original trajectory. This change can be vital to surviving high power attacks such as [[Fox]]'s [[up smash]], and for escaping [[combo]]s, most importantly KO setups such as the [[space animal slayer]]. Perhaps one of DI's most useful applications is the ability to make the character move in a path that is as long as possible before crossing the [[blast line]]. "Good DI" usually occurs when a character is sent in a trajectory that creates the greatest distance between the character and the blast line, or one that will help the character recover back on stage. In most situations, angling towards the upper-left or upper-right corners will grant the greatest chance of surviving a high knockback attack. Conversely, "poor DI" (often informally referred to with some form of mockery towards a certain region/player, such as "West Coast DI", or "{{Sm|PatG}} DI" in ''Brawl'') occurs when the shortest distance between the character and the blast line is created, or the angle sends the player into a position they cannot recover from when they normally easily would, such as [[Semi-spike|down and away from the stage]]. Bad DI that results in a KO commonly occurs near the sides of the stage, when a character is hit diagonally while holding the [[Control Stick]] downward (commonly as a result of intentional [[fast falling]]), which sends them on a more horizontal trajectory, towards the closest blast line.

DI is executed by holding the Control Stick in any direction during [[freeze frames]] from an attack, before the character is launched. There are three types of directional influence: trajectory DI (almost always referred to as just "DI"), [[Smash DI]] (SDI), and [[Automatic Smash DI]] (ASDI). These last two function much differently from trajectory DI, and should not be confused with it.

[[File:Directions.png|thumb|A diagram of the directions ''Melee'' uses for DI, [[up special move]] angles, and numerous other things.]]

To determine the effective trajectory, the position of the Control Stick is read on the last frame of [[hitlag]]. [[ASDI]] is usually triggered by this as well. The highest deviation of trajectory is produced by directions perpendicular to the original knockback angle of the hitbox and amounts to approximately 18°, while also depending on how much the Control Stick is tilted in said direction; tilting it by a lesser amount will cause a weaker deviation. Holding directions that are parallel to the original angle will produce no survival DI at all. Because the possible DI angles are [[Media:Directions.png|not distributed equally]] (see diagram to the right), knockback angles within 17° of vertical or horizontal can be trajectory DI'd to a lesser degree, as no true correspondent perpendicular angle is available.

Survival DI consists of altering the knockback direction towards the upper corners of the screen so that more distance is required to reach the [[blast line]]s, effectively preventing a KO if the knockback was high enough to push the character into them with the original trajectory, but not enough to do so with the new trajectory created by the DI. Usually, if the attack's trajectory is almost entirely vertical, merely holding the Control Stick horizontally is needed, while if it is more horizontal, it must be held in a diagonally upward angle.

Because survival DI generally involves DIing up and in and combo DI generally involves DIing up and away, the combo game in ''Melee'' often comes down to a series of DI mixups. Using survival DI on a weak hit can lead to easy followups by the opponent, while using combo DI on a strong move can result in getting KOed at extremely low percents. This demanding need of mixing up DI is one of the main reasons for "poor DI" in high level ''Melee'' play, seen as a result of the player choosing the less favorable option out of pressure.

In ''Brawl'', DI operates identically to how it does in ''Melee''. However, one major change is that DI no longer works on knockback that does not cause [[tumbling]], regardless of the direction held on the Control Stick; this is most notable with throws that have low base knockback, such as {{SSBB|Pikachu}}'s [[down throw]]. This facilitates the execution of low percent combos, such as {{SSBB|Kirby}}'s Gonzo combo, but has also resulted in infamously stronger, inescapable [[chaingrab]]s and zero-to-deaths, namely the aforementioned Pikachu down throw and {{SSBB|Sheik}}'s [[forward tilt]] on the [[space animals]], and {{SSBB|King Dedede}}'s down throw on non-lightweight characters, which is made more problematic by the changes to [[stale-move negation]] causing moves' knockback to be decreased much more significantly if staled.

In ''Smash 4'', DI has been made only half as effective, reducing its maximum angle deviation to approximately 10°. Additionally, a second type of directional influence has been introduced, which alters the character's launch speed depending on the Control Stick's vertical position, so that holding upward increases their launch speed (and therefore how far they travel), and holding downward decreases it. This is known as '''launch speed influence''' ('''LSI''' for short), and was originally known as '''vectoring''' (name coined by {{sm|Strong Bad}}, who first published the Smashboards post), due to being initially believed to apply a vector to the character's knockback in any desired direction.<ref>[http://smashboards.com/threads/vectoring-the-replacement-to-directional-influence-in-smash-4.368780/ Smashboards - "Vectoring: The replacement to Directional Influence in Smash 4"]</ref>

LSI depends on how far the Control Stick is tilted in the appropriate vertical direction, multiplying a character's launch speed by x1.095 if tilted upward to the maximum and by x0.92 if tilted downward to the maximum. Like DI, LSI is determined on the last frame of [[hitlag]] right before the character is launched, and does not take effect on knockback that does not cause [[tumbling]]. This means that generally, moves with predominantly horizontal angles can have the player either pick between DIing high to aim themselves more vertically at the cost of being launched farther, or DIing low to reduce resulting knockback at the cost of ending up in a lower, less favorable position.

During the initial release of {{for3ds}}, LSI affected any angle with no restriction, giving it a significant effect on moves with largely vertical angles, while not incurring any significant compromise in DI due to the Control Stick already having to be held entirely vertically to achieve the full effect of LSI. More specifically, vertical finishers (like most [[up smash]]es) and [[meteor smash]]es could be survived for longer by holding down, while vertical combo moves (like most [[down throw]]s) would stop working earlier if the victim held up to be launched farther away from the attacker via LSI. Starting in patch [[1.0.4]], LSI has no effect if the launch angle is between 65° and 115°, or between 245° and 295°, preventing such moves from having their knockback altered by it and leaving DI as the only other, much less significant option against them.<ref>[https://twitter.com/Ruben_dal/status/820897784496852992 Ruben on Twitter: "In the meantime visuals to understand LSI: how it works, its conditions and multiplier formula"]</ref> However, this restriction takes DI into account rather than reading the base angle, which allows moves with angles differing from any of these thresholds by less than 10° (such as 74°) to still fall out of range and be affected by LSI, disproportionately so compared to moves with other launch angles. The most notable example of this fault is {{SSB4|Charizard}}'s {{mvsub|Charizard|SSB4|up throw}}, which can normally KO at around 125%, but due to its angle of 70°, DIing it at roughly 295° deviates it enough to get it out of the LSI-disabled range and therefore creates both optimal DI and LSI, rendering the move unable to KO until around 155%; this is in stark contrast to {{SSB4|Mewtwo}}'s {{mvsub|Mewtwo|SSB4|up throw}}, which due to its angle of 90°, is immune to LSI and barely affected by DI, only KOing 4% later with the latter in effect.