[Smash Bros.] Directional Influence (DI)

[Flint]

Directional influence, abbreviated D-I, is the control the receiver of an attack has over his or her trajectory. Each attack sends its target in a particular direction, depending on the attack itself and on the target's weight and falling speed; 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 combos such as Jigglypuff's up-throw to rest combo on fast-fallers (see 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" 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 would normally easily recover from, such as down and away from the stage. Bad DI that results in a death 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 fastfalling), which sends them on a more horizontal trajectory, towards the closest blast line.
The player can DI by pressing the control stick in any direction during or just after being hit by an attack.

There are two types of directional influence: Trajectory/Survival DI (almost always referred to as just "DI") and Smash DI. Smash DI functions much differently from Survival DI, and should not be confused with it.

DI in Super Smash Bros.

Directional influence does not exist in the original Super Smash Bros.; only smash directional influence does. This contributes to the ease of combos in said game.

DI in Super Smash Bros. Melee and Brawl

Survival DI: Survival DI alters the knockback direction towards the upper corners of the screen so that blast zones are escaped, preventing a kill provided that the knockback wasn't too high.

Smash DI: The topic of Smash DI is something that can be extremely elaborate and I'm planning on making a future post solely on the topic on Smash DI. For the sake of this post, I'll explain the basics. SDI is a mechanic that allows players to slightly alter their position during the freeze frames of being hit by an attack. Tapping the analog stick in any direction during freeze frames will slightly move their character in that direction, allowing them to potentially escape multi-hit moves or certain combos. SDI can also be used to move into a wall or ceiling in order to tech near-instantly or to increase the distance from the blast line that the attack is about to send them towards. Despite its near-identical name, SDI is not a subtype of directional influence (or DI), but a different mechanic altogether that is performable under the same circumstances. The major difference is that, while DI changes the trajectory a character is launched in, SDI changes a character's position before launch.

DI in Smash 4

Upon the initial release of Super Smash Bros. for Nintendo 3DS, directional influence acted in a very different way. Instead of altering the angle of knockback by a limited amount, the player inputs a vector that is added to the vector of knockback. As a result, instead of surviving longer by DI'ing perpendicular to an attack, players survive longer by DI'ing directly against the attack, and can also escape combos by DI'ing in sync with the attack. This technique is commonly known as "Vectoring", and this overall allowed characters to survive significantly longer than they would with normal DI, while making combos much more difficult to pull off, as vectoring allowed opponents to frequently be hit too far to successfully followup. The name was coined by 'Strong Bad', who first published the discussing this mechanic. Version 1.0.4 of the 3DS version changed the DI system again. Horizontal vectoring is still present, but vertical DI is reverted to its Melee/Brawl incarnation.

If you have any criticisms, questions, or confusions I'd like to hear them.