Editing Smash directional influence

The mechanics of SDI operate by shifting the character by a vector determined by the control stick. SDI is applied on every frame a control stick vector of sufficient length is input, in a new direction on either horizontal or vertical axis. As a result, repeatedly tapping in one direction will move the character much farther than simply holding the stick in that direction. In addition, because diagonals have both horizontal and vertical components, changing from an orthogonal position to an adjacent diagonal one will generate a new SDI input, while changing from a diagonal position to an adjacent orthogonal one will not. This results in a technique called '''quarter-circle DI''', which involves quickly rotating the stick between two orthogonal positions for increased distance. Quarter-circle DI was introduced to the United States by Japanese smasher {{Sm|Captain Jack}} and was once known as Japanese DI.

In ''Brawl'', the C-stick can assist in SDI. So-called '''double-stick SDI''' utilizes the C-stick's ability to override the control stick by holding one of the sticks in one direction and utilizing quarter-stick DI with the other.

Whenever a character is hit on the ground by an attack that does not lift them off it, such as a weak [[meteor smash]] or move that launches at the [[Sakurai angle]], they can only leave ground horizontally, not vertically. This prevents them from SDIing upward and going airborne before getting launched by the attack, potentially allowing them to immediately land and cancel [[hitstun]]. When grounded, the horizontal component of a diagonal SDI vector still moves the character, only vertical component is negated. Consequently, quarter circle SDI and other methods to perform multiple SDI inputs still work. In ''Ultimate'' when hit with a move that will lift the victim off the ground, it is possible to SDI upwards only if the first SDI input is made on exactly frame 2 of hitlag, and it is in an upwards direction. Doing so lifts the opponent off the ground during hitlag, allowing for further upwards SDI inputs to be made. Notably, this allows opponents to jump out of fast hitting moves such as {{SSBU|Ryu}}'s down tilt which would otherwise force a landing during hitstun, before hitting the ground, as they will be launched from higher up, and thus the hitstun will end before they land. However, due to the frame perfect timing required, which also demands a correct prediction of what move will hit the victim and on what frame, this has little to no utility in realistic circumstances. The opponent can still SDI off the grounds when hit by an [[electric]] attack.

'''Automatic smash directional influence''' ('''ASDI''' for short) is a weaker variant of SDI. Once a character's hitlag is over, they shift slightly in whatever direction the control stick is currently held, by a shorter distance than an SDI input. If the C-stick is also being held in a direction, it will override the control stick's input, allowing the player to [[DI]] in another direction simultaneously. ASDI is significantly less useful than regular SDI and is generally ignored, as any stick position during this time is likely to be attempted at regular DI. In ''[[Super Smash Bros. Melee]]'', however, it is an important factor in [[crouch canceling]], as well as a powerful [[neutral game|neutral]] option; this is because the air-to-ground rule of '''forbidden SDI''' does not apply to ASDI, letting a character land on the ground immediately, a technique known as '''ASDI-down'''. If the character wasn't knocked down, the landing cancels hitstun, and thus allows them to retaliate against attacks much quicker than usual. It is often used in place of crouch cancelling against moves that have the [[Sakurai Angle]], such as the weak hit of Marth's [[Dolphin Slash]], as at specific percents they are impossible to crouch cancel. It is additionally key in utilizing techniques like [[Tech#Rolling_tech|Amsah techs]] and [[Slideoff DI]], which use ASDI-down to create tech scenarios and escape combos respectively.

*ASDI has been removed almost entirely, only applicable on moves with an electric, [[paralyze]], or [[crumple]] effect, and a special attack effect only used for [[Kazuya (SSBU)|Kazuya's]] 10-hit combo, further limiting its application. Oddly enough, it now applies twice against moves with these effects. It also oddly still seems to apply for [[Final Edge]].