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Notes on SDI

Stealth Raptor

Smash Legend
Joined
Apr 18, 2006
Messages
15,088
Location
Kansas City, Kansas
Me and DeLux did some testing of SDI today and i would like to post what we found.

first off im going to explain some of what i know from my own personal testing. i would like to start off with a brief mention of vector analysis. nothing fancy its more for a visual aid to some of the mechanics. if you know what it is feel free to skip this, im gonna assume a lack of knowledge of it



when it comes to vectors, the best way to deal with them is to break them down into vertical and horizontal components that can be used for vector addition and such. as you can see in the picture, the red vector can be broken down into a horizontal (Blue) component and a vertical (Green) component. there are formulas that allow you to get the magnitude and angle and such from this, but thats unimportant for SDI.


NOW when you SDI, the game seems to look at the components to determine if to SDI or not. if there is a new component in any direction, it will input the SDI in the direction of the control stick.

lets say someone is going to HCDI a hit, starting straight left and going clockwise to straight right. first left is hit, and a new vector to the left is seen by the game. it says yes to SDI, and it goes to the left. lets say on the next frame, the control stick is up-left. the game sees two components, a left and up component. the left component is old so it ignores it, but the up input is new, so it triggers SDI, and you SDI to the up-left (note it isnt up but up-left. the components that i talk about do not influence SDI, they just sorta serve as a yes/no to whether or not to do it). one frame later, your control stick is straight up, leaving only an up vector. as there are no new component vectors, the game triggers a no, and no SDI is visible. on the next frame, the control stick is up-right. the game sees a new component to the right, and triggers a SDI to the up right. this continues down to right, where as no new components are made there is no SDI. this behavior was seen by me in frame advance and by what me and lux did tonight. i would also like to point out that when it goes from straight up/down/left/right to a diagnol, that diagnol input could be in any direction between the cardinal directions, it doesnt have to be straight in the diagnol, which means more or less that even though there are a lot of possible SDI directions, the game really only registers eight seperate directions, the four main directions and each quadrant between the four main directions

this is more or less how it sees SDI. note if SDI is done by the tap method, there is at least one frame of no input so any tap SDI is still registered as it goes from no vectors to one vector in whatever direction you tap.


now lux looked at the data K Prime collected in regards to holding the control stick in a direction and tapping the cstick (ISSDI and grab mashing) and was thinking it could be used for SDI. what we found is that if you hold a direction and tap the cstick once, it inputs two very rapid SDI inputs, seperated presumably by one frame (wasnt frame tested, didnt have the codeset + inconsistancy of cstick in frame advance) both in the direction that the cstick was hit. note these must be at least ninety degrees apart ie both must have at least one vector component different from each other to trigger the SDI. if the cstick is tapped in the same direction as the control stick is held nothing will happen.

a quick summary of various SDI:

single tap- one SDI per input of tapping the control stick or cstick, probably wont get more then one off except large hitlag
double tap- two SDI inputs per tapping of the cstick + control stick slightly offset. probably wont get off more then a single double tap except in large hitlag
QCDI- rotating the control stick in a quarter circle. as its only nintey degress there will only ever be two new vectors so only two SDI inputs are technically possible (if you happen to go slightly beyond ninety degrees you may get a third input depending on starting point)
HCDI- rotating the control stick in a half circle. This will only give you a max of three SDI inputs (if you go slightly beyond a half circle you may get four inputs depending on starting location but at that point you are SDI'ing the opposite direction so it wont help)
DSDI- holding a direction on the control stick and tapping the cstick. this gives two SDI inputs seperated by a frame. can be done a little faster then double tap as its a bit easier to tap one hand really fast then coordinate both

the DSDI has a lot of potential, after we looked into this DeLux was doing some crazy SDI shenanigans almost immediately in our matches

if you have any questions please ask, i can ramble at times so i may have been a bit confusing.
 

DeLux

Player that used to be Lux
Joined
Jun 3, 2010
Messages
9,302
Don't be hating KPrime

I literally yell "Kprime is broken" every time I grab someone now. Share the wealth :)
 

KayLo!

Smarter than your average wabbit.
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Philadelphia, PA
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Only skimmed so far, but this looks pretty sick. More people need to abuse SDI!
 

Pikabunz

Smash Hero
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I just don't like people naming things after themselves, especially if it's a concept that's already known/used. I honestly hate seeing people call that fast grab break method the "kprime break method" or whatever. I don't even think it's THAT useful for me to be credited for it, but I still think it's the fastest way to mash. The whole double stick thing isn't really my discovery. I first learned about it from Yika. He's the real genius!
 

DeLux

Player that used to be Lux
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Jun 3, 2010
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But how are we to build are legacies if not naming everything after ourselves? :) :) :)

Actually, I was saying in Skype how ironic it would be if named after me because I would never use it that much since SDI separates ICs all the time unintentionally
 

Yikarur

Smash Master
Joined
May 29, 2007
Messages
4,595
Location
Germany
I first learned about it from Yika. He's the real genius!

I get credit once in my lifetime, I can't believe it <3


and the OP Explanation is so terrible (no offense but it is really hard to read through it)

The Game has four directions for SDI. Left Right Down and Up.
We all know already that the controlstick is coded for wiimote (WHYEVER LOL).
If you press in the upper left corner of your controlstick the game does not read "upper left", it reads "up+left" because the (wiimote has no upper left) which are 2 SDI inputs in one frame.
Your vector explanation makes sense but is just not necessary. We can just explain everything with what I just said.
if you hit the upper left corner you do "up+left" if you slide to up then it doesn't register "up" because you already pressed it before, the game reads this as "holding one direction" and SDI is inputted by inputting a new direction without holding.
interesting: it seems if you hit the Controlstick between "up+left" and "up" (in the 16th) the game doesn't think anylonger you input any controlstick direction for SDI and if you hit "up+left" afterwards again you get the full two inputs. ("seems" because I tested this in frame advance and I can't find a better explanation for this event)


the Double SDI occurs because the C-lstick input ignores the Control Stick input for one frame and then the controlstick inputs gets it's effect back and the game reads it like "smashing" the stick because the input is new again. (works with dashing too, hold attack and walk by holding the stick in one direction and then tap up on the controlstick, you'll dash)


and this is of course Yika SDI :awesome: (not)
 

KayLo!

Smarter than your average wabbit.
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What do you mean by "in the 16th"? Is that just a fancy way of saying up-up-left? (Or NNE if picturing it as a compass makes it easier for people.)
 

Stealth Raptor

Smash Legend
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Apr 18, 2006
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15,088
Location
Kansas City, Kansas
i know its terrible i have a tendancy to ramble and im not the best at explaining, but all i said is very much true

also on your interesting note, i noted this as well and i surmised that the game thought the input was close enough to up to count it as up. this seemed to be present in all the directions
 

DeLux

Player that used to be Lux
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I thought they were both fine explanations.
 

InnocentRoad

Smash Cadet
Joined
Aug 26, 2008
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32
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Japan
SDI stick image


SDI rule
1. The input two or more times succeeds if the neutral is placed.
2. SDI is only effective once of the amount when the same element of the stick is consecutive.
(for instance, (D,R)->(R) is Once.)
3. SDI is effective twice of the amount when the different element of the stick is consecutive.
(for instance, (R)->(U,R) is Twice.)


Best SDI can be led when thinking from the rule.
When you want to do SDI to the right four times quickly...
ControlStick(R)->ControlStick(U,R)->C-Stick(D,R)(->ControlStick(U,R))
(The second (U,R) is automatic , because C-Stick was input.)


DSDI
e.g. (FALSE)
|1F| // C-stick (R)
|2F| // Control Stick (R)
(R) is consecutive in the first frame and the following frame.
So it becomes worth of SDI once.

e.g. (TRUE)
|1F| // C-stick (R)
|2F| // None
|3F| // Control Stick (R)
(R) is not consecutive.
So it becomes worth of SDI twice.
 

GimR

GimR, Co-Founder of VGBootCamp
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ahh, I knew something was up. the only thing is, when most people half circle DI, they don't do it frame perfect so they actually get better SDI from it. Also, this is why I usually go from one diagonal to another when I SDI because I noticed it didn't ignore SDI as much like Half circle DI does some times.


Lastly, would the best SDI in the world be something like this(If you're trying to get to the right)?


  1. Input: up+right
  2. Skip Frame(But keep up+right held)
  3. Input: C-stick Down+right
  4. skip frame let go of everything
  5. repeat
 

DeLux

Player that used to be Lux
Joined
Jun 3, 2010
Messages
9,302
ahh, I knew something was up. the only thing is, when most people half circle DI, they don't do it frame perfect so they actually get better SDI from it. Also, this is why I usually go from one diagonal to another when I SDI because I noticed it didn't ignore SDI as much like Half circle DI does some times.


Lastly, would the best SDI in the world be something like this(If you're trying to get to the right)?


  1. Input: up+right
  2. Skip Frame(But keep up+right held)
  3. Input: C-stick Down+right
  4. skip frame let go of everything
  5. repeat
No

You would ideally on step two tap the cstick, the next frame reneutral ONLY the cstick, and the following frame tap your cstick again, reneutral the cstick, retap cstick, etc.
 

GimR

GimR, Co-Founder of VGBootCamp
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ah okay, I know your first post probably already explains this, but, does the DSDI ignore the 4 directions control stick rule where SDI inputs are ignored?
 

DeLux

Player that used to be Lux
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Jun 3, 2010
Messages
9,302
There's a more refined explanation and video in the Dual Stick thread in the lab GIMR
 
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