Launch Speed Influence
Ruben - May 1, 2017I have been getting this question a lot, and since I haven't made a proper video (because I'm bad at making one lol) it would be better to post a full explanation about it here.
First, LSI (Launch Speed Influence) was named like that because of two reasons:
- It affects Launch Speed as a multiplier
- It works similarly to DI and it’s related to it
This mechanic is what most people called “vectoring” however it’s very definition was wrong since it often referred to increase knockback when holding the stick parallel to the launch angle, which is not how it works in-game.
So how does LSI work? Like DI, it uses the stick direction held on the last frame of hitlag and it is required to cause tumble, however regardless of the launch angle it will increase launch speed when holding up or decrease it when holding down. Holding the stick left or right has a LSI multiplier of 1 so they aren’t affected by it. Holding up will increase x1.095 launch speed while down will decrease it with a multiplier of x0.92, other angles will approach x1 the more horizontal the stick direction is.
Formulas:
Between 0° and 180°
1 + ((1.095 - 1) * sin(angle))
Between 180° and 360°
1 + ((1 - 0.92) * sin(angle))
In patch 1.0.4 (3DS) LSI had a change, previously it could be done with any attack but with this patch a limitation was implemented. Depending on the attack launch angle the move could be LSI-able or not. This was probably done to prevent the “holding down on 90° moves allow you to survive longer than DI’ing to the side” and limited LSI to be applied when not launched with an angle of 65°-115° and 245°-295° (exclusive range, you can LSI moves that launch you 65° but not 65.0001°)
So how the game considers the launch angle? Well normally you would think that it is move angle + DI angle change… but Sakurai decided to add something... as some may know gravity increases vertical launch speed so he decided to recalculate launch angle after adding gravity boost, making characters have variable launch angles depending on their gravity and KB.
On the last frame of hitlag the game does the following steps:
- Reads the stick direction
- Calculates DI angle change
- Calculates launch angle (move angle + DI)
- Calculates Launch Speed (KB * 0.03)
- Calculates and adds gravity boost to vertical launch speed (5 * (gravity – 0.075))
- Recalculates launch angle (atan2(vertical launch speed, horizontal launch speed))
- Checks if the move can be LSI’d
- Calculates LSI multiplier
- Applies multiplier to launch speed
After all this technical stuff, you could ask… And how this affects in-game? Well it makes DI more complex as most people know.
For example Charizard Uthrow, having an angle of 70° it cannot be LSI'd unless it is DI'd down and away, DI'ing down and away is the most optimal angle to avoid getting killed, plus because it is down it will have reduced launch speed making it better than other options.
So then which is the optimal DI angle? It depends on your situation.
For example with Roy's Fsmash in this situation down and in seems like the best angle to return to the stage, but left is better for not getting killed on the right blast zone, while down and away is the best one for avoiding vertical KO. The trick to get the best DI/LSI combination to avoid losing a stock is trying to get the best DI angle where you can hold the control stick down, if not try to go for left or right.
However this changes when we change survivability to avoid combos when you get tumble where holding up to increase launch speed can help you get out of range of the next move.
Well I think this should cover how LSI works and give you a general idea of how to use it for your advantage, thank you for reading.
I will still try to make the video covering this stuff someday but feel free to ask me anything if you have doubts regarding LSI on Twitter @Ruben_dal
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