Thread by @LealFireball

**SSB ULTIMATE BUG REPORT**

It’s an important bug with Stage Collision Detection that heavily affects everything that encompasses transitioning into/from an air state, affecting game feel and intuitiveness of movement too, chain of tweets has the details, click thread to read

#SmashBros has been heavily modifying the basic Melee engine since Brawl to make the game play in new ways, but among those modifications, some bugs were introduced. One of them pertains to how the game detects collision between characters and stages, like landing during actions

All of these games use the same system for that purpose, it's called "Stage Collision Detection", but since Brawl’s release it is not working properly, in this tweet chain I'll visually explain how that works

The ECB uses the position of a few bones to effectively tell the position of the character on screen, this means that their position is highly dependent on their poses during an animation. It's intuitive and effective for the players

Along with the ECB, each character has an origin point, that is the char’s “true” position, it uses the first bone in the hierarchy (TopN for Melee and Brawl, TransN for Smash 4), this work in tandem with the ECB to position the character where it need to be

As you can see in the example, Sheik is able to do a “No-Impact Landing” on the platform because her ECB is over it, she is also visually over. Even though her origin point is not she is able to land thanks to this clever system

The game uses the ECB points to tell the game to let Sheik land on the platform, moving her origin point instantly with her. This disparity happens because in air animations, characters are usually farther from the origin point, unlike ground animations

In this example for Smash 4 ZSS lands early, even though she's visually far away from the ground. This happens because the game is not considering the Environmental Collision Box (ECB) despite the game presumably having system available in perfect working condition

The reason I believe this bug persists in Smash Ultimate is that we can see a very similar example in ZSS's character trailer, as well as all around gameplay videos if you know to look for it

Smash 4 has a lot other very glaring examples, in this one ZSS warped very severely to the ground during an Up Air, that's why it's hard to hit people on the ground with it

One of the most emblematic examples in Smash 4 of this not working is the Ryu struggle. Ryu completely goes over the lower Dream Land platform, but is unable to land on it, that is because his ECB is over the platform but his origin point is not

Here’s an image of his Jump animation, see how the origin point is way lower? It’s dictated by the small, red colored square, that's the TransN Bone

On the third, and last chain of examples, you probably ran into this if you played Ike

The same obviously happens in Smash 4

And here's how it goes when SCD is working properly #ShoutoutstoMagus

I forgot to change the text saying "TopN Bone" to "TransN Bone" in this particular gif, sometimes it's hard to remember that they changed it with smash 4