Mobile A glitch with going down out of portals

[Green_Metaknight]

Your Terraria Device

iPad (9th generation)

Mobile OS

iPadOS 18.1

I was recently doing some experiments with an Omnidirectional Railgun, when I discovered that if you try to go down using it, your vertical momentum resets and works as if you're holding a portal gun. i.e; you stop falling, and then accelerate (At the same acceleration speed that one accelerates with when falling while holding a portal gun) to the fall speed that is normally only achieved with a portal gun. I'm not sure the exact conditions of this glitch, but I think it might be caused by either the very high speeds, or a teleporter trying to teleport the player at the same time as the player using the portal. Speaking of which, I'm not sure if this is related, but when I preformed this glitch, I didn't come out of the exit portal, I came out of 6 blocks below the portal; the same distance that I was teleporting with the teleporters in the railgun.
I couldn't attach a video because the one I took is too big (I converted it to a gif btw), but here's a screenshot:

When going diagonally out of the omnidirectional railgun, the same glitch applies to the vertical position and vertical movement, but horizontal speed is unaffected.

 

[Dapling]

I’m guessing the game tried to retain your speed and also reset it in the same frame, which caused you to take the correct speed for 1 frame and then reset it immediately after.
My theory is that your hitbox momentarily skipped past the portal due to your speed and then the game corrected it which caused some jank. I don’t think this could feasibly be patched just because it’s consistent with how the game’s failsafes work (the same failsafes which prevent you from teleporting through walls at high enough velocities)

Of course, my experience with the game’s code is limited, so that’s just a guess

 

[Green_Metaknight]

I’m guessing the game tried to retain your speed and also reset it in the same frame, which caused you to take the correct speed for 1 frame and then reset it immediately after.
My theory is that your hitbox momentarily skipped past the portal due to your speed and then the game corrected it which caused some jank. I don’t think this could feasibly be patched just because it’s consistent with how the game’s failsafes work (the same failsafes which prevent you from teleporting through walls at high enough velocities)

Of course, my experience with the game’s code is limited, so that’s just a guess

That sounds feasible, but I've used this same railgun to launch myself horizontlally, and the portals didn't glitch my movement at all.
Also, it actually is possible to teleport through walls with a high enough velocity; the failsafes just stop you from clipping into the wall by moving into the same tile as it.

 

[Green_Metaknight]

Here's a picture of me trying to go diagonally down (The exit portal is on the right side of the image, partially obscured by the cell phone info):

Also, I think I just realized how this glitch might work.
When I go through the portal, I partially clip into the ceiling above said portal, while also activating the teleporter.
The downwards momentum is canceled by the partial ceiling clip that happened at the beginning of the tick, but while the portal portals me, my stopwatch glitches into thinking that I still have about 500 mph vertical momentum.
The portal converts the downwards teleporter movement into downwards teleporter movement (Or diagonal downwards teleporter movement), and the teleporter movement resolves itself, sending me to a position 6 blocks away from the exit portal in the direction that the exit portal is facing.
Then when calculating gravity, the game thinks that since I just came out of a portal, I must be holding a Portal Gun.
So I fall for the next few seconds until I hit the ground, my stopwatch subtracting my downwards momentum from the vertical momentum it thinks I still have to come up with a new number, the stopwatch number eventually capping out at about (500 minus the top falling speed from portal gun), and my actual fall speed capping at the portal gun fall speed, and then both speeds resetting to zero once I hit the ground and the stopwatch realizes I'm not moving anymore.

So if I'm correct in this theory, there are 4 glitches that are contributing to this glitch:
The stopwatch's inaccurate measurement of my speed,
The teleporter and portal causing the player to exit from beyond the exit portal when they're both activated in the same tick (I don't want this to be patched, it's cool),
The fact that the partial ceiling clip reset my vertical momentum despite me teleporting through a portal after the partial clip in the same tick,
And the gravity glitching and thinking I was holding a portal gun.

 

[Nescre]

Thanks for the report - would you be able to send me your world file so I can compare this behaviour against PC?

 

[Green_Metaknight]

The Omnidirectional Railgun is to the left of spawn and slightly up btw, on the other side of the giant tower.
Here's the world file: