Low client FPS causes irregular and inconsistent character collisions

Issue Type: Other
Impact: High
Frequency: Often
Date First Experienced: 2021-04-04 00:04:00 (-04:00)
Date Last Experienced: 2021-04-24 00:04:00 (-04:00)

Reproduction Steps:

  1. Have a low FPS device or use an FPS unlocker to simulate low FPS
  2. Observe that character collisions are incredibly inconsistent

Repro Place: LowFPSCollisionRepro.rbxl (25.5 KB)

Expected Behavior:
Low FPS players should have normal collisions. If not, make it well-known that low FPS players will have these strange interactions.

Actual Behavior:
Low FPS players have abnormal collisions. Some can be used for exploiting, others are inconsistent - they can cause annoying reproduction confusion and may require major level design alterations to resolve them.

Partially phasing through parts


Low gravity used to show the collisions in slow motion

  • Players can sink through floors for several frames, often causing undesired deaths in obbies.
  • Legs can hit a death block that is anywhere from 0-5 studs below the safe ground!!!

Fully going through parts

https://devforum.roblox.com/t/noclipping-through-walls-with-roblox-recorder/23810
Players can purposely (or unintentionally) use low FPS to walk through walls.

Negating gravity

https://devforum.roblox.com/t/client-character-freezes-when-holding-right-click-on-top-of-window-repro/18876
Players can abuse low FPS via the nature of the client to completely negate gravity indefinitely.

Spawning under SpawnLocations

image
Players can even spawn under/inside of a SpawnLocation as a result! (I don’t have a screenshot of this, but I have indeed witnessed it)

Workaround:
It is possible to circumvent these odd interactions by completely redesigning parts of a game, but doing so is somewhat ridiculous. Low FPS should not cause these strange collisions.

4 Likes

No they aren’t, it was stated the exact opposite.

The point of mentioning using an FPS unlocker is to make reproduction easier. Not everyone has a phone that’ll average 5, 15, 20, etc. FPS.

Using an FPS unlocker to get an unfair advantage may be against the rules, I don’t know. I don’t use one to do this. Your point is completely unrelated to the topic at hand.

1 Like

Well using an FPS unlocker causes a lot of complication’s, the renderer of the server only goes up to 60 FPS, thus increasing your walk speed slightly faster with higher FPS, making game’s seem like you are speed hacking, another thing is you experience a lot of weird issues like what @cloakedyoshi has stated about lower FPS, which has been like that since the early days of Roblox with lag, and collisioning. 3rd higher the FPS, the more mechanical failure’s your likely to have in a Roblox game with the renderer only being able to handle at 60 FPS, knowing what affects it could cause for any other game.

1 Like

Yeah, just like how low FPS replicates the issue from OP’s post, unlocked FPS is a polar opposite.

The only thing I can get from this is the usual hint to never use an automatic banning system for cheaters, because of false positives.

Actually after viewing the RDC 2019 clip, it actually isn’t against the rules, I guess I just heard it wrong, my bad.

2 Likes

Thanks for the report! We’ve filed a ticket to our internal database and we’ll follow up when we have an update for you.

4 Likes

Recently saw this video on YouTube which highlights some of the problems with better visual clarity:

As you can see, the low FPS players sometimes temporarily or permanently clip through structures - causing undesired collisions as a result.

4 Likes