Decals get distorted on certain MeshParts

[mrfergie]

Expected Behavior

In my game, we have police cars (made of MeshParts) with decals on them. This is how they should look:

Screenshots

Description of Bug

Some users report that on certain devices, the decals on certain cars are get getting distorted. It looks like the rear half of the decal gets erased and put over the front half. The decal changes as you move your camera around. It’s a 100% frequency on certain devices. Reports started coming in around March 18th.

Screenshots and Video

GIF: https://gyazo.com/c08bc02dddd6668254e4a8c0150aa259

The screenshot below shows the entire decal missing. The user said he’s on a MacBook and it’s not a loading issue. This report came on the same day the iPad reports started. It doesn’t look the same, but I’m not sure if its related to the same bug.

Frequency & Repro

This only happens on certain devices. It’s mostly reported on newer model iPads and iPad Pros. There have been a couple similar reports on MacBook. I’ve seen no reports on PC. I am only able to repro it on my iPad Pro 4th gen, and not on my 5th gen iPad.

List of devices users reported getting the bug on (may not be the complete list):
2020/4th Gen iPad Air
2020/4th Gen iPad Pro 11 in.
2020/8th Gen iPad
2018/3rd Gen iPad Pro 12.9 in.
MacBook (unconfirmed)

Game link: Emergency Response: Liberty County - Roblox
(this happens in multiple games tested with the same models)

Note: I can send the car mesh model on which this problem occurs in DMs.

Here is a similar bug report, but it’s closed and is only a Studio bug. Ours is happening in game, on certain tablets.
https://devforum.roblox.com/t/in-game-studio-image-corruption-textures-and-decals/985094

[Discgolftaco231 (w_av)]

Yeahhh… This is a problem

So (don’t quote me haha) I think because Apple (and mobile) devices use a different rendering engine, the renderer does not know how to properly warp the decals around the mesh.

I honestly dont think there is a way to get around this.

You might be able put the decal on an invisible part if the player is on mobile, but I have played your game (nice job, by the way), and I know that that would take a while to set up because all of the cars are different.

[mrfergie]

I’m sure it’s fixable. This is only a recent bug - they worked before this month just fine.

@mrfergie

Reports started coming in around March 18th.

[Discgolftaco231 (w_av)]

Okay.

Maybe this has to do with the AO and lighting fixes they did a month ago? There were performance fixes that they did to mobile at the same time of the AO update. Sooner or later, someone over at HQ will realize this (hopefully)

EDIT: I am also experiencing this bug on 3rd Gen iPad Pro

[ProvenData (John)]

Hi there mrferige, so as you know I had this same bug. Now when this happened I was contacted by a Roblox engineer called @fnublox. He said contact him if this bug is re-occuring so I’ve taken the liberty to add you to the DMs with him and I. (No pun intended.)

Also I’m currently not experiencing this bug using Mac 10.14.6 and Studio 0.472.5.419960 . However I did notice this would go away sometimes and re-appear and also be on a case by case basis.

[MiroSpectre (Miro)]

@fnublox will be able to help you out with that. I’ve had that issue prior as well but I work off a macbook.

[mrfergie]

For anyone else having this issue, here’s what a staff member told me regarding this issue. Marking as solved since they said it’s not a Roblox bug but an Apple bug.