Bug / Crash 2 Rendering bugs on iOS(Metal)

[cliv3dev]

Hi,



I am reporting 2 rendering bugs for Obi Fluid on iOS.



Unity 2022.3.60

URP or SRP

iOS v18.3.2

iOS SDK: 18.2

Obi Fluid [7.0.5]

Solver backend: Compute (GPU) and Burst(CPU)

Test scene: FluidViscosity



When running on iOS, 

1. test scene with Burst backend, there is a black color issue in the transparent fluid rendering (same bug in SRP or URP), see screenshot 20250314_135736000_iOS.png


2. test scene with Compute backend, fluid rendering starts with the same look as Burst and with same black color bug but after 2 or 3 seconds, the fluid mesh explodes, see screenshot 20250314_140447000_iOS.png



I built on PC (DX11) and Meta Quest (Vulkan), and the rendering presents no bug at all : com.oculus.vrshell-20250314-153625.jpg



So, seems to be an issue with Metal API...

Hope this helps !

[josemendez]

Hi there!

Thanks for taking the time to report this! I'm unable to reproduce this on an Phone Xs, iOS 17.6 using Obi 7.0.5 / Unity 2021.3.4f1. We usually develop on Mac using Metal then test in all other supported platforms, so it doesn't seem to be a Metal-specific issue (I'm not 100% sure there's any differences in the API that would affect mobile vs desktop, so there's still a chance Metal is the culprit).

Just to get it as close to your specs as possible, which iOS device are you trying this on? Will try to get my hands on something as close to what you're using as possible and get back to you.

kind regards,

[cliv3dev]

Hi there!

Thanks for taking the time to report this! I'm unable to reproduce this on an Phone Xs, iOS 17.6 using Obi 7.0.5 / Unity 2021.3.4f1. We usually develop on Mac using Metal then test in all other supported platforms, so it doesn't seem to be a Metal-specific issue (I'm not 100% sure there's any differences in the API that would affect mobile vs desktop, so there's still a chance Metal is the culprit).

Just to get it as close to your specs as possible, which iOS device are you trying this on? Will try to get my hands on something as close to what you're using as possible and get back to you.

kind regards,

Hola Jose,

it's an iphone SE 2nd gen so nothing fancy.
Just the OS and SDK version which are the latest versions and XCode is v16.2
You can find enclosed the log when executing from XCode...
After some frames without issues, Metal is not happy:
Metal: Blending not supported for format 125
Type: Notice | Timestamp: 2025-03-17 14:25:01.935662+01:00 | Process: obi-ios-test | Library: UnityFramework | TID: 0x14a3e5
Metal: Blending not supported for format 125
-> applicationDidBecomeActive()
Type: stdio
Execution of the command buffer was aborted due to an error during execution. Caused GPU Address Fault Error (0000000b:kIOGPUCommandBufferCallbackErrorPageFault)
Type: Error | Timestamp: 2025-03-17 14:25:04.431445+01:00 | Process: obi-ios-test | Library: Metal | TID: 0x14a3b9
Execution of the command buffer was aborted due to an error during execution. Caused GPU Address Fault Error (0000000b:kIOGPUCommandBufferCallbackErrorPageFault)
Type: Error | Timestamp: 2025-03-17 14:25:04.461791+01:00 | Process: obi-ios-test | Library: Metal | TID: 0x14a3b9
Execution of the command buffer was aborted due to an error during execution. Ignored (for causing prior/excessive GPU errors) (00000004:kIOGPUCommandBufferCallbackErrorSubmissionsIgnored)
Type: Error | Timestamp: 2025-03-17 14:25:04.461982+01:00 | Process: obi-ios-test | Library: Metal | TID: 0x14a3b9
...