iOS Mobile Renderer Black Screen

[TCROC]

Tested versions

• Reproduceable In: 4.4.dev.mono.custom_build.f0e971730

System information

Godot v4.4.dev.mono (f0e9717) - macOS 15.0.1 - Multi-window, 1 monitor - Metal (Forward+) - integrated Apple M2 (Apple8) - Apple M2 (8 threads)

Issue description

When exporting to iOS set to use the mobile renderer, it renders with a black screen:

When exporting to iOS set to use the Forward+ renderer, it renders just fine:

Here are the respective logs:

Note

The Forward+ Renderer Log has many errors, but that is the one that actually renders correctly. The Mobile Renderer log only has 1 error, but renders with a black screen.

Mobile Renderer Log

Godot Engine v4.4.dev.mono.custom_build.f0e971730 (2024-11-16 22:16:24 UTC) - https://godotengine.org
Metal 3.1 - Forward Mobile - Using Device #0: Apple - Apple A12 GPU (Apple5)

ERROR: Mouse is not supported by this display server.
at: mouse_get_position (servers/display_server.cpp:508)

Forward+ Renderer Log

forward_plus_log.txt

Steps to reproduce

1. Use Godot with double precision and mono support.
   • I'm not certain if this is necessary as I haven't tested other builds, but that is what I am currently using.
2. Open the MRP
3. Export to iOS
4. Install to an iPhone
5. See that a black screen renders
6. Change project settings mobile rendering method to Forward+
7. Export to IOS
8. Install to an iPhone
9. See that cube renders

Minimal reproduction project (MRP)

mrp.zip

Edit:

Here's the table of tested snapshots:

✅ = vulkan mobile works as expected
❌ = vulkan mobile blank screen

Version	Status
4.3.stable	✅
4.4-dev1	❌
4.4-dev2	?
4.4-dev3	?
4.4-dev4	?
4.4-dev5	❌

[Calinou]

Can you reproduce this on 4.3.stable?

[TCROC]

I will go check

[TCROC]

I initially tried to test in 4.3 by building from source but was unable to because my Mac OS received an LLVM update. And this version of LLVM can no longer compile code prior to that fix we put in a while back where LLVM rolled out some breaking changes. But I do have good news! I was able to reproduce the issue with dev snapshots and confirm that things work as expected in 4.3-stable. So this is indeed a regression. I'm going to start bisecting, but there is the table of what I have tested so far:

✅ = vulkan mobile works as expected
❌ = vulkan mobile blank screen
? = untested

Version	Status
4.3.stable	✅
4.4-dev1	?
4.4-dev2	?
4.4-dev3	?
4.4-dev4	?
4.4-dev5	❌

[TCROC]

Also note that I reproduced this with normal Godot. It occurred in the 4.4-dev5 snapshot without mono support. And I believe those snapshots do not have double precision either right? Which would lead me to believe this issue is not related to mono support or double precision.

[TCROC]

Version	Status
4.3.stable	✅
4.4-dev1	❌
4.4-dev2	?
4.4-dev3	?
4.4-dev4	?
4.4-dev5	❌

So it was first introduced somewhere between 4.3.stable and 4.4-dev1.

@Calinou I found where it was introduced in regards to snapshots :).

[bruvzg]

Metal 3.1 - Forward Mobile - Using Device #0: Apple - Apple A12 GPU (Apple5)

Default backend for Mobile/Forward+ on macOS and iOS was changed to new Metal renderer. While Vulkan renderer should support A12 (it is the oldest SOC it should run on), I'm not sure what's the minimum requirement for Metal renderer. Try setting rendering/rendering_device/driver.ios in the project settings to vulkan.