Teared rendering results with artifacts when blend mode is translucent

[hannojg]

Describe the bug

When rendering content with filament with transparency the image is pixelated / is torn apart / has artifacts.
In general it works, we were able to reproduce this especially on google pixel devices.
The original discussion started here:

• Pixelated rendering results on android devices #7729

To Reproduce

1. Run the sample-transparent-view demo on a google pixel device. We used a Pixel 7 Pro

Expected behavior

its rendered without tearing and artifacts.

Screenshots

IMG_7750.MOV

IMG_7749.MOV

Logs
If applicable, copy full logs from your console here. Please do not
use screenshots of logs, copy them as text, use gist or attach an uncompressed file.

Providing those in a moment, will run the sample app with the debug flags enabled.

Desktop (please complete the following information):

• OS: Android
• GPU: Mali-G710 MP7
• Backend: OpenGL

Smartphone (please complete the following information):

• Device: Pixel 7 Pro
• OS: Android 14.0

Additional context

The problem seems to be fixed on Pixel devices when either:

• turning off post processing effects altogether using view->setPostProcessignEnabled(false) (note: disabling each post processing effect doesn't fix the issue, only turning it off completely)
• using Vulkan as backend

[hannojg]

Note: not sure if its strictly the fact that its using transparency or the fact that no skybox is used.
In our app I tried to set blending mode to opaque and set no clear options, and this still happened.

The other samples work, but they all use skyboxes if I am not mistaken

[hannojg]

Update:

In the multi-view example I was able to circumnavigate the issue by commenting out this line:

filament/android/samples/sample-multi-view/src/main/java/com/google/android/filament/multiview/MainActivity.kt

Line 136 in 99eac62

view4.blendMode = View.BlendMode.TRANSLUCENT;

So I assume it's not related to the skybox but really just to the translucent blending mode.
(In our app I need to render the content with transparency, so just turning it off is not an option for me unfortunately)

[pixelflinger]

I can reproduce, the problem seems to be linked to our use of the framebuffer_fetch extension on these devices. Enabling any feature that turns that off will appear to fix the problem. For instance enabling MSAA, TAA, DoF or bloom. Also disabling post-processing or color grading. This needs more investigation...

[pixelflinger]

The problem also goes away when I change our internal format from RGBA16F to RGBA8. This starts looking like a driver bug.