[BUG] - Broken png image sequence export

[samytichadou]

When rendering image sequence as png (with alpha in this situation), regularly some images from the sequence are randomly broken.
To fix this, i have to rerender several times to replace broken ones by clean ones.
I can't figure out the origin of this bug...

Here is a short video showing the issue

broken_png.mp4

Using friction rc2 and dev snapshot (Friction-1.0.0-CI-9a7a0271-x86_64) with linux kde neon wayland.

[rodlie]

Probably related to GPU, try using CPU and see if that fixes it.

Go to preferences and hardware, slide acceleration to the left (CPU) and disable path acceleration.

If you use some of the integrated effects (blur etc) you might want to consider setting them to CPU also. You can do that in the settings or on the effect.

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friction-blur-cpu-gpu-2025-12-01_15.53.33.mp4

[samytichadou]

thanks for the quick reply !
i'll try a bunch of renders to see if it works, is it something fixable for 1.0 ?
if not maybe keeping default pref to CPU would be preferable ?
I'm not familiar with the loss of performance, but even slower, i prefer to be sure of my render :)

[rodlie]

The performance penalty should be minor (if at all).

Some notes on GPUs:

• Some effects (blur etc) on some GPUs can introduce artifacts, switching the effect to CPU should fix it
• On some NVIDIA cards you may get flickering when using opacity in a scene, setting to prefer CPU in preference should fix it
• Some Apple/AMD/NVIDIA GPUs can have missing antialias, set MAA to x16

My plan was to have an option in the renderer to force CPU regardless of settings.

[samytichadou]

My plan was to have an option in the renderer to force CPU regardless of settings.

All right, seems to be a good way to prevent this at render time by leaving it untouched in the settings !

Still have concerns though, this means this could happens by default to a new user.
Why not using this forced CPU option or CPU settings by default, prompting on first launch that a GPU experimental is available but could cause glitches ?

Anyway thanks for the infos about GPU, i may have some issues with AA :)

Knowing this, should we let this issue opened as long as this "bug" persists ?

[rodlie]

Knowing this, should we let this issue opened as long as this "bug" persists ?

Yes, let's keep this issue open.

We could change the default. I will need to do some tests on various GPUs etc.