Assassin's Creed Brotherhood shadows flickering issue

[CTRL-ALT-DEL-92]

Dear G9 Devs,

I'm currently running ACB via G9 with outstanding performances (my gpu is AMD Ellesmere [Radeon RX 470/480/570/570X/580/580X/590] vendor: Sapphire Nitro+), the only hideous issue is with some very eyes hurting shadows flickering on the protagonist cape and costume. The solution I found to circumvent this problem was changing the protagonist outfit to a totally black version of his costume, with the white one the flickering is almost eyes damaging.

I've successfully made an apitrace to help you find a fix.
https://drive.google.com/file/d/1WdU6N_qyIQ4yTkvuOfAKh8nfluBIVekk/view?usp=sharing

Thanks in advance for your help

[axeldavy]

Tried the trace and could reproduce. This looks like some rounding issues, possibly related to the depth buffer.
If you play with graphic settings in the game (with and without antialiasing, etc) is there any impact on the issue ?

Thanks

[dungeon007]

And i cant reproduce this on CIK APU... so this sounds like hw specific, maybe Polaris issue.
So play with AMD_DEBUG flags, maybe it is nodcc or something of that sort... wild random guess because CIK do not have DCC.

[CTRL-ALT-DEL-92]

Dear G9 Devs,

Thanks for the usual and fast support, I've changed the in game settings as suggested by axeldavy with no avail no graphic option has an impact on the issue, just changing costume's colour palette to total black seems to be an in game fix for the problem. I could not try the AMD debug solution (suggested by dungeon007) because I don't know how to activate it, I need a little how to guide.

[CTRL-ALT-DEL-92]

I've finally enabled the AMD_DEBUG=nodcc flag but with no avail... The game isn't affected, just changing the character costume colour affects the problem.

[dungeon007]

Bug is fine, but probably not actually hw specific... it looks like REGRESSION bug since last year commit 55d81214c9d800c0667337808a82143ebab17c1a

radeonsi: replace gl_FrontFacing with a constant if one side is always culled

[CTRL-ALT-DEL-92]

Bug is fine, but probably not actually hw specific... it looks like REGRESSION bug since last year commit 55d81214c9d800c0667337808a82143ebab17c1a

radeonsi: replace gl_FrontFacing with a constant if one side is always culled

Should the mesa developers be informed of this?

[dungeon007]

Yeah, i already opened a bug there https://gitlab.freedesktop.org/mesa/mesa/-/issues/11484