Xorg and compositing

[Buffoon]

Hello forums

I cannot get compositing to work. This is not important, really, but I'm curious.
I never cared about eyecandy and my setup is very basic. Using no-multilib profile. I added USE flags as necessary when I installed Xorg, but there certainly are some flags turned off compared to desktop profile.
Since nowadays Chromium misbehaves without compositing manager I decided to install one. This is where the problem started. First I tried xcompmgr. This resulted in a chaotic desktop, all open windows disappeared and started flashing, appearing/disappearing randomly. No error message. No errors in logs. Then I tried picom, it runs and Chromium is happy with it. However, I thought since I have it then why not transparency. I am unable to get any effects working, may it be some component of Xorg is not playing along?

My Xorg log: https://dpaste.com/E9XPCLQL7

Where should I look to find out why xcompmgr goes berserk and picom does nothing?

[The Main Man]

I faced the same problem with no-multilib, problem is in the X use flag which that profile unsets globally, so you can set that flag globally and update the @world
At least I think that's the problem in your case, anyway you can find my recent question about that here :
https://forums.gentoo.org/viewtopic-t-1124551-postdays-0-postorder-asc-start-0.html

Yeah reading that now... with picom it was actually opengl use flag

[Buffoon]

Thanks for looking into this. I had opengl and X already enabled in package.use for most packages which have these, enabling both globally did not change anything, no package required rebuild. Here is my glxinfo, just in case: https://dpaste.com/3BHP6YPF3
I do not see any verbosity options for picom, it has debug mode, though. Not sure if that helps with my problem. Unfortunately X has never been my cup of tea ...

[The Main Man]

Well, don't know then what could be the problem.
I figured what was the problem in my case in the log file, I still have that error message when I look at the log file, it was this :

[Buffoon]

Thank you! Knowing this works for you like this is really helpful.

[The Main Man]

I said that because you didn't mention picom.log and is there something useful in it, in my case that info helped.
Also, the config posted was so that you can see how to enable the log file and more importantly transparency, in case you don't know (I don't know if you do)

Are you using the same config for picom that you used in desktop profile ?
If yes and transparency was working there and it doesn't now in no-multilib, then you're missing some of the use flags.

I'm sorry I can't help you directly on the first try and solve your problem right away, I tried to help ... good luck!

[Buffoon]

I didn't know picom can log! I tried to read the man page - which does not exist in my system and then I was looking at picom -h output, read Arch wiki, and some other places. None of them mentioned logging. Now I realize picom is not reading conf file, I put it in ~.config/picom.conf - which is supposed to be a valid location. I started picom with a bunch of command line options in attempt to enable transparency, and there was no transparency. BTW, I've never used desktop profile. This install was plain multilib once, I guess for Adobe flash perhaps which was 32-bit only back then, then I converted it to no-multilib many years ago.
Here is my mesa

[The Main Man]

Location of the config file is good, I believe your problem is in that config file.
The rest doesn't matter (USE flags etc.), picom is working in your case, but as far as I know transparency is working only if you specify for which windows you want transparency.
Like I did for my terminal only

[Buffoon]

I said it is not reading conf because there is no log. Meanwhile I found this: https://github.com/ibhagwan/picom/blob/next/picom.sample.conf

Edit: After changing the logfile path to absolute there is log. Now I'm getting somewhere ...