| Re: [hatari-devel] Suggested patch to fix the SDL GUI on KMS/DRM |
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- To: hatari-devel@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [hatari-devel] Suggested patch to fix the SDL GUI on KMS/DRM
- From: Thomas Huth <th.huth@xxxxxxxxx>
- Date: Sat, 31 Oct 2020 08:55:12 +0100
- Dkim-signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.de; s=2017; t=1604130914; bh=4VRYaymrAKJJib4E96gihxjOBKUuJtBqi1HxvBlmemQ=; h=Date:From:To:Subject:From; b=KzuW0TEtBs/IKMKNRRyYXVZ2AHeNmqVCYu3tj0MISqEgSaTChkdUl5niVY6434G7w q16jv/M16+POLZDAvCmFodB6gtc3R2qjMDYplsLY3IGntXskzW7j+ZCkChbTOeiafp q9uzBSlo3apubDF1anaAgWVzyuMGzNLS2ZS25/LknaYIrvORzoSMOGTZTAYeOESQoY zIQ6CsDYEp74DC3ykvSp5LOugHh8JLaqwiT4Y9jMo4xIECaMBEhe1HsduIa4vVIqTm Doi0TnNm5vRQHF5GXibZ4ufiwUeMW4St4OTBQcHMfQj1aFvEtsHyUFmcLLyCUl5wAG 2OTdY9onAk2Sw==
Am Sat, 31 Oct 2020 08:49:39 +0100
schrieb Thomas Huth <th.huth@xxxxxxxxx>:
> Am Sat, 31 Oct 2020 07:55:28 +0100
> schrieb Jens Guenther <dbotw@xxxxxxx>:
>
> > Hi,
> >
> > while discussing an issue with the Tandy TRS-80 emulator SDL2TRS in
> > the RetroPie-Forum (1) regarding KMS/DRM with SDL2 on the Raspberry
> > Pi 4 and Wayland, it turns out that the patch also fixes it for
> > Hatari ...
>
> Interesting ... we removed that call three years ago, after deciding
> that it is not necessary, see:
>
> https://git.tuxfamily.org/hatari/hatari.git/commit/?id=5a59019da3e
>
> and the related discussion:
>
> https://listengine.tuxfamily.org/lists.tuxfamily.org/hatari-devel/2017/02/msg00144.html
>
> Why is the call necessary with KMS/DRM and Wayland? Does it have any
> side effects there beside clearing the surface?
>
> So in case we have to include this again, do we have to do it on each
> frame? Or would it be ok to only call it e.g. only on every 50th frame
> to avoid the speed penality of the unnecessary screen clear?
Ok, I've found some more information here:
https://wiki.libsdl.org/SDL_RenderPresent
Citing: "You are strongly encouraged to call SDL_RenderClear() to
initialize the backbuffer before starting each new frame's drawing,
even if you plan to overwrite every pixel."
.... so I assume we should simply add the SDL_RenderClear() again, to be
on the safe side? Nicolas, what do you think?
Thomas