Re: [hatari-devel] Suggested patch to fix the SDL GUI on KMS/DRM

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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:
> and the related discussion:
> 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:

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?


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