[SDL] SDL_PollEvent() with an offscreen render target

Andreas Falkenhahn andreas at falkenhahn.com
Tue Sep 9 09:27:23 PDT 2014


Done:
https://bugzilla.libsdl.org/show_bug.cgi?id=2725 

On 20.08.2014 at 07:10 Sam Lantinga wrote:

> Can you report it as a bug in bugzilla so it doesn't get lost in e-mail?


> Thanks!


> On Mon, Aug 18, 2014 at 1:47 PM, Andreas Falkenhahn <andreas at falkenhahn.com> wrote:
>  
> Thanks. Have you seen my other mail titled "Refresh trouble with SDL_WINDOWEVENT_EXPOSED"?
>  This could also be a bug. And there's also a very short test case attached ;)
>  

>  On 17.08.2014 at 23:35 Sam Lantinga wrote:
>  
 >> This is fixed, thanks!
 >> https://hg.libsdl.org/SDL/rev/a8cbb653aea4
>  
>  
>  
 >> On Fri, Aug 15, 2014 at 6:39 AM, Andreas Falkenhahn <andreas at falkenhahn.com> wrote:

 >> Hi,

 >>  is SDL_PollEvent() only supposed to be used with the window being the current
 >>  render target?

 >>  I've noticed that in case an offscreen texture is the current render target
 >>  SDL_PollEvent() can do quite some strange things to the renderer. For example,
 >>  if the user resizes the window while an offscreen texture is the current
 >>  render target, the window's viewport dimensions will *not* be adapted automatically.
 >>  Instead, SDL probably adapts some parameters concerning the offscreen rendering
 >>  to the texture but IMHO it doesn't really make sense to take updated window
 >>  dimensions and apply them to the offscreen texture... they should be applied to
 >>  the window instead.

 >>  This behaviour can cause quite some confusion because in that case you'd have
 >>  to call SDL_RenderSetViewport() manually although this is normally done automatically
 >>  by the event handler on window resize.

 >>  I am attaching a small demo program which shows the issue. You can see that
 >>  the viewport coordinates aren't adapted correctly in case SDL_PollEvent() is
 >>  called while an offscreen texture is selected as the render target (SDL_RenderCopy
 >>  in line 101 is supposed to scale the offscreen texture to the window dimensions
 >>  but it doesn't do it because the viewport coordinates haven't been updated.)

 >>  If SDL_PollEvent() can't deal with render targets other than the window I
 >>  think this should be mentioned both in the docs of SDL_PollEvent() and SDL_SetRenderTarget().

 >>  --
 >>  Best regards,
 >>   Andreas Falkenhahn                          mailto:andreas at falkenhahn.com
 >> _______________________________________________
 >>  SDL mailing list
 >>  SDL at lists.libsdl.org
 >>  http://lists.libsdl.org/listinfo.cgi/sdl-libsdl.org

>  
>  
>  
>  
>  --
>  Best regards,
>   Andreas Falkenhahn                            mailto:andreas at falkenhahn.com
>  
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>  



-- 
Best regards,
 Andreas Falkenhahn                            mailto:andreas at falkenhahn.com



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