Hello Francesco,
Francesco Tamagni wrote:
> hi to all.
> i heavily use fake FBOs ( setFBOOn( false ) ).
>
> the problem is that i expect that fake FBOs, as they inherit from
> Viewport, behaves like Viewports when i resize them ( setSize() ).
> Instead, i discovered that FBOs do this:
>
> Window *win = action->getWindow();
>
> // Let the window handle resizes, to avoid interfering with the
> // FBOViewports settings
>
> win->resizeGL();
>
> before each render. this basically does glViewport() using full window
> size... but if i did setSize to render on a sub-portion of screen, it is
> ignored and the content are rendered on the full window.
have you tried using the SFStorageHeight SFStorageWidth fields ? AFAIUI
this can be used to set the size of the texture that is created and if
the window is larger than that texture it was my understanding that the
FBOViewport only renders to a part of the window.
> there are two possible solutions to this problem:
>
> 1 - don't use fake fbo, use true ones.
> 2 - let setFBOOn(false) interfere with FBOViewports settings
>
> + solution 1 has the drawback that i have to replicate a lot of code to
> support video cards on which FBOs don't work, using big IFs
ideally, the only difference between real and faked FBOs should be the
performance...
> + solution 2 has the drawback that it is not semantically consistent
> with FBOs (that doesn't support offsets), but is semantically consistent
> with the Viewport concept, from which OpenSG derives FBOs...
hm, I don't quite understand what you are referring to with offsets
above. The fact that FBOViewport draws into framebuffer 0 (i.e. the
window) when emulating FBOs is just because in that case it's the only
available framebuffer ;)
Regards,
Carsten
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