D25904: [libkwineffects] Set original backend framebuffer for render targets

fredrik added inline comments.

INLINE COMMENTS

> romangg wrote in kwinglutils.cpp:1091
> Can you explain some more? So whenever we change the current viewport call "setDefaultViewport"?

No, the idea is that whoever calls setKWinFramebuffer() would also call setDefaultViewport() to define the viewport that should be used when that framebuffer is bound.

Right now pushRenderTarget() queries GL_VIEWPORT so popRenderTarget() can restore it when the last custom render target is popped. But if we already know what the viewport should be, we don't have to query it from the GL.

> romangg wrote in kwinglutils.h:552
> I find naming this API something like defaultFramebuffer difficult (as outlined in D25904#575910 <https://phabricator.kde.org/D25904#575910>): because the default framebuffer is not changed when the function is called. The default framebuffer is what this can be changed to but it is not always the default framebuffer. Would `setBackendFramebuffer` be alright with you? Or `setBottomFramebuffer`?
> 
> I agree the documentation is misleading. I will change it up a bit.

For some reason phabricator didn't warn me that the revision had been updated, so I didn't see that Vlad had  already suggested that.

Between those two I think I would prefer setBottomFramebuffer(). But how about setSurfaceFramebuffer()?

REPOSITORY
  R108 KWin

REVISION DETAIL
  https://phabricator.kde.org/D25904

To: romangg, #kwin
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