[Mesa-dev] Dmabuf based render buffers!?

[Blueroom]

Hi and thanks for your replies!

Note though that I want to get hold of the image/pixels after they have
been processed by shader(s).
So not the raw texture being fed in.

So maybe it would be the contents of a FBO or similar.

Cheers
Fred

On Fri, Jan 15, 2021 at 3:59 AM Christian König <
ckoenig.leichtzumerken at gmail.com> wrote:

> Am 15.01.21 um 11:26 schrieb Michel Dänzer:
> > On 2021-01-14 8:02 p.m., Blueroom wrote:
> >>
> >> Hi Everyone!
> >>
> >> I have a program that’s using dmabuf’s to create a zero copy
> >> camera->GL texture pipeline and it’s working great on my RPi4.
> >>
> >> Now as a last step I want to access the pixels that Iv’e processed in
> >> gl with shaders, on the cpu.
> >>
> >> Iv’e been told that on the Raspberry Pi OpenGL is sharing the same
> >> memory as the cpu so I’m hoping it would be possible to do something
> >> like a dmabuf on the ‘way out’ too?
> >>
> >> Does anyone have any pointers in how this could work?
> >
> > I'd recommend using glGetTexImage or other similar GL APIs for getting
> > the data out of the GL texture.
> >
> > While mmap of a dma-buf file descriptor works in theory, direct CPU
> > reads from GPU accessible memory can be very slow on some platforms.
> >
>
> Yeah, agree. Additional to that you don't know the format of the DMA-buf
> of the texture.
>
> The input image is most likely linear, but the output might be tiled.
>
> Christian.
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/mesa-dev/attachments/20210115/aa0323c3/attachment.htm>