[Mesa-dev] Dmabuf based render buffers!?
fred.sund at googlemail.com
Fri Jan 15 18:31:40 UTC 2021
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.
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.
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