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.
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