Dmabuf based render buffers!?

Hi!

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?

Cheers
Fred