Compositors need to drive multiple connectors, each with its own vblank timings.
For each device, there's one separate rendering loop per output.
It's not possible to call liftoff_device_apply each time we want to submit a new
frame to one output, because this could touch another's output state, submitting
a new frame there in the process. When the other output will submit a new frame,
it'll get EBUSY (can't submit two frames without waiting for vblank).
Closes: https://github.com/emersion/libliftoff/issues/21
Add a fallback case for finding an eligible CRTC for the
selected connector. The encoder picked may not have been
wired up to that connector by the previous DRM master.
This example demonstrates how incremental layer updates should be applied. It
contains a basic rendering loop. Each layers has a back-buffer and a
front-buffer. The color of one of the layers will change at each frame.
Create a special layer that we will use only for composition.
If we manage to put all other layers into planes, we don't need to use it.
Otherwise, blend other layers that didn't make it in a plane.
