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* anholt
really wonders what zink_kopper_present_readback is supposed to do.
<zmike>
zink_kopper_acquire_readback acquires the swapchain for readback, zink_kopper_present_readback restores the swapchain to its previous state
<anholt>
so present is release
<anholt>
but also, it seems to queue a present
<zmike>
hm not quite
<zmike>
yes, that's correct
<zmike>
acquire has to shuffle through the swapchain images to reacquire the last-presented image
<zmike>
and present re-presents it
<anholt>
wait, why would you need to shuffle through?
<zmike>
because there's no api to request a specific image
<anholt>
what's the circumstance that you need the last-presented image, though?
<zmike>
basically just piglit tests for swapchain readback
<anholt>
(context: I'm trying to debug why buffer age is completely broken)
<zmike>
ah you brave soul
<anholt>
if there are any piglit tests assuming that reading the back buffer gives the last presented image's contents without checking buffer age, that would be broken.