sometimes on some systems and drviers time here is not what we
want/expect. it can be in the future. there are reasons so, work
around this and use the timestamp of "now" when we get the event as
opposed to the timestamp given to work around odd weirdnesses and
complaints time went backwards.
@fix
setting a loop time timestamp in the future will lead to all sorts of
bad things. the idea is it was meant to go back a little in time AFTER
some sync/animation etc. event to pretend to be at the time when that
event happend (it just took some time ot arrive at the process) and so
animation and other timelines all agree to be at this time a little
bit in the past. going forwards leads to bad things so disallow it and
complain. this fixes weston in a window problems when it sends
timestamps in the future from weston...
@fix
yes - time went backwards. we get time from the device driver and
vsync events... this is so incredibly wrong ... it should not have
ever happened... but it did and that caused all sorts of bad things to
happen to animators. this guards against that and tries to get the
system clock time and if that doesnt work it just takes last time +
0.901.
@fix
while it requires an extra wakeup from vsync thread -> e and this adds
a bit of jitter, it's mroe reliable in the face of "missed a frame"
timings and doesnt degrade as badly.
after i noticed some jitters, it seesms one thread to listen for vsync
events then to wake up the mainloop can suffer from irregular
scheduling jitters. it seems to be highly depenedent on both gpu
driver and cpu but it seemed the vsync thread itself was more reliably
woken than the mainlooop it then signalled, so merging this back is
just batter. it's configurable via an environment variable so we can
try either right now and see, but default is now to be in main loop.
it was a lot of if cases before now it's an array with min version
parameters and globs for matching drivers etc. - much cleaner and
neater to afdd things to the whtielist now.
as per mailing list discussion about dropping xcb support now. it
hasn't been complete for a long time, thus not recommented for being
turned on. as we are moving to a wayland world xcbmakes even less
sense. as agreed, time to clean up a bit and remove a distraction as
well as not well tested code. this also updates po's too.
@feature
Carsten Haitzler
Vincent Torri
Gustavo Sverzut Barbieri