Cancelling redundant packets has to big problems:
* The normal case is to not run in the primary thread.
* For legit players a missed micro move could mean that survivalfly can
not detect ground properly.
Better approaches could be:
* Cancel asynchronous packets if they match the last sent one (only
simple hacks).
* Check for moves passing block borders, request block shapes and such
from the main thread.
* Detect actual cheating or unusual patterns instead.
* Queue packets for processing in the main thread.
Missing:
* Actually detect ACK packets for previous outgoing teleports.
* Do something upon detecting illegal coordinates (asynchronous
disconnect? queue kicking, config).
* In addition to the "distance from set-back" check, we have a check of
the per-move distance for in-air checks, taking account of friction.
* In-air and liquid checks should consume vertical velocity once needed.
* Model vertical velocity "exact", i.e. positive and negative, use an
entry once a sub-check fails, quite strict invalidation of not matching
values, matching against the y-distance directly.
* Vertical accounting has been sharpened for the moment. The new
per-move checking might make it superfluous.
* Remove MediumLiftOff in favor of a LiftOffEnvelope carrying basic
lift-off max-gain/max-height/max-phase, enabling to distinguish between
normal lift-off and liquid near ground.
* Rename others (e.g. sfLastYDist -> lastYDist). Thus breaking internal
naming, adding velocity via MovingData still works, but should behave
slightly differently.
* Fixes (waterwalk with head obstructed, resetting of sfDirty, possibly
others).
Issues.
* Edge cases with velocity, water.
* Lava needs friction, at least with velocity.
* Lostground_edge(ydist < 0.0) ->
bunny with yDistance > 0.0. Need more flags or better model for keeping
past moves information.
* Plain ground misses (layered snow).
* lostground with yDist == 0.0, then seemingly in-air yDist== 0.0, then
bunny/lifft-off (similar to above). Needs better modeling of past moves,
because several lostgorund cases mean "the move has been on ground".
Also includes geting the distance to ground for hack-proof set-back-y.
* Vertical velocity is now matched with a margin, because the client
seems to add randomly.
* Possibly new loopholes/exploits (extreme large moves?).
* Cleanup pending.
* Group selected classes into sub-packages of moving.
* Rename classes.
* Must use LinkedList for velocity entries.
* Prepare SimpleAxisVelocity + entry for use-once accounting.
(Might not be the final naming.)
* Use BlockProperties.collides to use the actual bounds of blocks.
* Don't test for sfLowJump to set allowHop.
* Set head bump margin to match 2-high spots and to prevent lowjump fps.
* Tighten conditions for actual hop.
* Don't x > 1.314 * x.
* Add height, eyeHeight, isHeadObstructed to PlayerLocation.
* lowjump detection: from is higher than to, test both locations.
* Remove bunny reset within lowjump detection (defeated flying bunny).
* Check isHeadObstructed directly in the bunnyHop method.
Issues remaining:
* Moderate acceleration ground to ground, after having landed (+1st).
* Possibly transitions between 2-high and other.
* More edge cases with slowness potion.
This seems to be the same value on ground as with slowness potion and
2-step acceleration. Not possible to squeeze into the ordinary bunny
envelope.
On the fly: add PlayerLocation.isOnGroundOrResetCond.
Slowness+bunny will still not fully work, because we need to model
closer to the client here, i.e. acceleration and friction. Remaining
issues in rough order of naughtiness:
* On-ground friction based speed decrease.
* Increasing of speed, above slowness sprinting speed but below normal
sprinting speed.
* Two-step bunnyhop, having h-speed increase to bunny with two packets.
Similarly acceleration effects when touching ground, not modeled right
by bunny.
* Possibly more.
* Remove early return, as we prefer to know what NCP would allow, at
least until sf changes have stabilized.
* Only count in speed effects for normal running/jumping, not
water/web/blocking/sneaking. Either check potion effects or attributes.
Mainly catches the instant ladder and too large moves, generalize step
to have general "reset" as condition instead of "ground", don't limit by
a distance.
* Not actually a fix for anything we encountered.
* Nailed down blockinteract.visible raytracing issues to bad end-points
for raytracing.
* Also test/prepare logging test-cases for raytracing in general. Not
enabled, because we should have some flag/permission/command to check
before logging ~ 5KB per interact event.
This makes logging all violations potentially useful to use alongside
with the "ncp debug player" command in production environments. The flag
debugonly must be set with at least one backend being activated.
