MC-8701Creeper AI update lag / walking into hole
Creepers Have AI bug that they had before 1.3 update and in some 1.4 snapshots (it was fixed before 1.4 release).
Their AI is lagging and they does not interact properly with environment/cats/damage.
You can reproduce it by putting Creeper after a Zombie in water canal with Snow Golem (Screenshot #2). If it starts to go against the current, it will still walk in that direction after leaving the water ignoring pathfinding and cats.
Creepers on the first screenshot walk into the void when they start fighting stream.
On the second screenshot Skeleton that was shot by Snow Golem in the stream avoid the hole. Creeper doesn't.
Linked Issues
Created Issue:
Creeper AI Broken (Again)
Creepers Have AI bug that they had before 1.3 update and in some 1.4 snapshots (it was fixed before 1.4 release).
Their AI is lagging and they does not interact properly with environment/cats/damage.
You can reproduce it by putting Creeper in water canal. If it starts to go against the current, it will still walk in that direction after leaving the water ignoring pathfinding and cats.
Creepers on the screenshot walk into the void when they start fighting stream.
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Creepers Have AI bug that they had before 1.3 update and in some 1.4 snapshots (it was fixed before 1.4 release).
Their AI is lagging and they does not interact properly with environment/cats/damage.
You can reproduce it by putting Creeper in water canal. If it starts to go against the current, it will still walk in that direction after leaving the water ignoring pathfinding and cats.
Creepers on the first screenshot walk into the void when they start fighting stream.
On the second screenshot Skeleton that was shot by Snow Golem in the stream avoid the hole. Creeper doesn't.
Creeper AIBroken (Again)Creeper AI lagging
Creeper AIlaggingCreeper AI update lag
Creepers Have AI bug that they had before 1.3 update and in some 1.4 snapshots (it was fixed before 1.4 release).
Their AI is lagging and they does not interact properly with environment/cats/damage.
You can reproduce it by putting Creeper
in water canal. If it starts to go against the current, it will still walk in that direction after leaving the water ignoring pathfinding and cats.Creepers on the first screenshot walk into the void when they start fighting stream.
On the second screenshot Skeleton that was shot by Snow Golem in the stream avoid the hole. Creeper doesn't.
Creepers Have AI bug that they had before 1.3 update and in some 1.4 snapshots (it was fixed before 1.4 release).
Their AI is lagging and they does not interact properly with environment/cats/damage.
You can reproduce it by putting Creeper after a Zombie in water canal with Snow Golem (Screenshot #2). If it starts to go against the current, it will still walk in that direction after leaving the water ignoring pathfinding and cats.
Creepers on the first screenshot walk into the void when they start fighting stream.
On the second screenshot Skeleton that was shot by Snow Golem in the stream avoid the hole. Creeper doesn't.
Creeper AI update lag / walking into hole
is duplicated by
Is this still a concern in the current Minecraft version 1.6.2 / Launcher version 1.1.3 ? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.
duplicates
is duplicated by
relates to
duplicates
relates to
If a Skeleton/Creeper flees from a nearby wolf/cat and gets transported away (e.g. by a water stream) before reaching its destination, the 'escape mode' will lock: It will always try to walk towards the block it was heading to before being moved, no matter how far away, ignoring any obstacles such as walls, holes and other wolves/cats on the way.
The setup you see in the screenshots illustrates the bug. The skeletons get spawned and run away from the wolf to the right. Using trap doors, they are tricked to fall into the water stream and get transported away to the far right. Notice how they fight the current, apparently still in 'escape mode', however without any path or visual contact to the wolf they are running from. As soon as they drop to the floor, they run straight back to the left, ignoring the other wolves on their way. When they reach the block below the water source they initially fell on (red marker), they start jumping and spinning. Finally, after some time, normal AI kicks back in and they stop jumping and eventually wander off.
Exactly the same applies to creepers and cats (see fourth screenshot). Notice that if you were to dig a hole (to the void) in their way, they would walk into it, as they would walk straight against any wall/block you place between the drop point and the red marker. Also note that this issue seems similar to MC-8701, however I wasn't able not reproduce the bug without wolves/cats as shown there.
Apparently, the mobs never even realize that they move away from their original path. It seems like this 'escape route' (i.e. to a block on the platform to the far left) is calculated as soon as they realize the presence of the wolf/cat. They then start walking from block to block of the route, but seem unaware that their Y-Position changes as they fall, so they continue walking towards the next block of the escape route. The water pushes them in the opposite direction no matter how hard they fight the current, and so they just keep on running endlessly.
This is a severe issue in scenarios where said mobs are automatically directed or separated using their AI, i.e. in mob farms/sorters. I stumbled upon this in a survival world where the mobs get transported ~40 blocks away from an AI-based farm (which works like the setup in the screenshots). Took quite some time to figure out why they keep hugging a solid stone wall!
Update:
I have been digging into the code using MCP, apparently there is a method that makes Creepers and Skeletons repeatedly check whether they should keep on running (EntityAIAvoidEntity.continueExecuting()), however it only cancels if the target block is reached or escape path becomes unavailable due to being stuck:
public boolean continueExecuting() { return !this.entityPathNavigate.noPath(); }
One could simply extend the condition to also check if the distance to the next PathPoint on the route (i.e. the block right in front of the mob) is within a reasonable range: The square distance should not exceed 2 blocks, and even in cases of extreme server lag will probably never exceed 10 blocks:
if (this.entityPathNavigate.noPath()) { return false; } Vec3 p = this.entityPathEntity.getPosition(this.theEntity); return this.theEntity.getDistanceSq(p.xCoord, p.yCoord, p.zCoord) < 10.0D;
I can confirm this, I have a lot of cats and a Creeper will sometimes ignore them chasing me, going right down the middle, only to stop and turn around, running off when they should have done it a lot sooner (before even getting close to the cats). Hopefully this makes sense.
I have the same problem in 1.4.7. I have a music disc farm and the creeper's pathfinding with not recognize the 200 block fall if they are fighting the water current. They also have a extremely delayed response time or not react to cats at all. If needed I can post a video.
EDIT: the creepers in my trap fall on to solid ground.
was related:
MC-8007About the drop-to-void -case shown in screenshot: There is/was another bug report about mobs no longer considering the drop to void as a dangerous drop (
MC-3151); i.e. they think a hole to void would be just flat ground. Thus, when they drop from the water stream, they may still have their desired target location somewhere in the upstream direction, and try to move towards there. Unfortunately, there is (for them) an invisible drop to void on the way...(Alas, that
MC-3151was considered a feature request instead of bug, since normal maps aren't supposed to have holes into void.)I tried this out without the void, and noticed that if they try to push against the current (as if wanting to move somewhere, like on the glass blocks) and they fall below, they go under where they wanted to go and jump up and down in circles for roughly ~5 seconds before stopping and going somewhere else. I once again tried with lava this time instead and they just dropped into the lava, so it seems they AI isn't updating fast enough for them to avoid the danger or to update their path finding. (Like them going under the glass and going in circles before realizing they can't get to the block above.) Lastly, I see this sometimes with mobs, if I break a block they were moving to stand on, they drop into the hole and jump up and down in circles for a bit before stopping.
Basically to sum it up, like Markku mentioned above, their AI isn't updating fast enough, this is what I personally think. I may be wrong, someone correct me if I am.
Joss Eden, that's right. It is AI update lag.
Markku, the environment doesn't matter. If there will be a wall instead of a hole to the void, the would just bump into the wall.
Since 13w07a they're acting more like in 1.4.7, but the lag is still there.
They will walk 3 blocks before the AI update tell that they are not in the stream.
You can reproduce it easily using Snow Golem like on the second screenshot. Put Creeper right after a Zombie, and it will start fighting the stream.
Skeletons doesn't have that lag and they react instantly, bypassing the hole.
In 13w10b they react a bit faster but not as good as skeletons and still walk in the holes
"Lastly, I see this sometimes with mobs, if I break a block they were moving to stand on, they drop into the hole and jump up and down in circles for a bit before stopping."
As I have recently been working on the path finding / path following code, I have figured out why mob may end up spinning around or jumping at a spot when a block along the path has been removed (or added) (un)suitably. The AI does not observe changes in the surroundings (and should not do so, either, it would be quite the task), and the path following routine is so simple that it does not check if the path is still valid or matches the environment at the time of reaching each block. So, when it reaches a spot that has changed after the path was calculated, it will keep on trying to reach the next way point for a while. (It does have a check for not being able to get anywhere over a period of time while trying to follow a path.) (I consider the lack of such checking as a bug, but thus, it should be another issue. Considering that the path following has two other issues in it, I'm not bothering until/if I get them all fixed.)
This does not directly affect the current issue, but explains that particular part of a previous comment.
Is this still a concern in the current Minecraft version 1.7.2 / Launcher version 1.3.4 ? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.
This is still present present in 1.7.2 but is less common.
Is this still a concern in the current Minecraft version 1.7.4 / Launcher version 1.3.8 or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.
This is not a duplicate of
MC-3151(not detecting the void drops), but more of a delay in AI, causing many kinds of issues, one of them being not noticing falls into any kind of holes, including ones that do not go to void. Earlier comments have a bit of elaboration. That is, fixing either issue alone will not fix the other.Ok, sorry for the noise.
It seems that this is still in effect in 1.7.5, at least in survival, both zombies and creepers walked straight off a deep fall after falling from the stream (using similar arrangement as in the screenshots). Seems that skeletons stopped immediately after falling from the water stream.
(As a side note, all 3 monster types sunk into the ground one block's worth, every single time they dropped from the stream; client-side visual bug only; their hit boxes were where they should be.)
Is this still a concern in the current Minecraft version 14w18a / Launcher version 1.3.11 or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.
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