[MC-95973] Adult Horse/Donkey Pathfinding Issue: 1 block elevations treated as 'non-traversable' terrain in certain configurations Created: 21/Jan/16  Updated: 24/May/16  Resolved: 24/May/16

Status: Resolved
Project: Minecraft: Java Edition
Component/s: None
Affects Version/s: Minecraft 16w03a, Minecraft 1.9 Pre-Release 2, Minecraft 1.9 Pre-Release 3, Minecraft 1.9, Minecraft 1.9.1 Pre-Release 2, Minecraft 1.9.1 Pre-Release 3, Minecraft 1.9.1, Minecraft 1.9.2, Minecraft 16w15a, Minecraft 1.9.3 Pre-Release 1
Fix Version/s: Minecraft 1.9.3 Pre-Release 1, Minecraft 16w21a

Type: Bug
Reporter: Heriberto Rodriguez Jr Assignee: [Mojang] ProfMobius (Thomas Guimbretiere)
Resolution: Fixed Votes: 25
Labels: None
Environment:

Windows 10 Java 1.8.0_25 64 bit


Attachments: PNG File 2016-01-21_21.04.04.png     PNG File 2016-01-21_21.04.45.png     PNG File 2016-01-28_22.13.19.png     PNG File Corral Escape 2016-04-30_14.42.59.png     PNG File Corral Example 2016-04-30_14.42.19.png     PNG File Trapped 2016-04-30_14.27.31.png    
Issue Links:
Duplicate
is duplicated by MC-91732 Leashed adult horses don't walk up fu... Resolved
is duplicated by MC-98201 Horses and Mules dont follow if there... Resolved
is duplicated by MC-98203 Horses and Mules dont jump 1 block hi... Resolved
is duplicated by MC-99773 Horses Can't go up a one block height Resolved
is duplicated by MC-101313 Unsaddled and/or untamed horses canno... Resolved
is duplicated by MC-101349 Horses/Donkeys/Mules Cannot Walk "Uph... Resolved
is duplicated by MC-101378 Leads and moving friendly/nutral mobs... Resolved
Relates
relates to MC-93886 Iron golems failing to jump up single... Resolved
CHK:
Confirmation Status: Confirmed

 Description   

Horses wont jump out of/over 1 block high anything but can use stairs ok! First occurred in snapshot 15w40a and has been there ever since!

What I expected to happen was...:
Horse to be like normal

What actually happened was...:
Horses getting deeper and deeper in my world because once they jump down they don't jump back up! lol

Steps to Reproduce:
1. Make new world in 15w40a or newer and find a horse.
2. Make a hole 1 block deep by whatever width/length
3. push/spawn a horse in the hole and he's stuck. Also if you look around you'll notice all horses getting progressively lower and lower in the world and also because of this all the cave entrances are filled with horses lol!

Issue started appearing in 15w40a.



 Comments   
Comment by [Mod] redstonehelper [ 22/Jan/16 ]

Confirmed for adult horses, not for baby horses.

Comment by Julia Spencer [ 18/Feb/16 ]

I can confirm this issue in Minecraft 1.9 -pre2/snapshot.

A better title for this bug might be "Adult Horse/Donkey Pathfinding Issue"

The pathfinding AI for adult horses seems to treat 1 block elevations as "non-traversable" terrain.

– -- – --

Method:
1. Created new 1.9-pre2 world.
2. Found horses.
3. Dug 3x3 pit 1 block deep, adult horses (tamed, untamed) were unable to leave pit on their own even after considerable time. Foals (child horses) were able to enter and leave normally.
4. Also tested with lead - could not pull adult horse out of 1 block deep pit.
5. Also tested with stairs around edges of 3x3 pit - adult horses were able to enter and leave normally.

Comment by Kevin Richey [ 18/Feb/16 ]

Confirmed with Minecraft 1.9 Pre2.
I had two adult donkeys and one adult horse on leads at the same time, while riding a mule. The mobs on leads would not jump up one block to follow. This is very bad for me as my donkeys are loaded with goods and I have a very long trip back to home base.

Comment by Joshua Cantrell [ 20/Feb/16 ]

Yeah.. really hope this can be fixed before 1.9 proper

Comment by Julia Spencer [ 24/Feb/16 ]

Still present in Minecraft 1.9 Pre3

Method:
1. Create new 1.9-pre3 world.
2. Found horses (note: horses found naturally in world and horses spawned form spawn egg are equally affected.)
3. Dug 3x3 pit 1 block deep, adult horses (tamed, untamed) were unable to leave pit on their own even after considerable time. Foals (child horses) were able to enter and leave normally.
4. Also tested with lead - could not pull adult horse out of 1 block deep pit.
5. Also tested with stairs around edges of 3x3 pit - adult horses were able to enter and leave normally.

Comment by Julia Spencer [ 29/Feb/16 ]

Confirmed for Minecraft 1.9

Tested using methods listed above.

Comment by Joshua Cantrell [ 29/Feb/16 ]

Sad to see this one make it into live

Comment by Heriberto Rodriguez Jr [ 29/Feb/16 ]

Extremely sad to see such a game breaking bug made it into the 1.9 release! I was expecting a pre release 5 but I guess not so My 1.9 playthrough will have to wait now! Pls Mojang can you fix this asap?

Comment by McDodge34 [ 29/Feb/16 ]

At the same time, this bug can be helpful, you can park your horse anywhere, just dig a 4x1 deep hole and you can park it there

Comment by Julia Spencer [ 10/Mar/16 ]

Confirmed for Minecraft 1.9.1-pre2 using the method I described above in a newly generated 1.9.1-pre2 world.

Changes to pathfinding code in pre2 do not seem to have affected this issue. The problem with Horse and Donkey pathfinding "AI" remains.

Comment by Julia Spencer [ 11/Mar/16 ]

Confirmed for Minecraft 1.9.1-pre3 using the steps listed above.

Comment by Julia Spencer [ 11/Mar/16 ]

While testing snapshots for a related issue, I pin-pointed the snapshot that this issue first appeared in.

The last snapshot that horse pathfinding worked correctly in was 15w39c.

Horse pathfinding failed as described in this issue (MC-95973) in snapshot 15w40 and above. (15w40b etc.)

Knowing the release that the issue appeared in might be helpful to the developers. Could a note be added to the description?

Comment by Heriberto Rodriguez Jr [ 14/Mar/16 ]

Edited the description to show the snapshot it first started in, sorry it took so long everyone!

Comment by Socks [ 30/Mar/16 ]

confirmed for 1.9.2 with horse donkey and mule (probably 1.9.1 as well)

Comment by Julia Spencer [ 11/Apr/16 ]

Confirmed still present in Snapshot 16w15a.

The changes to the pathfinding code had no effect on this issue. Tested with Horses and Donkeys.

Comment by John Peaden [ 21/Apr/16 ]

Fixed in the 1.9.3 pre-release. Thanks, ProfMobius.

Comment by Jennifer [ 27/Apr/16 ]

Not fixed. It is still occurring.
Seen it on 2-different computers; 1 is Windows 7, the other is Windows 10.
Windows 7 version is 1.9.2
Windows 10 version is the 1.9.3 Pre-release.

Comment by [Mod] redstonehelper [ 29/Apr/16 ]

Which version exactly? How exactly can you reproduce this bug?

Comment by Julia Spencer [ 30/Apr/16 ]

redstonehelper,

I believe the original issue has been corrected as of 1.9.3-pre1. Horses now move naturally around (most*) terrain as expected, and also horses can now be pulled using leads across all terrain as expected.

I said "most" as there is a small corner case in which Adult Horse/Donkey pathfinding works differently than it did prior to snapshot 15w40a.

In 1.9.3-pre2:

If a Horse or Donkey is in a 2 x 2 "hole", it will not leave such an area on its own. It can be pushed out by the player or another animal. It can be pulled out by lead. But it will not "autonomously" leave.

(See Screenshot: "Trapped", these 4 animals can not leave the 2x2x1 areas without outside help.)

This is also the case for 2 x 4, and 4 x 2 holes – horses will not leave these areas without the intervention of the player or another creature.

(See screenshot: "Corral Example", The two donkeys and the gray horse will never leave their 1 block high stone corral – but watch the white horse in the larger 4x4 area.)

Larger spaces, such as the 4 x 4 enclosure will allow the horses to navigate freely.

(See screenshot: "Corral Escape", The white horse in the 4 x 4 area will walk out unassisted in a very short period of time.)

I could submit this corner-case as a "new issue" if the moderators or ProfMobius (Thomas) would like – though, it really doesn't impact gameplay.

Comment by [Mod] redstonehelper [ 01/May/16 ]

I could submit this corner-case as a "new issue" if the moderators or ProfMobius (Thomas) would like – though, it really doesn't impact gameplay.

Please do.

Comment by John Peaden [ 01/May/16 ]

Great findings, Julia Spencer. I hadn't originally noticed these myself.

I would say it's still the same issue--just change the title to "1 block elevations treated as 'non-traversable' terrain in certain configurations" or something to that extent. It still impacts gameplay considering that the behavior is not the same as it was pre-1.9.

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