[MC-3756] Entities floating in water don't receive vertical knockback upon being hit

The Bug:

Entities floating in water don't receive vertical knockback upon being hit.

Steps to Reproduce:

Summon a creeper in some water.
Hit the creeper and observe the knockback it receives.

Observed Behavior:

Entities don't receive vertical knockback.

Expected Behavior:

Entities would receive vertical knockback.

Linked issues

duplicates 1

MC-34749 Hopper: java.lang.IllegalStateException: failed to create a child event loop - Caused by AntiVirus / Firewall software Resolved

relates to 1

MC-107353 Ghast fireballs move incorrectly when hit with knockback enchantment Resolved

Comments 22

CubeTheThird 2012-11-25T22:36:38Z

Unable to reproduce.

Anon Ymus 2012-11-25T22:55:49Z

The mob actually goes up a little bit. This makes sense as gravity is at play vertically but not horizontally.

David 2012-11-26T17:37:54Z

I propably wasn't specific enough.

Example 1
When you are normally on the ground and attack a mob with a sword with knockback enchantment, the mob will fly far away and very little high (just like you expected).

Example 2
On the other hand when the mob is in water, you jump into water and swim underwater right under the mob (you look between it's legs) and then attack, you would expect the mob to fly really high into the air and not far away. Instead, it flies in the exactly same way as in the example 1.

If this doesn't help then I'll try to draw it in MS Paint.

EDIT: Also when you use Knockback II its even more visible and even more akward.

CubeTheThird 2012-11-27T00:00:52Z

That is exactly what I did, attack from underwater, and the mob went both vertically (not by much mind you) and horizontally.

David 2012-11-27T10:18:48Z

Well then it seems that you (Mojang) like it the way it is. I always imagined knockback as an extra power which is added to your punch and I imagined a punch to behave close to real-life punch.

I'll try to describe it another way.
Imagine that you have a ball and throw it in front of you (that's example 1), then imagine that you throw a ball above your head (that's example 2). That's how I imagined Knockback to work and how it also make sense to me. If Mojang wanted it to behave like some kind of horizontal teleporter, then I'll accept it (with sad panda face).

12 more comments

CubeTheThird 2012-11-27T12:09:40Z

Out of curiosity, are you refering to knockback 1 or 2?

David 2012-11-27T12:48:29Z

I'm refering to Knockback II, which is on my diamond sword together with Smite (IV level I think).

CubeTheThird 2012-11-27T13:11:20Z

I recreated this with knockback II, and I have to agree that the vertical movement (though existant) seems disproportionately small compared to the horizontal movement. Whether or not this is intended, I am not sure. Next time please be as specific as possible when reporting an issue.

Mike B 2013-01-25T04:46:19Z

Whether or not this is considered a bug or intended, this is visible in version 13w03a.
I also noticed that with knockback II that zombies will most launch horizontally out of the water rather than the proportional vertical movement like CubeTheThird said. It almost looks like they skip across the water like a rock rather than upwards.

Video Proof: http://youtu.be/p-ImtDnYk8k

Operating System: Windows 7
Java Version: 7u11
Minecraft Version: 13w03a

David 2014-01-28T18:48:35Z

Just tested it in latest snapshot in singleplayer creative. It's still there.

David 2014-08-09T09:28:20Z

This is not even close to be fixed. The issue is still there in latest snapshot.

David 2014-10-25T10:08:47Z

Still appears in latest prerelease.

galaxy_2alex 2014-10-25T10:12:38Z

Reopened, thanks

kumasasa 2015-12-06T22:12:05Z

Is this still an issue in the current Minecraft Snapshot 15w49b 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.

Kraif 2018-08-29T22:53:27Z

Confirmed for 1.13.1.

Dobbi 2020-06-11T23:48:09Z

Can confirm this for 1.16 Pre-Release 4

Avoma 2020-12-21T15:04:41Z

Can confirm in 20w51a.

bugsbugsbugs 2021-02-19T19:38:32Z

Confirmed for 21w07a

user-c84db 2021-04-25T09:48:59Z

MC-99640 and MC-102554 should be merged to this report because they're all same issues.

user-c84db 2021-05-22T08:07:20Z

Can confirm for 1.16.5. This also happens with Knockback I or even without Knockback enchantments.

ampolive 2021-09-13T19:47:07Z

Can confirm in 1.17.1.

Avoma 2022-07-02T10:55:55Z

I can confirm this behavior in 1.19, though this ticket requires some amendments in order to accurately state what the problem is here. If it's okay, could I request ownership since the reporter has been inactive for just under two years? I'll make all the necessary changes and will keep this ticket actively updated. Thank you in advance 🙂