[MC-1207] Head rotates in the wrong direction while riding

The bug

It affects all gamemodes, when you are riding a mob (no minecart or boat) and you look around in this person view, it twists your head backwards if you look in the opposite direction of the mob.

Here is a video demonstrating it:
http://www.youtube.com/watch?v=5zV4kRict30

Code analysis

See @unknown's comment.

Linked issues

is duplicated by 33

MC-2924 Head backwards Resolved

MC-8108 sometimes peoples faces look glitched when riding a pig Resolved

MC-10400 When riding a pig which is riding a minecart, your body spins and your head doesn't. Resolved

MC-10737 Head can be on backwards if riding pig in minecart (doesn't move) Resolved

MC-10866 Riding a pig glitch Resolved

28 more links

relates to 2

MC-79735 Armor Stand passengers rotation displays incorrectly Open

MC-100000 Arms in boat do not rotate correctly while drawing bow/crossbow Open

Attachments

Comments 40

Mortvert (Mort Imert) 2012-11-11T09:41:37Z

I can duplicate this easily.

kumasasa 2012-11-16T23:43:52Z

Confirmed. When riding a minecart or boat the whole player turns when the head turns, but on a pig the pig and player stands still and only the head rotates owl-like.

julian mazer 2013-01-16T04:34:01Z

I Thought that was a feature to make it more like riding like a horse

Javier Juárez 2013-02-10T01:27:38Z

Confirmed on snapshot 13w06a

Ezer'Arch 2013-06-17T14:07:17Z

This is the same of MC-1545.

30 more comments

Itouch2 2014-05-10T20:35:39Z

Confirmed for Donkey in 14w19a.

Jesper the End 2014-08-06T00:53:06Z

confirmed for 14w31a

Samuel Shank 2014-08-07T22:20:26Z

confirmed for 14w32b

[Mod] redstonehelper 2014-08-24T23:11:31Z

Confirmed for 1.8-pre1.

Jesper the End 2014-08-30T12:20:29Z

Confirmed for 1.8-pre3

[Mod] redstonehelper 2014-10-07T21:14:36Z

Confirmed for 1.8.

kasamikona 2014-10-25T17:48:10Z

I can also confirm for 1.8.1-pre3

ColdVolcano 2015-01-01T02:39:20Z

I can confirm for Minecraft 1.8.1 and 1.8.2-pre1

onnowhere 2015-02-20T22:41:34Z

Confirmed 1.8.3

Keighly W 2015-03-09T16:38:47Z

This has happened to me. I'm not sure if it's fixed by now as it only happened yesterday before I logged off, so...yea!

Dylan 2015-04-20T00:45:23Z

Confirmed for 1.8.4, appears to be effective whenever the player is riding any entity, including armor stands and all mobs that weren't mentioned here. It also appears to invert the yaw aspect of the head as well as the pitch.

Sam Bone 2015-05-24T20:32:35Z

Not only for players, I spawned a zombie with my head riding a zombie horse. The head was backewards on it, too!

It makes it hard to take what I was building seriously.

Dylan 2015-07-18T14:16:37Z

Confirmed in 1.8.7.

Dobypeti 2015-08-02T13:13:06Z

Confirmed for 1.8.8.

Swekob 2015-10-26T13:48:23Z

Confirmed for 15w43c.

Swekob 2015-10-28T19:40:22Z

Confirmed for 15w44a.

onnowhere 2015-11-12T20:38:53Z

Confirmed 15w46a 😞

Enoch Fox 2015-12-18T03:59:15Z

Please add that this effects riding all mobs aside from Boats

Void_Concept 2015-12-22T23:45:30Z

Can confirm for 15w51b. This also affects mobs riding other mobs (or Armor Stands in my case)

JUE13 2016-02-13T03:16:31Z

Confirmed for 16w06a

Philipp Koehler 2016-03-05T13:32:35Z

Can confirm for Release 1.9.

David Carlstedt Ringius 2016-04-19T18:33:28Z

confirmed for 1.9.2

FaRo1 2016-06-22T21:25:43Z

Confirmed for 1.10.1.

FaRo1 2016-06-26T11:16:14Z

Before everyone starts adding random entities, I removed the list. And as I was already on it, I changed the description. I'm pretty sure that minecarts and boats are the only exceptions to this, but if there are more, feel free to correct me.

. 2016-09-28T22:18:15Z

Confirmed for 16w39a.

. 2016-11-14T21:05:37Z

Confirmed for 1.11.

. 2017-02-08T23:40:43Z

Confirmed for 17w06a.

. 2017-04-12T21:25:03Z

Confirmed for 17w15a.

JUE13 2017-05-08T14:00:27Z

Confirmed for 17w18b

me4502 2017-05-15T12:50:14Z

So I've been looking into this issue, and it appears to be caused by the rotation offset applied in doRender, in RenderLivingBase. If an entity is riding an entity that extends EntityLivingBase, the 'f' value is modified, which is the rotation point for the body.

This is applied as a global rotation, which breaks head rotations. f2 could be modified, however that's linked to body rotation eventually as well. It appears it'll need to pass extra info through to solve this.

(Everything using MCP names for 1.11.2)

marcono1234 2017-05-16T20:19:28Z

@@unknown to be honest I think the bug is that you can rotate that far at all. Instead the rotation should be restricted like it is currently the case with boats.

Void_Concept 2017-05-17T05:26:52Z

@marcono1234 I disagree with that completely. Yes, specific things like boats should restrict rotation. However there was a use case that I had (years ago at this point, so idr) that would rotate an entity with no AI separately from the entity it was riding.

I'm pretty sure I was attempting to use an armor stand as a marker for where a villager was standing while rotating the villager to face a specific direction. I think I would have had to rotate both the armor stand and the villager to face that direction if I wanted to get it to work correctly. It would be even worse if I had to rotate the armor stand specifically before the villager, otherwise the villager would pop back to whatever direction it is forced to look by what you are suggesting.

me4502 2017-05-18T02:23:56Z

After extensive testing, I can say that the highlighted line in the following image fixes the problem without any loss of functionality: http://i.imgur.com/H06P4AI.png

This is using MCP names, but should be super easy to transfer to MC names.

. 2017-06-08T03:03:16Z

Confirmed for 1.12.

me4502 2017-06-11T05:08:12Z

I can confirm this was fixed in 1.12 using the above code. I had a quick chat to Grum and he confirmed that it was merged in for 1.12, and I've re-ran the tests I ran when I made the patch with vanilla 1.12 and it is working as it should.