[kovarex] [16.20] Items on belt jump ahead when placing nearby belts

[Lungjuice]

When I replace belts near (about 5 tiles in radius I think) loosely packed items on the same bus they jump forward slightly. (I expect items on belts that aren't on the same belt to not be shifted around like there was some sort of strong wind)
The amount they jump is significantly less for the yellow belt compared to the blue belts.

Here is the issue in action https://youtu.be/3mitNzETnUg (you will probably want to look at it in 1080p full screen to most easily see it)
EDIT: Look at my reply after this or go directly to the new video instead at https://drive.google.com/open?id=1vOeD0 ... ck4jTB6hgq

To reproduce:
1. Have some flow of items on a 4 wide same speed parallel belt bus that isn't being significantly being filled (like 10% density or less)
2. replace one of the belt tiles with a different speed belt
3. the very moment that you replace it all items on belt tiles near that belt for the couple seconds will get that jump when they enter an area around it (approximately 3 to 5 tile radius I think)

Seems to happen all the time for that situation in the video and save file, though I haven't done any testing yet in other locations.

EDIT: The google drive folder link is now in the follow up reply below
I tried uploading the video here but .mkv isn;t allowed, it took about 8mins to up,load and it is getting late so I will just change the extension tomorrow and upload it if you need it.
The forums just said "Sorry, the board attachment quota has been reached." when I tried to upload the save . I will have to do that tomorrow then.

[Lungjuice]

Here a google drive folder with the mp4 of it happening, save and log file.
https://drive.google.com/open?id=12dEkh ... R_KeGM0tbG

[TheSuperSewcio]

Very strange belt bug, just look at the first items on a belt. Sometimes happens when merging 2 belts into 1.
Tested: 0.16.22, works with all 3 belt types.

Video:
https://youtu.be/JYZAFphl7Nw

Merged...

[Loewchen]

Ref: 54693

[Lungjuice]

Ref: 54693

Yeah it is likely a duplicate of the cause of that, you can see what areas get affected more clearly if you turn on "show-transport-lanes" in the debug menu. Interesting that nearby lanes without nearby merging get affected by their neighbours actions.
In 8 lane main bus situations the jump/creep seems to have a diameter of 5 no including diagonals: _ is unaffected, 0 is affected, X is affected tile that changed
__0__
_000_
00X00
_000_
__0__

[impetus maximus]

what problems does this cause?

[Lungjuice]

It's pretty minor really, like a "technically not intended but generally no one cares if a few items on belts get pushed ahead up to a tile every now and then" kind of bug. Possibly the kind of thing that gets fixed with a +/- 1

[impetus maximus]

that's why i was asking. i see multiple people reporting it, but no complaints of any problems it's causing.

[TheOnefinn]

It probably makes little difference to belts as a transport medium, but it really hurts belts as a communication medium, I was experimenting with encoding information in belts and the conclusion I came to is it’s just not worth playing with in its current form.

If nothing else it just looks kinda ugly to have items randomly moving around on belts, and items travelling faster through splitter or wired belt blocks

[kovarex]

Should be fixed for the next version.

[MagmaMcFry]

I'm curious, what caused this?

[kovarex]

Order of updates.
The belt segment activated by the newcoming item was activated and updated after the new item arrived to it. So the item moved once again as part of the update of the new segment.