[Kovarex] [2.0.21] Dragging belt over obstacle puts underground too early and no exit w/o undergrounds in inventory MR

[sben]

Bug overview

This bug has 2 variants: either no underground belts are placed, or there are u. belts places but at wrong locations.
The bug happens only if having no underground belts in the inventory, if having a few of them, the placement works.

What did you do? What happened?

Place underground belts - see video.
Setup: drag begin -> empty tiles -> power pole -> belt running in a crossing direction -> empty tiles.

Result is either
- belts but no underground belts are placed
- unconnected belts and underground belts are placed.

What did you expect to happen instead? It might be obvious to you, but do it anyway!

- underground belts to be placed
- no unconnected belts to be placed

Does it happen always, once, or sometimes?

Always

Type 1:

underground-belt-placement-type-1.mp4

(2.08 MiB) Downloaded 38 times

Type 2:

underground-belt-placement-type-2.mp4

(1.13 MiB) Downloaded 34 times

This is still an issue as of 2.0.44.

[sben]

Why is this a duplicate / which post is this a duplicate of?

I searched the all post since Februar 3, 2024 (way before launch of Factorio 2.0) that contain the word "underground", but found none which was is similar.
Also searched for "Missing underground belt" (the error message) looking more far in the past, still no luck.

- most post are about placing underground belts issues while having them available in inventory
. this only happens if no underground belts in inventory :

- all issue posts are about missing exit belt or exit belt has wrong orientation- there are a really lots of duplicates of that, but this is post is different
. this either sets both or none of the underground belt ends :

[Loewchen]

This is indeed unique.

The issue only arises with the obstacle ending with a lateral running belt, two belts will place no underground ghosts and if it starts with non belt entity the entrance is placed at the drag starting point. It works correctly if you use ghosts placement:

[AntiElitz]

The bug is not that the underground ghosts are not placed. That is indeed another bug. If I don't ghost build, ghosts must not be placed. Ghosts must be placed only when I ghost build. The otehr bug is the inconsisten gap size.

Ist shoudl leave exactly a gap before and after the belt to bridge if you have no undergrounds. It shall not place ghosts.

[kovarex]

I tried to replicate it in the current newest version, and it doesn't happen anymore (fixed by some other fixes already in the meantime)

[Loewchen]

I tried to replicate it in the current newest version, and it doesn't happen anymore

You mean an internal version? Because I can still produce every single case in 2.0.47.

[Bilka]

Can also still reproduce in 2.0.48, on commit 7d73a6d - Fixed that transport belt ghost upgrading could generate unexpected undergrounds.

Behaviour is only incorrect if there is more than 1 tile blocked and the last tile is blocked by a perpendicular belt.

[kovarex]

Thanks for the re-bump.
I fixed all of the mentioned examples, and made it generally more consistent (which was related to the core of the issue).
Before, when building without undergrounds and ghosts enabled, it behaved differently when building over obstacle of perpendicular belts (output belt was kept next to the gap), compared to some non-belt obstacle (like chests), in which case it left the edge places empty.
Now it always leaves the edge places empty reagrdless the obstacle, and it never removes the starting belt until the dragging gets over the gap (again, it removed it immediatelly with belts, but only later with other obstacles).