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DevelopingTom c6c793f6b3 Highlight hovering railroad (#3156)
## Description:


![rail_snap](https://github.com/user-attachments/assets/1dc66dc8-5df8-4826-8a8e-521d72a1f8aa)

The `RailroadLayer` simply displays tiles as instructed by the core
worker. While it's practical for the layer to only care about the tiles,
it also means it has no understanding of railroads as entities (their
paths, connections, or identities).

It also means that the core worker is responsible for rendering tasks
such as tile orientation and construction animation, which is not
expected.

To support ID-based events and better separation of concerns, the
rendering layer needs to be aware of complete railroads. With this
change, the core worker can send the tiles once and subsequently
reference railroads only by ID for all other events.

#### Changes:
- `RailroadLayer` now stores full railroad data instead of only
individual tiles
- `RailroadLayer` is responsible for animating newly built railroads
- Add a new `RailroadSnapUpdate` sent when a new structure is built over
an existing railroad. This event is used by `RailroadLayer` to keep
railroad ID in sync.

- When hovering over a railroad, the render worker is querying the core
worker about overlapping railroads.
Alternatively, RailroadLayer could compute overlaps itself now that it
has full railroad knowledge, but this logic would need to be duplicated
and kept in sync across workers. Keeping a single source of truth in the
core worker is preferred.


#### Edgecases:
- When a structure snaps over a railroad, the original railroad is split
into two new railroads. If the construction animation is still in
progress, instead of resuming the animation at the correct point on the
new railroads, all remaining tiles are rendered immediately
- Previously, `RailroadUpdate` handled both construction and
destruction. This no longer works with `RailroadSnapUpdate`, as event
ordering is now pretty important and IDs may be lost before they are
consumed.
To address this, RailroadUpdate is split in two:
`RailroadConstructionUpdate` and `RailroadDestructionUpdate`.


## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

IngloriousTom

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Co-authored-by: jrouillard <jon@rouillard.org>
2026-02-09 13:37:27 -08:00
..
2026-02-05 12:16:59 -08:00
2026-02-05 12:16:59 -08:00