Feat: Alphanumeric Coordinate Grid on Alternate View

[bijx]

Description:

Adds a coordinate grid to the Alternate View (holding spacebar) using numbers on the X-axis, and letters on the Y-axis. No more "he's attacking you in that—well, the little peninsula thing... next to the island! which island? uhh..." moments when playing with friends. Optimally maps have letters A-J (just like in the Battleships board game) but special maps like Amazon River dynamically resize to only have 2 letters so as to not have too many number columns. This feature overall can be toggled via the settings menu.

Also saw it requested on the official discord a couple times, thought it was a neat idea.

World Map

Scales correctly when zoomed in

Amazon River

Enable/Disable via settings

Screen.Recording.2026-01-17.034212.mp4

Please complete the following:

• I have added screenshots for all UI updates
• I process any text displayed to the user through translateText() and I've added it to the en.json file
• I have added relevant tests to the test directory
• 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:

bijx

[coderabbitai]

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Walkthrough

Added a coordinate grid overlay feature: new translations, a user setting and toggle method, a KeyM keybind that emits a toggle event, and a new CoordinateGridLayer integrated into the renderer to draw alphanumeric grid lines and labels.

Changes

Cohort / File(s)	Summary
Translations resources/lang/en.json	Added three keys: action_coordinate_grid, coordinate_grid_label, coordinate_grid_desc.
Input & Events src/client/InputHandler.ts	Added ToggleCoordinateGridEvent class and coordinateGrid keybind (KeyM). Key handling toggles the setting and emits the event.
User Settings src/core/game/UserSettings.ts	Added coordinateGridEnabled() getter and toggleCoordinateGrid() method to read and flip the stored grid state.
UI: Settings & Help src/client/UserSettingModal.ts, src/client/HelpModal.ts	Added a keybind setting entry for coordinateGrid (default KeyM) in the settings modal and a help-row showing the action and its key in the help modal.
Rendering src/client/graphics/GameRenderer.ts, src/client/graphics/layers/CoordinateGridLayer.ts	Imported and added CoordinateGridLayer to the renderer stack. New layer renders adaptive alphanumeric grid lines and labels, subscribes to toggle events, and respects the user setting for visibility.

Sequence Diagram

sequenceDiagram
    participant User
    participant InputHandler
    participant UserSettings
    participant EventBus
    participant CoordinateGridLayer
    participant GameRenderer

    User->>InputHandler: press KeyM
    InputHandler->>UserSettings: toggleCoordinateGrid()
    UserSettings-->>InputHandler: return new enabled state
    InputHandler->>EventBus: emit ToggleCoordinateGridEvent(enabled)
    EventBus->>CoordinateGridLayer: notify toggle
    CoordinateGridLayer->>CoordinateGridLayer: update visibility state
    GameRenderer->>CoordinateGridLayer: renderLayer(context)
    CoordinateGridLayer->>CoordinateGridLayer: computeGrid() and draw lines & labels

Loading

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~22 minutes

Poem

A grid wakes gently at KeyM's call,
Letters and numbers march across the wall,
Toggle and watch the canvas sing,
Lines and labels in tidy ring,
Quiet guides for every map and hall ✨

🚥 Pre-merge checks | ✅ 3 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main feature: adding an alphanumeric coordinate grid overlay to the Alternate View, which is the primary focus of this changeset.
Description check	✅ Passed	The description thoroughly explains the feature, its implementation, visual examples, and community context. It directly relates to all changes in the changeset.
Merge Conflict Detection	✅ Passed	✅ No merge conflicts detected when merging into main

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

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[ryanbarlow97]

Already mentioned in the discord (and I know you reacted to it already) but going to repeat it here for anyone else:

It would be great to get the letters on the exact edge of the map (worried about ultrawide) and just being too far away from the map

[bijx]

Already mentioned in the discord (and I know you reacted to it already) but going to repeat it here for anyone else:

It would be great to get the letters on the exact edge of the map (worried about ultrawide) and just being too far away from the map

@ryanbarlow97 awesome suggestion, just added that in!

Screen.Recording.2026-01-18.172805.mp4

[ryanbarlow97]

do the lines need to go past the map?

can you do something like this instead

[bijx]

Put back into draft until #2946 is merged so we can make the grid view a hotkey instead of being part of Alternate View

[ryanbarlow97]

(update)

[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@src/client/graphics/GameRenderer.ts`:
- Line 280: The build fails because RailroadLayer is being instantiated with
three args but its constructor requires four; in GameRenderer replace the
instantiation new RailroadLayer(game, eventBus, transformHandler) with a call
that passes the missing uiState as the fourth parameter (use the appropriate
uiState value available in scope), ensuring the RailroadLayer constructor
signature (game, eventBus, transformHandler, uiState) is satisfied.

[bijx]

@ryanbarlow97 I finally got around to fixing this up, it's got keybinds to M now instead of using UserSettings to toggle, and was tested with latest changes

[evanpelle]

when it's active it seems to use about 5% cpu. maybe it's recalculating too frequently?

[evanpelle]

instead of a seperate key, what about always showing it in the alternate view?

[ryanbarlow97]

instead of a seperate key, what about always showing it in the alternate view?

There was a bit of discussion on being able to have this on permanently, as I would want this on during team games to make callouts e.g. “someone has a pixel in you in F12” for example

[scamiv]

i would argue that this mainly improves gameplay for people in voice, making the communication gap to casual players even bigger.

[ryanbarlow97]

i would argue that this mainly improves gameplay for people in voice, making the communication gap to casual players even bigger.

We need to promote voice chat gameplay too

[bijx]

@evanpelle

when it's active it seems to use about 5% cpu. maybe it's recalculating too frequently?

I refactored a bit to use an Offscreen Canvas so it only re-renders when a change is made to the view (camera pan, zoom, etc.). Should be more efficient now!