Line rendered with incorrect curvature in globe projection

[akos-fulop-public]

maplibre-gl-js version: 5.16.0

browser: Firefox, Safari

Steps to Trigger Behavior

1. Run linked example
2. Place a straight object on your screen over the purple line at the center
3. Note curvature of the line

Link to Demonstration

https://jsbin.com/gumiqalade/edit?html,output

Expected Behavior

The line is centered in a globe projection should be rendered as straight

Actual Behavior

The line curves away from the equator

[HarelM]

I believe this is by design, if you move the map and rotate the globe the line changes its curvature.
If you don't want to see this then you should probably use mercator instead of globe.
Also as you zoom in globe change to mercator.
But this line is pretty big :-)

[akos-fulop-public]

Hi Harel,
I might have phrased the issue wrong, but my problem is that lines drawn on the globe don't seem to be geodetic. The issue is more visible with

coordinates: [
    [
        20,
        65
    ],
    [
        -55,
        60
    ]
]

I'm working on visualizing aircraft paths, so that's why the line is so long.
What I think is happening is the line is calculated to be straight on a mercator projection, and then just wrapped around the globe. But this is incorrect, as it doesn't follow the shortest paths, i.e. great circles.

Here's an illustration of what I would expect (with roughly the same coordinates as I gave in this comment.

And this is what maplibre does:

The difference is clearly visible at Iceland.

[HarelM]

I see your point.
Yes, this mostly follow mercator and probably why this issue exists.
I saw that turf recently added some stuff related to great circles, so you might want to create a route with more points that follows the shortest path using turf code and feed that to maplibre to show.
Generally speaking, this should be handled internally, so you are welcome to open a PR to resolve this.