Update to the latest version of MapLibre Core

[ntadej]

Update to the latest version of MapLibre Core. This PR will probably also contain the Metal integration.

Closes #181

[birkskyum]

What's holding this PR in draft stage?

[ntadej]

We need stable Metal support so I do not plan this to be merged for version 3.0, but more for 3.1 or one of the later ones.

[birkskyum]

@louwers , does the start of the Vulkan implementation indicate that the Metal backend is considered stable now?

[ntadej]

First the 3.0 release will be tagged with the OpenGL 2 backend. Then we can start thinking about Metal integration.

[louwers]

The Metal backend has been considered stable since the MapLibre Native for iOS 6.0.0 release which includes the Metal renderer.

[birkskyum]

@ntadej , if the 3.0 doesn't have this PR, and this PR is breaking (opengl2 sunset), wouldn't it be necessary to bump to 4.0 rather than 3.1?

[ntadej]

That's an interesting question. I think as long as no devices stop working, switching from OpenGL to Metal is not necessarily a breaking change.

My idea was anyways to find a way to allow to toggle between two backends for a while.

[birkskyum]

@ntadej , my concern is not related to Metal. There are ~4.1% of active android phones that doesn't support opengl3/4 yet, so upgrading from opengl2 to opengl3/4 which this PR does could warrant a major release, since this might be breaking on those phones. I don't know the support distribution of opengl for windows / linux desktop users, but i expect there will be some tail as well, albeit maybe small.

[birkskyum]

@ntadej When the dust has settled a bit from the 3.0 release (Great job btw!), then I'm curious to learn what you think of where this core-update fit's into the roadmap - is it after all the 3.1 tickets, or is it more feasible to make this a 4.0 and then catch up on those outstanding issues after?

[ntadej]

For this we also need someone to implement Metal (and potentially Vulkan, but this is optional). Unfortunately I lack the needed knowledge but maybe the experts that have done the initial port can find some cycles to help with it. This would then be 4.0, yes.