Add wide vector shader option to Custom Drawable Layer

[stefankarschti]

Introduce a new way to draw lines into the library's CustomDrawableLayer interface, by using a third party shader on the Metal platform.

This shader makes use of instancing, and that is implemented into the toolkit for the Metal backend. OpenGL instancing is not implemented by this PR, but the base interface is common and compatible.

The DrawableBuilder is added two methods to build Wide vector polylines: addWideVectorPolylineLocal and addWideVectorPolylineGlobal. These make use of local (tile) coordinates, and global (geographic) coordinates respectively.

The ExampleCustomDrawableStyleLayerHost class in ExampleCustomDrawableStyleLayer.mm contains the updated examples for adding wide vector polylines through the CustomDrawableLayer interface.

[github-actions]

Bloaty Results (iOS) 🐋

Compared to main

    FILE SIZE        VM SIZE    
 --------------  -------------- 
  +0.4% +74.8Ki  +0.4% +64.0Ki    TOTAL

Full report: https://maplibre-native.s3.eu-central-1.amazonaws.com/bloaty-results-ios/pr-2183-compared-to-main.txt

[github-actions]

Bloaty Results 🐋

Compared to main

    FILE SIZE        VM SIZE    
 --------------  -------------- 
  +0.3%  +365Ki  +0.2% +66.8Ki    TOTAL

Full report: https://maplibre-native.s3.eu-central-1.amazonaws.com/bloaty-results/pr-2183-compared-to-main.txt

Compared to d387090 (legacy)

    FILE SIZE        VM SIZE    
 --------------  -------------- 
   +20% +23.4Mi  +406% +24.3Mi    TOTAL

Full report: https://maplibre-native.s3.eu-central-1.amazonaws.com/bloaty-results/pr-2183-compared-to-legacy.txt

[github-actions]

Benchmark Results ⚡

Benchmark                                                     Time             CPU      Time Old      Time New       CPU Old       CPU New
------------------------------------------------------------------------------------------------------------------------------------------
OVERALL_GEOMEAN                                            +0.0078         +0.0075             0             0             0             0

Full report: https://maplibre-native.s3.eu-central-1.amazonaws.com/benchmark-results/pr-2183-compared-to-main.txt

[stefankarschti]

[stefankarschti]

[louwers]

I hope someone from the Metal team can take a look for an in-depth review.

Can some kind of test be added?

[stefankarschti]

Can some kind of test be added?

@louwers : This is currently only available through the CustomDrawable API, therefore can't be included in the regular render test suite.
The API tests for CustomDrawableLayer currently don't support Metal, so we can't include a relevant test there either, since we only have a Metal shader in place.

[louwers]

@stefankarschti We need some way to at least run the code involved in the Custom Drawable Layer on CI. May I suggest this super dumb 'smoke test' to be added to platform/ios/iosapp-UITests/iosapp_UITests.swift?

    /// Make sure the Custom Drawable Layer does not crash
    func testCustomDrawableLayer() {
        app.windows.children(matching: .other).element.children(matching: .other).element.children(matching: .other).element.doubleTap()
        
        let mapSettingsButton = app.navigationBars["MapLibre Basic"].buttons["Map settings"]
        mapSettingsButton.tap()
        
        let tablesQuery = app.tables
        tablesQuery.staticTexts["Add Custom Drawable Layer"].tap()
        sleep(5)
    }

It only makes sure the Custom Drawable Layer does not crash. Then we can worry about how to test for correctness later.