MGLLineStyleLayer - Gap Line(s) intersect when angled less than 90º

[riastrad]

On iOS using MGLLineStyleLayer, when setting the .lineGapWidth attribute, you would expect that the gap line that's generated would not intersect. However, if the Polyline you are styling has angles that are less than 90º these lines intersect.

Steps to reproduce

1. Create a polyline with angles that < 90º
2. Style the line using the line-gap-width property
3. Observe that the line gap intersects

Expected behavior

As this is property is often used to generate an 'outline' of a Polyline feature, it would be expected that the exterior lines would not intersect. Here's how a line gap is rendered on other GIS software:

Actual behavior

You get intersecting lines:

iOS Maps SDK

Mapbox GL JS

Configuration

I've confirmed this behavior in both the iOS Maps SDK v4.5.0 and Mapbox GL JS v0.50.0

[stale]

This issue has been automatically detected as stale because it has not had recent activity and will be archived. Thank you for your contributions.

[stale]

This issue has been automatically detected as stale because it has not had recent activity and will be archived. Thank you for your contributions.

[chloekraw]

@mourner would this issue be fixed by mapbox/mapbox-gl-js#8275, and was it / will it be ported to -native?

[mourner]

@chloekraw no, this seems like an unrelated issue.

[stale]

This issue has been automatically detected as stale because it has not had recent activity and will be archived. Thank you for your contributions.