Polygon annotations flicker when zooming

[captainbarbosa]

Steps to reproduce

1. Create a polygon annotation and add it to an MGLMapView.
2. Return a color from -mapView:fillColorForPolygonAnnotation: to give the polygon annotation a color.
3. Zoom in and out of the map and observe flickering.

This issue reproduces when running the companion ios-sdk-examples project: https://github.com/mapbox/ios-sdk-examples/blob/master/Examples/Swift/PolygonAnnotationExample.swift

(Caught in mapbox/ios-sdk-examples#225)

Expected behavior

The polygon annotation should not flicker when zooming in/out.

Actual behavior

The polygon annotation flickers, as shown here: https://gph.is/2x9hWPe
(I would embed here but GitHub compressed the gif too much to see the issue)

Could this possibly be related to #12790?

Configuration

Mapbox SDK versions: All recent versions up until v3.7.8.
iOS/macOS versions: iOS 11.4.1
Device/simulator models: iPhone X, physical device
Xcode version: 9.4.1

[mollymerp]

good call @captainbarbosa – I can reproduce this in GL core 🙃 I think this is a combination of overdraw due to prefetching and the same clipping issue in #12790. The former might be fixed by adding a similar condition as I did here #12529

[mollymerp]

consolidating this issue with other related ones over at #12981