Allow annotation views to lie flat against a tilted map

[1ec5]

MGLAnnotationView should have a tiltsToMatchCamera property to complement the rotatesToMatchCamera property added in #9147. The effect we’re after is similar to what you can accomplish with MGLSymbolStyleLayer.iconPitchAlignment. Courtesy of #5245 (comment), here’s a preview of what it would look like when applied to annotation views:

Originally, #5067 introduced a flat property to MGLAnnotationView, off by default, that allowed the view to appear to lie flat against the map as the map tilts. The idea was to match the Google Maps SDK’s GMSMarker.flat property. However, as seen in #5090, all it did was to vertically scale the view, a very different effect.

We backed out the flat option in #5546. #5245 attempted to transform the view the right way to match the map’s transform, but that effort went cold. This issue tracks reviving #5245, in hopes that exposing the map’s transform matrix to the SDK will also enable future improvements for using the SDK with SceneKit.

/cc @fabian-guerra @lilykaiser

[1ec5]

mapbox/mapbox-gl-js#7039 (comment) might be a lead for matching mbgl’s transform matrix. That code is on its face about placing 3D objects in the map scene, but having annotation views lie flat is effectively about treating them as 3D objects as well.

[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.

[1ec5]

mapbox/ios-sdk-examples#111 (comment) links to this gist, which calculates the correct transform matrix by reverse-engineering mbgl’s transform matrix with a different axis orientation.

[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.