clustering groups changes frequently

[wasimshigri]

With a minimum interaction it re-clusters the spots. also the groups are different each time when the map comes back to same location and same zoom level. it should always do the same groupings.

1. There should be a variable for sensitivity which should control the clustering sensitivity on zoom change.
2. algorithm should be updated so that it should do groups same each time for same location and same zoom level.

New Issue Checklist

• I updated Cluster to the latest version.
• I read the Contribution Guidelines.
• x] I read the documentation.
• I searched for existing GitHub issues.

Issue Description

Environment

• iOS Version: [INSERT iOS VERSION HERE]
• Device(s): [INSERT DEVICE(S) HERE]

[matopeto]

I have same issue, i think it is caused by: #130 when for every different zoom/region/positon of map are different anotations :(

[matopeto]

I make video:

RPReplay_Final1610634992.mov

There should be always 34 annotations. mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) is called correctly, with correct clusters and annotations, but on map is not some clusters rendered

Also each minimal map zoom changes regroups all clusters

[rnkyr]

It caused by the fact that mapRects() method builds a list of rects dependant on a viewport

so, if you zoom to a level N, then zoom to a level N + m and then get back to the level N you won't get the same rect, hence you'll get different clusters/pins

is there any suggestion on how to improve this behavior?

[rnkyr]

ok, I was able to improve the overall picture by rounding the scale factor (

Cluster/Sources/Cluster.swift

Line 363 in 3c70568

let scaleFactor = zoomScale / cellSize(for: zoomLevel)

) to the nearest non-zero digit. the function that does that can be found at https://stackoverflow.com/a/32194113/5247504

[matopeto]

But one thing is cluster changing another is non rendered culusers :(