Mapbox-gl-native: The shape of the polygon will change at different zoomLevel

[yzzhan]

The shape of the polygon will change at different zoomLevel, it's similar to the issue https://github.com/mapbox/mapbox-gl-native/issues/3260

Platform: iOS Simulator 9.0
Mapbox SDK version: ios-v3.7.3

Steps to trigger behavior

Code, coordinates, and screenshots are as follows

    // Add the shape to style
    MGLShape *shape = [MGLShape shapeWithData:geoJSONData encoding:NSUTF8StringEncoding error:nil];
    MGLShapeSource *source = [[MGLShapeSource alloc] initWithIdentifier:@"1" shape:shape options:@{}];
    [self.mapView.style addSource:source];

    // Add layer
    MGLFillStyleLayer *layer = [[MGLFillStyleLayer alloc] initWithIdentifier:@"1-style" source:source];
    layer.fillColor = [MGLStyleValue valueWithRawValue:UIColor.redColor];
    [self.mapView.style addLayer:layer];

    // Locate viewport of MapView to the shape.
    self.mapView.zoomLevel = 15;
    self.mapView.centerCoordinate = CLLocationCoordinate2DMake(50.11312, 8.66866);

      [8.67266, 50.11792],
      [8.67267, 50.11778],
      [8.673, 50.11673],
      [8.673, 50.11673],
      [8.67195, 50.11675],
      [8.67195, 50.11675],
      [8.67185, 50.11674],
      [8.67172, 50.11674],
      [8.67137, 50.11673],
      [8.6713, 50.11673],
      [8.67123, 50.11672],
      [8.67107, 50.11668],
      [8.67104, 50.11666],
      [8.67102, 50.11665],
      [8.67098, 50.11662],
      [8.67098, 50.11655],
      [8.67098, 50.11648],
      [8.67092, 50.11591],
      [8.67086, 50.11542],
      [8.67086, 50.11542],
      [8.6708, 50.11528],
      [8.67076, 50.11518],
      [8.67068, 50.11502],
      [8.67048, 50.11473],
      [8.67042, 50.11466],
      [8.67034, 50.11459],
      [8.67026, 50.11451],
      [8.67021, 50.11447],
      [8.66997, 50.11427],
      [8.6699, 50.11422],
      [8.66969, 50.11407],
      [8.66958, 50.11399],
      [8.66947, 50.11391],
      [8.66878, 50.11341],
      [8.66851, 50.11324],
      [8.66851, 50.11324],
      [8.66859, 50.11319],
      [8.66866, 50.11312],
      [8.66876, 50.11296],
      [8.6689, 50.11278],
      [8.66903, 50.11259],
      [8.66906, 50.11255],
      [8.6691, 50.11251],
      [8.66938, 50.11224],
      [8.66972, 50.11186],
      [8.66976, 50.11172],
      [8.67047, 50.11092],
      [8.67081, 50.11053],
      [8.67087, 50.11048],
      [8.67087, 50.11048],
      [8.67112, 50.11019],
      [8.67134, 50.10997],
      [8.67134, 50.10997],
      [8.66966, 50.1095]

Expected behavior

When scaling a map, the shape of a polygon will not change

Actual behavior

When I zoom in the map, the shape of the polygon changes

[friedbunny]

Can you clarify which version of our iOS SDK you’re using? The v5.0.2 tag refers to an older Android release — the current iOS release is ios-v3.7.3.

[yzzhan]

Sorry for the wrong version because of my carelessness，the correct version is ios-v3.7.3

[JacobJT]

I'm seeing this issue as well. I have a polygon that looks fine. If I zoom too far in, it actually disappears. But this is like close enough a house takes up the full screen, so not a huge issue. The bigger issue is that when I start adding more polygons in real time, sometimes existing polygons get distorted like this.

A couple notes - I am drawing new polygons on the user end. I have a separate layer for the "in progress" polygon. When I'm drawing it, the original polygons don't get affected. However, I have a "new shape" button, which will put the in progress polygon on the layer with the other polygons. It's pressing this that sometimes results in other polygons getting distorted. And not every time, it seems to be based on distance from the other polygons. Perhaps something to do with being partially on a different tile? When it happens though, it affects 90% of existing polygons.

Update - Interestingly, the threshold for the distortions to occur becomes way lower (as in lower zoom value) as larger polygons are added.

[studyroz]

We're suffering this issue as well.

After migrate the classic annotations/delegate APIs to source/shape based APIs, polygons often get distorted when zoomIn or zoomOut.

[JacobJT]

I found the solution to this was ensuring that the coordinates you use for the polygons meet the spec criteria of being a closed loop, i.e. the first and last coordinate should be the same. While the polygon will appear to be drawn correctly, there is obviously some stuff going on under the hood that requires that last point to match, and results in some wonky behavior when it does not.

[lilykaiser]

Great to hear that you resolved your issue @JacobJT ! Closing for now, please reopen if needed