5.5.0 is not respecting line-dasharray

[pappalar]

line-dasharray stopped working in Mapbox SDK 5.5.0.

https://docs.mapbox.com/mapbox-gl-js/style-spec/#paint-line-line-dasharray

example layer:

{
      "id": "my-id",
      "paint": {
        "line-color": "rgba(255, 255, 255, 255)",
        "line-dasharray": [
          0.006666667,
          1.3333334
        ],
        "line-width": 9
      },
      "layout": {
        "line-cap": "round",
        "line-join": "round",
        "visibility": "none"
      },
      "source": "mysource",
      "type": "line"
    },

Steps to reproduce

1. Draw a line with dasharray in 5.4.0. The line is dotted
2. Update SDK to 5.5.0
3. Draw the same line: The line is not dotted anymore

Expected behavior

• Style Specification are kept

Actual behavior

• SDK Bug in style specs reading

Confguration

Mapbox SDK versions: 5.5.0

[pappalar]

My supposition is that #15756 might be breaking it?

[pappalar]

@julianrex same for this issue. Please let me know if I am opening issues in the wrong repo and I will move them to the main one!
Thanks for the explanation

[pappalar]

Hello! Upping this because is business critical for me, but I can't rollback to 5.4.0 due to the other issues with insets in that version.

[julianrex]

@racer1988 moving this ticket to the gl-native repo as it appears to be a core rendering issue.

/cc @tmpsantos

[pappalar]

More investigation shows that:

It works in 5.4.0
it works on Android latest release.

so it's a 5.5.0 issue.

[julianrex]

Thanks for the clarification @racer1988.
🤔

[tmpsantos]

@racer1988 thanks for reporting and bisecting the issue. We will have a look monday. @julianrex thanks for flagging. I'm surprised our render tests have not caught this regression. :-(

[astojilj]

@racer1988 ,
Could you please share the full layer style to be used to reproduce the same as on screenshots?

{
     "id": "my-id",
     "paint": {
       "line-color": "rgba(255, 255, 255, 255)",
       "line-dasharray": [
         0.006666667,
         1.3333334
       ],
       "line-width": 9
     },
     "layout": {
       "line-cap": "round",
       "line-join": "round",
       "visibility": "none"
     },
     "source": "mysource",
     "type": "line"
   },

Apart from "visibility": "none" I don't see where the blue color is coming from. Some more layer code would help. Similar tests that we have in automatic render tests don't show the problem.

#15756

Did you identify some specific issue in the patch or bisecting showed that it is the one causing the regression?

[pappalar]

@astojilj for number #15756 I just guessed. It seems to be the only change in the changelod between version 5.4.0 and 5.5.0 that changes the rendered/style part of the core.

I haven't seen any other issue/change talking about rendered/style, so I suggested that might be a good place to start bisecting the regression.

---

Here is the style we use to draw either the normal line and the dashed line with white border and blue content.

The same style is used across iOS and Android and works until iOS version 5.4.0 (and still works on Android)

{
      "id": "white-border-normal",
      "paint": {
        "line-color": "rgba(255, 255, 255, 255)",
        "line-width": 9,
        "line-opacity": {
          "stops": [
            [
              14,
              1
            ],
            [
              15,
              0.6
            ]
          ]
        }
      },
      "layout": {
        "line-cap": "round",
        "line-join": "round",
        "visibility": "none"
      },
      "source": "theline",
      "type": "line",
      "filter": [
        "==",
        [
          "get",
          "custom_line_type"
        ],
        "normal"
      ]
    },
    
    {
      "id": "blue-normal",
      "paint": {
        "line-color": [
          "case",
          [
            "to-boolean",
            [
              "get",
              "selected"
            ]
          ],
          [
            "rgba",
            0,
            64,
            148,
            1
          ],
          [
            "rgba",
            0,
            88,
            202,
            1
          ]
        ],
        "line-width": 6,
        "line-opacity": {
          "stops": [
            [
              14,
              1
            ],
            [
              15,
              0.6
            ]
          ]
        }
      },
      "layout": {
        "line-cap": "round",
        "line-join": "round",
        "visibility": "none"
      },
      "source": "theline",
      "type": "line",
      "filter": [
        "==",
        [
          "get",
          "custom_line_type"
        ],
        "normal"
      ]
    },
    {
      "id": "dashed-border",
      "paint": {
        "line-color": "rgba(255, 255, 255, 255)",
        "line-dasharray": [
          0.006666667,
          1.3333334
        ],
        "line-width": 9,
        "line-opacity": {
          "stops": [
            [
              14,
              1
            ],
            [
              15,
              0.6
            ]
          ]
        }
      },
      "layout": {
        "line-cap": "round",
        "line-join": "round",
        "visibility": "none"
      },
      "source": "theline",
      "type": "line",
      "filter": [
        "==",
        [
          "get",
          "custom_line_type"
        ],
        "dashed"
      ]
    },
    {
      "id": "dashed",
      "paint": {
        "line-color": [
          "case",
          [
            "to-boolean",
            [
              "get",
              "selected"
            ]
          ],
          [
            "rgba",
            0,
            64,
            148,
            1
          ],
          [
            "rgba",
            0,
            88,
            202,
            1
          ]
        ],
        "line-dasharray": [
          0.01,
          2
        ],
        "line-width": 6,
        "line-opacity": {
          "stops": [
            [
              14,
              1
            ],
            [
              15,
              0.6
            ]
          ]
        }
      },
      "layout": {
        "line-cap": "round",
        "line-join": "round",
        "visibility": "none"
      },
      "source": "theline",
      "type": "line",
      "filter": [
        "==",
        [
          "get",
          "custom_line_type"
        ],
        "dashed"
      ]
    },

[astojilj]

@racer1988
The issue seems to be related to wrong evaluation of this code - custom_line_type is apparently evaluated to normal. How is it set in your code?

[
        "==",
        [
          "get",
          "custom_line_type"
        ],
        "dashed"
      ]

[pappalar]

@astojilj there is another similar example in mapbox/mapbox-gl-native-ios#62
that does not use the custom parameter, so that might give you another clue in where the issue might be

as this was working until 5.4.0, I don't believe this is a issue with my style.

To set this I create a MGLPolilyneFeature and then I set the attribute

attributes["custom_line_type"] = "dashed"

before assigning the shape to the source and enabling the layers

[astojilj]

We don't have render tests combining round line-cap and line-dasharray and this wasn't caught by tests.

Related to 84f2ff1

Reproducible using iOS Demo App, using patch:

diff --git a/platform/ios/app/MBXViewController.m b/platform/ios/app/MBXViewController.m
index 82a68e074..667c27149 100644
--- a/platform/ios/app/MBXViewController.m
+++ b/platform/ios/app/MBXViewController.m
@@ -1484,6 +1484,9 @@ - (void)styleRouteLine
     baseRouteLayer.lineOpacity = [NSExpression expressionForConstantValue:@0.5];
     baseRouteLayer.lineCap = [NSExpression expressionForConstantValue:@"round"];
     baseRouteLayer.lineJoin = [NSExpression expressionForConstantValue:@"round"];
+    NSExpression *constantExpression = [NSExpression expressionWithFormat:@"{4, 4}"];
+    baseRouteLayer.lineDashPattern = constantExpression;
+
     [self.mapView.style addLayer:baseRouteLayer];
 
     MGLLineStyleLayer *routeLayer = [[MGLLineStyleLayer alloc] initWithIdentifier:@"style-route-layer" source:routeSource];
@@ -1492,6 +1495,7 @@ - (void)styleRouteLine
     routeLayer.lineOpacity = [NSExpression expressionForConstantValue:@0.8];
     routeLayer.lineCap = [NSExpression expressionForConstantValue:@"round"];
     routeLayer.lineJoin = [NSExpression expressionForConstantValue:@"round"];
+    routeLayer.lineDashPattern = constantExpression;
     [self.mapView.style addLayer:routeLayer];
 }
 

[kkaefer]

Fix is in #15947

[pappalar]

@julianrex How will the GL-native fixes end up in iOS SDK now?

Will this be in 5.6.0?

[julianrex]

@racer1988 Yes it is!

/cc @jmkiley