mapbox / mapbox/mapbox-gl-js

Complex isobands causes artifacts in Polygon fill

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Dominant language
TypeScript
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Description

I have a project with about 150 isobands, created using Turf isobands, resulting in complex multipolygons.

When I render these on the map, glitches appear in the multipolygon. This is especially the case if the multipolygon has an “island” inside.

Screenshot 2024-02-01 at 10 13 11

**mapbox-gl-js version**: 3.0.0 - 3.1.2

**browser**: Chrome Version 120.0.6099.216, Safari 17.1

### Steps to Trigger Behavior

1. Create complex Multlipolygon with turf IsoBands
2. add it to the map
3. Glitches appear

### Link to Demonstration
https://jsfiddle.net/h0d1y5qr/3/

In the demonstration I only included one complex multipolygon. I will also attach it here for future reference.

[errornousGeoJson.json](https://github.com/mapbox/mapbox-gl-js/files/14122980/errornousGeoJson.json)

In my Project I have around 150 such complex multipolygons.

### Expected Behavior
I expect the "Island" polygon to have the same color as the other areas in the Multipoly

### Actual Behavior
The "island" polygon display's an artefact.

Thank you!

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the linked JSFiddle reproduction and the attached erroneousGeoJson.json, then trace how the complex multipolygon is rendered as a Polygon fill. Reproduce the island artifact in the listed browser versions and confirm that the island renders with the same color as the surrounding multipolygon without introducing new artifacts.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript, typescript
Domain
computer-graphics, web-dev
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
38/100

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