Turfjs
Issue with turf.difference behavior between Turf.js v5.16 and v6.5 (and recent versions)
I’ve encountered a discrepancy in the behavior of the turf.difference function between Turf.js versions 5.16 and 6.5.
In version 5.16, using turf.difference to subtract holes (multipolygon) from a world polygon works as expected, producing the correct result. However, when I update to version 6.5, the output is incorrect or differs from the expected result.
Steps to Reproduce:
Use the following world polygon as the outer boundary:
const worldPolygon = turf.polygon([[
[-180.0, 89.0],
[-180.0, -89.0],
[180.0, -89.0],
[180.0, 89.0],
[-180.0, 89.0]
]]);
Use the multipolygon as the holes:
const multiPolygon = turf.multiPolygon([
[
[
[
1.5848481682316446,
48.31986594114687
],
[
1.8832104345803926,
48.42342314863003
],
[
1.8734490264407953,
48.31243967954646
],
[
2.0474541685456376,
48.433892157002646
],
[
1.9407386741551667,
48.44339036470831
],
[
2.139324407980982,
48.51231658749331
],
[
2.140165825025228,
48.54733551405033
],
[
2.005794737854104,
48.62423252424017
],
[
2.14201346746852,
48.62423252424017
],
[
2.1464195901569383,
48.80761089514678
],
[
2.017641560842897,
48.71825624766248
],
[
1.9156353862877893,
48.79208242133859
],
[
1.9086020675566275,
48.71211628317572
],
[
1.977029724641852,
48.69007709065282
],
[
1.9380268126907942,
48.663014310869556
],
[
1.9059004038856775,
48.68139940276142
],
[
1.9020902267645763,
48.638079149302555
],
[
1.8821344534680975,
48.62423252424017
],
[
1.9008723646838,
48.62423252424018
],
[
1.8853998352913024,
48.448315795534654
],
[
1.7548343829094222,
48.459936767662384
],
[
1.5848481682316446,
48.31986594114687
]
]
],
[
[
[
1.7796498887017833,
48.75364922492895
],
[
1.9059004038856775,
48.68139940276142
],
[
1.9086020675566275,
48.71211628317572
],
[
1.7796498887017833,
48.75364922492895
]
]
],
[
[
[
2.0474541685456376,
48.433892157002646
],
[
2.269137922503419,
48.414161204603545
],
[
2.3139242542554825,
48.62423252424017
],
[
2.14201346746852,
48.62423252424017
],
[
2.140165825025228,
48.54733551405033
],
[
2.1779387566694766,
48.52571906686143
],
[
2.139324407980982,
48.51231658749331
],
[
2.13897493841921,
48.497772017709025
],
[
2.0474541685456376,
48.433892157002646
]
]
],
[
[
[
2.268015568539596,
48.408896777510364
],
[
2.2741686461205703,
48.41371344527771
],
[
2.269137922503419,
48.414161204603545
],
[
2.268015568539596,
48.408896777510364
]
]
],
[
[
[
2.2741686461205703,
48.41371344527771
],
[
2.4578541878508133,
48.39736452202297
],
[
2.4938366712502784,
48.58567095470934
],
[
2.2741686461205703,
48.41371344527771
]
]
]
])
Apply turf.difference to subtract each hole from the world polygon;
let result = turf.difference(worldPolygon, multiPolygon);
The output from Turf.js v5.16 works as expected, but in Turf.js v6.5, the result is incorrect.
Expected Result:
The world polygon should have the specified holes subtracted correctly, and the resulting polygon should reflect these changes.
https://jsfiddle.net/om39s8fh/1/
Actual Result:
In Turf.js v6.5 and recent versions, the output is incorrect, and the holes do not seem to be subtracted from the world polygon as expected. https://jsfiddle.net/yg2dj108/2/
The issue described in this comment has a different cause and is being tracked here instead - https://github.com/Turfjs/turf/issues/2887
Hi @elyeshkiri and @hf-farmqa. Thanks for raising and for the examples. Between 5.16 and 6.5.0 and then 7+ Turf has switched polygon clipping libraries a couple of times to address various issues.
It's becoming apparent that this has just resulted in other issues (such as yours) coming to the fore. Will take a look.
Hi @hf-farmqa. Have confirmed your issue isn't the same as OPs. Could I please trouble you to log the behaviour as a separate issue? Better if you do it so you are subscribed, etc. Just copy pasting your comments above would be fine. Thank you 🙏