{"action":"created","issue":{"url":"https://api.github.com/repos/mapnik/mapnik/issues/3070","labels_url":"https://api.github.com/repos/mapnik/mapnik/issues/3070/labels{/name}","comments_url":"https://api.github.com/repos/mapnik/mapnik/issues/3070/comments","events_url":"https://api.github.com/repos/mapnik/mapnik/issues/3070/events","html_url":"https://github.com/mapnik/mapnik/issues/3070","id":106450981,"number":3070,"title":"Strange artifacts with line-offset and MultiLineString","user":{"login":"ericfischer","id":1951835,"avatar_url":"https://avatars.githubusercontent.com/u/1951835?v=3","gravatar_id":"","url":"https://api.github.com/users/ericfischer","html_url":"https://github.com/ericfischer","followers_url":"https://api.github.com/users/ericfischer/followers","following_url":"https://api.github.com/users/ericfischer/following{/other_user}","gists_url":"https://api.github.com/users/ericfischer/gists{/gist_id}","starred_url":"https://api.github.com/users/ericfischer/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/ericfischer/subscriptions","organizations_url":"https://api.github.com/users/ericfischer/orgs","repos_url":"https://api.github.com/users/ericfischer/repos","events_url":"https://api.github.com/users/ericfischer/events{/privacy}","received_events_url":"https://api.github.com/users/ericfischer/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":7,"created_at":"2015-09-15T00:06:55Z","updated_at":"2015-09-16T19:29:31Z","closed_at":null,"body":"Sorry for the Mapbox-centricity of this issue but I think it is a general problem. There are very strange artifacts when drawing MultiLineString features with line-offset.\r\n\r\nMake a tileset that combines many lines together into the same feature using moveto, lineto, moveto, lineto, etc. As an example, I used the TIGER 2014 streets for Alameda County, California (uploaded to Mapbox as `enf.4rcqh0k9`) and encoded with tippecanoe:\r\n\r\n    cat tl_2014_06001_roads.json | ./tippecanoe -f -X -aco -o multilinestring.mbtiles\r\n\r\nMake a style for it like this:\r\n\r\n    #multilinestring {\r\n      line-width: 2;\r\n      line-offset: 6;\r\n    }\r\n\r\nThere are many strange drawing artifacts as shown in this screenshot:\r\n\r\n![screen shot 2015-09-14 at 5 00 13 pm](https://cloud.githubusercontent.com/assets/1951835/9864773/45e0faa4-5b02-11e5-9311-21e82de9fa17.png)\r\n\r\nMany line segments do not draw at all. Others are drawn but with hooks on the ends, proportional to the size of the line-offset.\r\n\r\ncc @flippmoke @springmeyer @danpat "},"comment":{"url":"https://api.github.com/repos/mapnik/mapnik/issues/comments/140859476","html_url":"https://github.com/mapnik/mapnik/issues/3070#issuecomment-140859476","issue_url":"https://api.github.com/repos/mapnik/mapnik/issues/3070","id":140859476,"user":{"login":"ericfischer","id":1951835,"avatar_url":"https://avatars.githubusercontent.com/u/1951835?v=3","gravatar_id":"","url":"https://api.github.com/users/ericfischer","html_url":"https://github.com/ericfischer","followers_url":"https://api.github.com/users/ericfischer/followers","following_url":"https://api.github.com/users/ericfischer/following{/other_user}","gists_url":"https://api.github.com/users/ericfischer/gists{/gist_id}","starred_url":"https://api.github.com/users/ericfischer/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/ericfischer/subscriptions","organizations_url":"https://api.github.com/users/ericfischer/orgs","repos_url":"https://api.github.com/users/ericfischer/repos","events_url":"https://api.github.com/users/ericfischer/events{/privacy}","received_events_url":"https://api.github.com/users/ericfischer/received_events","type":"User","site_admin":false},"created_at":"2015-09-16T19:29:31Z","updated_at":"2015-09-16T19:29:31Z","body":"This screenshot is from version 0.2.7."}}