{"action":"created","issue":{"url":"https://api.github.com/repos/CartoDB/mapnik/issues/34","repository_url":"https://api.github.com/repos/CartoDB/mapnik","labels_url":"https://api.github.com/repos/CartoDB/mapnik/issues/34/labels{/name}","comments_url":"https://api.github.com/repos/CartoDB/mapnik/issues/34/comments","events_url":"https://api.github.com/repos/CartoDB/mapnik/issues/34/events","html_url":"https://github.com/CartoDB/mapnik/pull/34","id":300709140,"number":34,"title":"V3.0.15 carto cache deviation","user":{"login":"Algunenano","id":664253,"avatar_url":"https://avatars2.githubusercontent.com/u/664253?v=4","gravatar_id":"","url":"https://api.github.com/users/Algunenano","html_url":"https://github.com/Algunenano","followers_url":"https://api.github.com/users/Algunenano/followers","following_url":"https://api.github.com/users/Algunenano/following{/other_user}","gists_url":"https://api.github.com/users/Algunenano/gists{/gist_id}","starred_url":"https://api.github.com/users/Algunenano/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Algunenano/subscriptions","organizations_url":"https://api.github.com/users/Algunenano/orgs","repos_url":"https://api.github.com/users/Algunenano/repos","events_url":"https://api.github.com/users/Algunenano/events{/privacy}","received_events_url":"https://api.github.com/users/Algunenano/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":{"login":"Algunenano","id":664253,"avatar_url":"https://avatars2.githubusercontent.com/u/664253?v=4","gravatar_id":"","url":"https://api.github.com/users/Algunenano","html_url":"https://github.com/Algunenano","followers_url":"https://api.github.com/users/Algunenano/followers","following_url":"https://api.github.com/users/Algunenano/following{/other_user}","gists_url":"https://api.github.com/users/Algunenano/gists{/gist_id}","starred_url":"https://api.github.com/users/Algunenano/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Algunenano/subscriptions","organizations_url":"https://api.github.com/users/Algunenano/orgs","repos_url":"https://api.github.com/users/Algunenano/repos","events_url":"https://api.github.com/users/Algunenano/events{/privacy}","received_events_url":"https://api.github.com/users/Algunenano/received_events","type":"User","site_admin":false},"assignees":[{"login":"Algunenano","id":664253,"avatar_url":"https://avatars2.githubusercontent.com/u/664253?v=4","gravatar_id":"","url":"https://api.github.com/users/Algunenano","html_url":"https://github.com/Algunenano","followers_url":"https://api.github.com/users/Algunenano/followers","following_url":"https://api.github.com/users/Algunenano/following{/other_user}","gists_url":"https://api.github.com/users/Algunenano/gists{/gist_id}","starred_url":"https://api.github.com/users/Algunenano/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Algunenano/subscriptions","organizations_url":"https://api.github.com/users/Algunenano/orgs","repos_url":"https://api.github.com/users/Algunenano/repos","events_url":"https://api.github.com/users/Algunenano/events{/privacy}","received_events_url":"https://api.github.com/users/Algunenano/received_events","type":"User","site_admin":false}],"milestone":null,"comments":6,"created_at":"2018-02-27T16:50:12Z","updated_at":"2018-03-01T10:43:36Z","closed_at":null,"author_association":"MEMBER","pull_request":{"url":"https://api.github.com/repos/CartoDB/mapnik/pulls/34","html_url":"https://github.com/CartoDB/mapnik/pull/34","diff_url":"https://github.com/CartoDB/mapnik/pull/34.diff","patch_url":"https://github.com/CartoDB/mapnik/pull/34.patch"},"body":"After the tests in https://github.com/CartoDB/Windshaft/pull/599 I noticed that in some cases the points moved around by a noticeable margin.\r\n\r\nI've seen 2 minimal issues (both affecting in a subpixel level, so yeah, not like they are easily seen):\r\n- `snap_to_pixels` wasn't being used when generating the cache images  (fill and stroke). Activating it when requested gives results more consistent with the previous behaviour.\r\n- The translation matrices were losing some precision due to using floor on top of floor doubles. I've changed it to reduce the number of floor calls which gives better subpixel precision.\r\n\r\nThese changes shouldn't impact performance."},"comment":{"url":"https://api.github.com/repos/CartoDB/mapnik/issues/comments/369552221","html_url":"https://github.com/CartoDB/mapnik/pull/34#issuecomment-369552221","issue_url":"https://api.github.com/repos/CartoDB/mapnik/issues/34","id":369552221,"user":{"login":"Algunenano","id":664253,"avatar_url":"https://avatars2.githubusercontent.com/u/664253?v=4","gravatar_id":"","url":"https://api.github.com/users/Algunenano","html_url":"https://github.com/Algunenano","followers_url":"https://api.github.com/users/Algunenano/followers","following_url":"https://api.github.com/users/Algunenano/following{/other_user}","gists_url":"https://api.github.com/users/Algunenano/gists{/gist_id}","starred_url":"https://api.github.com/users/Algunenano/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Algunenano/subscriptions","organizations_url":"https://api.github.com/users/Algunenano/orgs","repos_url":"https://api.github.com/users/Algunenano/repos","events_url":"https://api.github.com/users/Algunenano/events{/privacy}","received_events_url":"https://api.github.com/users/Algunenano/received_events","type":"User","site_admin":false},"created_at":"2018-03-01T10:43:35Z","updated_at":"2018-03-01T10:43:35Z","author_association":"MEMBER","body":"After testing it appears that it is the double add/substraction. I literally have no idea how, so I'll be testing each of the changes done in that commit individually."}}
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