{"action":"created","issue":{"url":"https://api.github.com/repos/tangrams/tangram-docs/issues/111","repository_url":"https://api.github.com/repos/tangrams/tangram-docs","labels_url":"https://api.github.com/repos/tangrams/tangram-docs/issues/111/labels{/name}","comments_url":"https://api.github.com/repos/tangrams/tangram-docs/issues/111/comments","events_url":"https://api.github.com/repos/tangrams/tangram-docs/issues/111/events","html_url":"https://github.com/tangrams/tangram-docs/issues/111","id":160283657,"number":111,"title":"whither `angle`?","user":{"login":"meetar","id":459970,"avatar_url":"https://avatars.githubusercontent.com/u/459970?v=3","gravatar_id":"","url":"https://api.github.com/users/meetar","html_url":"https://github.com/meetar","followers_url":"https://api.github.com/users/meetar/followers","following_url":"https://api.github.com/users/meetar/following{/other_user}","gists_url":"https://api.github.com/users/meetar/gists{/gist_id}","starred_url":"https://api.github.com/users/meetar/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/meetar/subscriptions","organizations_url":"https://api.github.com/users/meetar/orgs","repos_url":"https://api.github.com/users/meetar/repos","events_url":"https://api.github.com/users/meetar/events{/privacy}","received_events_url":"https://api.github.com/users/meetar/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/tangrams/tangram-docs/labels/question","name":"question","color":"cc317c"}],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":1,"created_at":"2016-06-14T21:04:52Z","updated_at":"2016-06-14T21:41:03Z","closed_at":null,"body":"Tangram JS supports an undocumented `angle` parameter when drawing `point` geometries, but ES currently doesn't – per https://github.com/tangrams/tangram-es/issues/551, has the fate of this feature been decided, either _de jure_ or _de facto_?\r\n\r\ncc @blair1618 "},"comment":{"url":"https://api.github.com/repos/tangrams/tangram-docs/issues/comments/226024794","html_url":"https://github.com/tangrams/tangram-docs/issues/111#issuecomment-226024794","issue_url":"https://api.github.com/repos/tangrams/tangram-docs/issues/111","id":226024794,"user":{"login":"blair1618","id":3371850,"avatar_url":"https://avatars.githubusercontent.com/u/3371850?v=3","gravatar_id":"","url":"https://api.github.com/users/blair1618","html_url":"https://github.com/blair1618","followers_url":"https://api.github.com/users/blair1618/followers","following_url":"https://api.github.com/users/blair1618/following{/other_user}","gists_url":"https://api.github.com/users/blair1618/gists{/gist_id}","starred_url":"https://api.github.com/users/blair1618/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/blair1618/subscriptions","organizations_url":"https://api.github.com/users/blair1618/orgs","repos_url":"https://api.github.com/users/blair1618/repos","events_url":"https://api.github.com/users/blair1618/events{/privacy}","received_events_url":"https://api.github.com/users/blair1618/received_events","type":"User","site_admin":false},"created_at":"2016-06-14T21:41:02Z","updated_at":"2016-06-14T21:41:02Z","body":"Right, so, to recap: the problem with a single parameter called \"angle\" is that it doesn't specify what coordinate system the angle refers to. Specifically, it's ambiguous whether the angle is relative to world space (the cardinal directions on the map) or screen space (the axes of your window), and there are circumstances where both are appropriate. \r\n\r\nThe best solution I can come up with is to add another parameter: a boolean flag that specifies whether the geometry should be treated as a \"billboard\" (which rotates in screen space) or a \"sticker\" (which rotates in world space). For example:\r\n\r\n```yaml\r\nicons:\r\n  sprite: location-gem\r\n  billboard: false\r\n  angle: global.bearing\r\n```\r\nwould create an icon rotated by the amount `global.bearing` in *world space* (units and signs of angles is a separate discussion), and\r\n\r\n```yaml\r\nicons:\r\n  sprite: train\r\n  billboard: true\r\n  angle: global.icon_tilt\r\n```\r\nwould create an icon rotated by the amount `global.icon_tilt` in *screen space*. "}}
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