{"action":"created","issue":{"url":"https://api.github.com/repos/KhronosGroup/glTF/issues/1484","repository_url":"https://api.github.com/repos/KhronosGroup/glTF","labels_url":"https://api.github.com/repos/KhronosGroup/glTF/issues/1484/labels{/name}","comments_url":"https://api.github.com/repos/KhronosGroup/glTF/issues/1484/comments","events_url":"https://api.github.com/repos/KhronosGroup/glTF/issues/1484/events","html_url":"https://github.com/KhronosGroup/glTF/issues/1484","id":380460369,"node_id":"MDU6SXNzdWUzODA0NjAzNjk=","number":1484,"title":"Adobe Dimension glTF models","user":{"login":"emackey","id":1235080,"node_id":"MDQ6VXNlcjEyMzUwODA=","avatar_url":"https://avatars2.githubusercontent.com/u/1235080?v=4","gravatar_id":"","url":"https://api.github.com/users/emackey","html_url":"https://github.com/emackey","followers_url":"https://api.github.com/users/emackey/followers","following_url":"https://api.github.com/users/emackey/following{/other_user}","gists_url":"https://api.github.com/users/emackey/gists{/gist_id}","starred_url":"https://api.github.com/users/emackey/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/emackey/subscriptions","organizations_url":"https://api.github.com/users/emackey/orgs","repos_url":"https://api.github.com/users/emackey/repos","events_url":"https://api.github.com/users/emackey/events{/privacy}","received_events_url":"https://api.github.com/users/emackey/received_events","type":"User","site_admin":false},"labels":[{"id":1085697102,"node_id":"MDU6TGFiZWwxMDg1Njk3MTAy","url":"https://api.github.com/repos/KhronosGroup/glTF/labels/extension/KHR_draco_mesh_compression","name":"extension/KHR_draco_mesh_compression","color":"7fdadc","default":false}],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":1,"created_at":"2018-11-13T22:53:27Z","updated_at":"2018-11-14T17:44:33Z","closed_at":null,"author_association":"MEMBER","body":"Here's a test model that a coworker of mine exported from Adobe Dimension: [AGI_Coffee_Cup.zip](https://github.com/KhronosGroup/glTF/files/2578436/AGI_Coffee_Cup.zip)\r\n\r\nThis model uses Draco compression, and has two primitives (a cup and a lid).  There seem to be some \"dummy\" accessors at the top though, that contain a degenerate triangle at the origin, with zero size:\r\n\r\n```\r\n  \"accessors\": [\r\n    {\r\n      \"bufferView\": 0,\r\n      \"componentType\": 5126,\r\n      \"count\": 3,\r\n      \"type\": \"VEC3\",\r\n      \"max\": [\r\n        0,\r\n        0,\r\n        0\r\n      ],\r\n      \"min\": [\r\n        0,\r\n        0,\r\n        0\r\n      ]\r\n    },\r\n```\r\n\r\nThis renders fine in Babylon, but breaks in Cesium.  Cesium trusts the accessor min/max values, which are all zeros, and computes a zero-radius bounding sphere, and then decides that the primitives never need to render based on that radius.\r\n\r\nIs this a proper use of Draco?  Our official samples do something different with the accessors, and avoid the need for this dummy degenerate triangle outside of the Draco stream.  Is it OK for engines to rely on the accessor min/max information in Draco compressed models?\r\n\r\n/cc @MiiBond @lexaknyazev @FrankGalligan "},"comment":{"url":"https://api.github.com/repos/KhronosGroup/glTF/issues/comments/438753030","html_url":"https://github.com/KhronosGroup/glTF/issues/1484#issuecomment-438753030","issue_url":"https://api.github.com/repos/KhronosGroup/glTF/issues/1484","id":438753030,"node_id":"MDEyOklzc3VlQ29tbWVudDQzODc1MzAzMA==","user":{"login":"MiiBond","id":1069125,"node_id":"MDQ6VXNlcjEwNjkxMjU=","avatar_url":"https://avatars1.githubusercontent.com/u/1069125?v=4","gravatar_id":"","url":"https://api.github.com/users/MiiBond","html_url":"https://github.com/MiiBond","followers_url":"https://api.github.com/users/MiiBond/followers","following_url":"https://api.github.com/users/MiiBond/following{/other_user}","gists_url":"https://api.github.com/users/MiiBond/gists{/gist_id}","starred_url":"https://api.github.com/users/MiiBond/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/MiiBond/subscriptions","organizations_url":"https://api.github.com/users/MiiBond/orgs","repos_url":"https://api.github.com/users/MiiBond/repos","events_url":"https://api.github.com/users/MiiBond/events{/privacy}","received_events_url":"https://api.github.com/users/MiiBond/received_events","type":"User","site_admin":false},"created_at":"2018-11-14T17:44:33Z","updated_at":"2018-11-14T17:44:33Z","author_association":"CONTRIBUTOR","body":"Yes, this is known. I misread the spec and never noticed the mistake because the user can only get Draco compression when they use our \"publish\" feature. This takes the user to the Babylon viewer which displays the model correctly. We don't yet provide a download link for the glTF.\r\n\r\nI have a fix for this now so it'll be in the next prerelease of Dimension. www.adobeprerelease.com\r\n\r\nThanks."}}
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