{"action":"created","issue":{"url":"https://api.github.com/repos/AnalyticalGraphicsInc/3d-tiles/issues/141","repository_url":"https://api.github.com/repos/AnalyticalGraphicsInc/3d-tiles","labels_url":"https://api.github.com/repos/AnalyticalGraphicsInc/3d-tiles/issues/141/labels{/name}","comments_url":"https://api.github.com/repos/AnalyticalGraphicsInc/3d-tiles/issues/141/comments","events_url":"https://api.github.com/repos/AnalyticalGraphicsInc/3d-tiles/issues/141/events","html_url":"https://github.com/AnalyticalGraphicsInc/3d-tiles/issues/141","id":186056166,"number":141,"title":"Adding Batch IDs to GLTFs Via COLLADA Models","user":{"login":"KermMartian","id":1566659,"avatar_url":"https://avatars.githubusercontent.com/u/1566659?v=3","gravatar_id":"","url":"https://api.github.com/users/KermMartian","html_url":"https://github.com/KermMartian","followers_url":"https://api.github.com/users/KermMartian/followers","following_url":"https://api.github.com/users/KermMartian/following{/other_user}","gists_url":"https://api.github.com/users/KermMartian/gists{/gist_id}","starred_url":"https://api.github.com/users/KermMartian/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/KermMartian/subscriptions","organizations_url":"https://api.github.com/users/KermMartian/orgs","repos_url":"https://api.github.com/users/KermMartian/repos","events_url":"https://api.github.com/users/KermMartian/events{/privacy}","received_events_url":"https://api.github.com/users/KermMartian/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":1,"created_at":"2016-10-29T03:15:00Z","updated_at":"2016-10-29T04:12:28Z","closed_at":null,"body":"My colleague @elfprince13 has been working on adding COLLADA to b3dm generation to a toolchain of ours, and we've encountered some confusion between the content of AnalyticalGraphicsInc/3d-tiles/TileFormats/Batched3DModel/README.md and COLLADA2glTF. Specifically, \"The batchId is identified by the glTF technique parameter semantic BATCHID.\" We believe this means that we'll need an `input` tag in our COLLADA `triangles` tags (eg, `<input offset=\"2\" source=\"#batch1-batchid\" semantic=\"BATCHID\"/>`), and we'll also need COLLADA2glTF to add an entry for `batchid` with semantic `BATCHID` in the parameters section of its techniques -> technique entries. Are you familiar with a version of COLLADA2glTF that already knows about `batchid`/`BATCHID`? If we fork KhronosGroup/glTF/ and implement it ourselves, where might I find the corresponding 5-digit type ID for it?\r\n\r\nAs a second point of confusion, we note \"each vertex has an unsigned short batchId attribute [...]\", but \"In the vertex shader, the attribute is named a_batchId and is declared as: `attribute float a_batchId;`\". Is the mismatch between unsigned short and float an intentional one?\r\n\r\nThanks in advance for your help, and hopefully this discussion will drive an eventual PR to clarify that documentation."},"comment":{"url":"https://api.github.com/repos/AnalyticalGraphicsInc/3d-tiles/issues/comments/257069721","html_url":"https://github.com/AnalyticalGraphicsInc/3d-tiles/issues/141#issuecomment-257069721","issue_url":"https://api.github.com/repos/AnalyticalGraphicsInc/3d-tiles/issues/141","id":257069721,"user":{"login":"lilleyse","id":915398,"avatar_url":"https://avatars.githubusercontent.com/u/915398?v=3","gravatar_id":"","url":"https://api.github.com/users/lilleyse","html_url":"https://github.com/lilleyse","followers_url":"https://api.github.com/users/lilleyse/followers","following_url":"https://api.github.com/users/lilleyse/following{/other_user}","gists_url":"https://api.github.com/users/lilleyse/gists{/gist_id}","starred_url":"https://api.github.com/users/lilleyse/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/lilleyse/subscriptions","organizations_url":"https://api.github.com/users/lilleyse/orgs","repos_url":"https://api.github.com/users/lilleyse/repos","events_url":"https://api.github.com/users/lilleyse/events{/privacy}","received_events_url":"https://api.github.com/users/lilleyse/received_events","type":"User","site_admin":false},"created_at":"2016-10-29T04:12:28Z","updated_at":"2016-10-29T04:12:28Z","body":"Yeah you have the right idea for editing a COLLADA model with batch ids.\r\n\r\n> Are you familiar with a version of COLLADA2glTF that already knows about batchid/BATCHID\r\n\r\nWe have some internal tools for this but I haven't seen anything public that handles BATCHID. I guess anywhere you see the other semantics you would also need to handle the `BATCHID` semantic. I'm not sure what you mean by a 5-digit ID, are you referring to the technique's parameter type?\r\n\r\n> Is the mismatch between unsigned short and float an intentional one?\r\n\r\nSort of... WebGL1 doesn't support integer attributes. All vertex attributes are ultimately treated as floats in the shader. Technically the batch id attribute could be any type so maybe the spec should be more lenient in that area."}}
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