{"action":"created","issue":{"url":"https://api.github.com/repos/RobotLocomotion/drake/issues/3325","repository_url":"https://api.github.com/repos/RobotLocomotion/drake","labels_url":"https://api.github.com/repos/RobotLocomotion/drake/issues/3325/labels{/name}","comments_url":"https://api.github.com/repos/RobotLocomotion/drake/issues/3325/comments","events_url":"https://api.github.com/repos/RobotLocomotion/drake/issues/3325/events","html_url":"https://github.com/RobotLocomotion/drake/issues/3325","id":174531541,"number":3325,"title":"Output KinematicsCache from RBP","user":{"login":"amcastro-tri","id":17601461,"avatar_url":"https://avatars.githubusercontent.com/u/17601461?v=3","gravatar_id":"","url":"https://api.github.com/users/amcastro-tri","html_url":"https://github.com/amcastro-tri","followers_url":"https://api.github.com/users/amcastro-tri/followers","following_url":"https://api.github.com/users/amcastro-tri/following{/other_user}","gists_url":"https://api.github.com/users/amcastro-tri/gists{/gist_id}","starred_url":"https://api.github.com/users/amcastro-tri/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/amcastro-tri/subscriptions","organizations_url":"https://api.github.com/users/amcastro-tri/orgs","repos_url":"https://api.github.com/users/amcastro-tri/repos","events_url":"https://api.github.com/users/amcastro-tri/events{/privacy}","received_events_url":"https://api.github.com/users/amcastro-tri/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/RobotLocomotion/drake/labels/priority:%20high","name":"priority: high","color":"b60205"},{"url":"https://api.github.com/repos/RobotLocomotion/drake/labels/team:%20dynamics","name":"team: dynamics","color":"0052cc"}],"state":"open","locked":false,"assignee":{"login":"amcastro-tri","id":17601461,"avatar_url":"https://avatars.githubusercontent.com/u/17601461?v=3","gravatar_id":"","url":"https://api.github.com/users/amcastro-tri","html_url":"https://github.com/amcastro-tri","followers_url":"https://api.github.com/users/amcastro-tri/followers","following_url":"https://api.github.com/users/amcastro-tri/following{/other_user}","gists_url":"https://api.github.com/users/amcastro-tri/gists{/gist_id}","starred_url":"https://api.github.com/users/amcastro-tri/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/amcastro-tri/subscriptions","organizations_url":"https://api.github.com/users/amcastro-tri/orgs","repos_url":"https://api.github.com/users/amcastro-tri/repos","events_url":"https://api.github.com/users/amcastro-tri/events{/privacy}","received_events_url":"https://api.github.com/users/amcastro-tri/received_events","type":"User","site_admin":false},"assignees":[{"login":"amcastro-tri","id":17601461,"avatar_url":"https://avatars.githubusercontent.com/u/17601461?v=3","gravatar_id":"","url":"https://api.github.com/users/amcastro-tri","html_url":"https://github.com/amcastro-tri","followers_url":"https://api.github.com/users/amcastro-tri/followers","following_url":"https://api.github.com/users/amcastro-tri/following{/other_user}","gists_url":"https://api.github.com/users/amcastro-tri/gists{/gist_id}","starred_url":"https://api.github.com/users/amcastro-tri/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/amcastro-tri/subscriptions","organizations_url":"https://api.github.com/users/amcastro-tri/orgs","repos_url":"https://api.github.com/users/amcastro-tri/repos","events_url":"https://api.github.com/users/amcastro-tri/events{/privacy}","received_events_url":"https://api.github.com/users/amcastro-tri/received_events","type":"User","site_admin":false}],"milestone":{"url":"https://api.github.com/repos/RobotLocomotion/drake/milestones/2","html_url":"https://github.com/RobotLocomotion/drake/milestones/C++%20simulator%20for%20Valkyrie","labels_url":"https://api.github.com/repos/RobotLocomotion/drake/milestones/2/labels","id":1488183,"number":2,"title":"C++ simulator for Valkyrie","description":null,"creator":{"login":"RussTedrake","id":6442292,"avatar_url":"https://avatars.githubusercontent.com/u/6442292?v=3","gravatar_id":"","url":"https://api.github.com/users/RussTedrake","html_url":"https://github.com/RussTedrake","followers_url":"https://api.github.com/users/RussTedrake/followers","following_url":"https://api.github.com/users/RussTedrake/following{/other_user}","gists_url":"https://api.github.com/users/RussTedrake/gists{/gist_id}","starred_url":"https://api.github.com/users/RussTedrake/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/RussTedrake/subscriptions","organizations_url":"https://api.github.com/users/RussTedrake/orgs","repos_url":"https://api.github.com/users/RussTedrake/repos","events_url":"https://api.github.com/users/RussTedrake/events{/privacy}","received_events_url":"https://api.github.com/users/RussTedrake/received_events","type":"User","site_admin":false},"open_issues":9,"closed_issues":1,"state":"open","created_at":"2016-01-06T19:28:11Z","updated_at":"2016-09-13T00:40:11Z","due_on":null,"closed_at":null},"comments":70,"created_at":"2016-09-01T14:01:26Z","updated_at":"2016-09-13T21:10:20Z","closed_at":null,"body":"Per discussion in #3316, we need to output the `KinematicsCache` as an output for `BotVisualizer` not having to recomputed already available quantities in the `KinematicsCache`.\r\nThe output will be in the form of an `AbstractValue` and `BotVisualizer` will have an input port for it.\r\n\r\nFor systems like a simple pendulum dynamics but that we want to render as a three dimensional multibody system, we will just leave the `KinematicsCache` port unconnected case in which the `BotVisualizer` will just instantiate its own `KinematicsCache` as it is done right now. Therefore we would need the capability to leave inputs unconnected and for `System<T>`'s to query whether these are connected or not.\r\n\r\nTwo questions arise @david-german-tri and @sherm1:\r\n\r\n1. Can we leave input ports disconnected? would it be a good idea to do so?\r\n2. Could we (should we?) provide a `System<T>` method to check whether an input port is connected or not? like `System<T>::is_input_port_conneted(port_number)`.\r\n\r\n"},"comment":{"url":"https://api.github.com/repos/RobotLocomotion/drake/issues/comments/246825550","html_url":"https://github.com/RobotLocomotion/drake/issues/3325#issuecomment-246825550","issue_url":"https://api.github.com/repos/RobotLocomotion/drake/issues/3325","id":246825550,"user":{"login":"tkoolen","id":2585880,"avatar_url":"https://avatars.githubusercontent.com/u/2585880?v=3","gravatar_id":"","url":"https://api.github.com/users/tkoolen","html_url":"https://github.com/tkoolen","followers_url":"https://api.github.com/users/tkoolen/followers","following_url":"https://api.github.com/users/tkoolen/following{/other_user}","gists_url":"https://api.github.com/users/tkoolen/gists{/gist_id}","starred_url":"https://api.github.com/users/tkoolen/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/tkoolen/subscriptions","organizations_url":"https://api.github.com/users/tkoolen/orgs","repos_url":"https://api.github.com/users/tkoolen/repos","events_url":"https://api.github.com/users/tkoolen/events{/privacy}","received_events_url":"https://api.github.com/users/tkoolen/received_events","type":"User","site_admin":false},"created_at":"2016-09-13T21:10:20Z","updated_at":"2016-09-13T21:10:20Z","body":"The controversial thing is sharing cache that is supposed to be **private to a subsystem** implicitly (i.e., not through output ports) with other subsystems in a diagram (e.g., https://github.com/RobotLocomotion/drake/issues/3325#issuecomment-245105482).\r\n\r\nThe proposal here is to associate cache **with the output of a subsystem**, not with the subsystem itself, so that it passes through an output port, and the dependencies are explicit.\r\n\r\nMaybe I completely misunderstood, but I was under the impression that the current cache design only associates cache with a subsystem."}}
{"actor":{"display_login":"tkoolen"}}