## Re: [Algorithms] Animation and change of root

 Re: [Algorithms] Animation and change of root From: Jonathan Blow - 2004-11-09 18:56:52 ```Right, by disparaging the root I am saying that the hierarchy is not a=20 good idea. I have found that once we start doing things that are more interesting=20 than playing back animations, the hierarchy becomes vestigial and a big=20 hinderance. Sure, if you bend your elbow, your fingers move. But if=20 your hand hits a wall, it stops your elbow. Influence travels both=20 ways, that's what being in a physical reality is all about. Gribb, Gil wrote: >Well if you have a heirarchy, something has to be at the root. And the c= oncept of a heirarchy is not at all artifical. If I bend my elbow, my fin= gers move. But if I move my fingers, my elbow doesn't move. Quite a natur= al relation. > >-Gil > >-----Original Message----- >From: gdalgorithms-list-admin@... >[mailto:gdalgorithms-list-admin@...]On Behalf Of >Jonathan Blow >Sent: Tuesday, November 09, 2004 12:39 PM >To: gdalgorithms-list@... >Subject: Re: [Algorithms] Animation and change of root > > >"The root" of a skeleton is a pretty artificial concept that has mostly=20 >outlived its usefulness. Most people still do things that way, but it's= =20 >not a great idea. > >Dynamic re-rooting of a skeleton is pretty easy; the annoying part is=20 >when you have all this animation data that's stored bone-relative and=20 >you're like, hey, what do I do with all this stuff? The most=20 >straightforward thing is to evaluate that animation on a spare skeleton=20 >that has a fixed root, to get the object space transforms, then=20 >re-compute bone space transforms for the new hierarchy based on that.=20 >(If you like bone space, which a lot of people on this list seem to.) =20 >Anyway, that's not "fast" if you are thinking=20 >I-am-peephole-optimizing-my-algorithm fast, but it's O(n) with the=20 >number of bones, so hey, whatever. > >But if you have time to actively experiment on this stuff, I would=20 >explore doing things without a root. > > > >Chris Haarmeijer wrote: > > =20 > >>Hi, >> >>For an animation system, I have to change the root of the system freque= ntly >> =20 >> >>from the left foot to the right foot. Are there any publications availa= ble > =20 > >>on the subject of fast changing of the root of an animation hierarchy ? >> >>Kind regards, >> >>Chris Haarmeijer >>--- >>Keep IT Simple Software >>Van Alphenstraat 12 >>7514 DD Enschede >> >>W: http://www.keepitsimple.nl >>E: mailto:info@... >>T: +31 53 4356687 >> >> >> >>------------------------------------------------------- >>This SF.Net email is sponsored by: >>Sybase ASE Linux Express Edition - download now for FREE >>LinuxWorld Reader's Choice Award Winner for best database on Linux. >>http://ads.osdn.com/?ad_id=3D5588&alloc_id=3D12065&op=3Dclick >>_______________________________________________ >>GDAlgorithms-list mailing list >>GDAlgorithms-list@... >>https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list >>Archives: >>http://sourceforge.net/mailarchive/forum.php?forum_id=3D6188 >> >>=20 >> >> =20 >> > > > >------------------------------------------------------- >This SF.Net email is sponsored by: >Sybase ASE Linux Express Edition - download now for FREE >LinuxWorld Reader's Choice Award Winner for best database on Linux. >http://ads.osdn.com/?ad_id=3D5588&alloc_id=3D12065&op=3Dclick >_______________________________________________ >GDAlgorithms-list mailing list >GDAlgorithms-list@... >https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list >Archives: >http://sourceforge.net/mailarchive/forum.php?forum_id=3D6188 > > >------------------------------------------------------- >This SF.Net email is sponsored by: >Sybase ASE Linux Express Edition - download now for FREE >LinuxWorld Reader's Choice Award Winner for best database on Linux. >http://ads.osdn.com/?ad_idU88&alloc_id=12065&op=CCk >_______________________________________________ >GDAlgorithms-list mailing list >GDAlgorithms-list@... >https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list >Archives: >http://sourceforge.net/mailarchive/forum.php?forum_ida88 > > =20 > ```