2010/4/19 Václav Šmilauer <[email protected]> > > > > > Yes, I confirm (by myself :-) ) that doing so we account for the > > applied displacement twice. Actually this fact is already documented > > and avoid in JumpChangeSe3 class. Maybe we can add a comment also in > > TranslationEngine so that if one wants to use it on dynamic bodies, it > > knows that in such a way you apply the displacement (giving velocity > > as input) twice. > > Actually I do not see another way to apply TranslationEngine to > > dynamic bodies avoiding this problem. In fact, one could use > > JumpChangeSe3 on dynamic bodies as well, but not using ScGeom since it > > needs velocities. > > There is actually https://bugs.launchpad.net/yade/+bug/398089 which is > closely related. > > Reading JumpChangeSe3 (wouldn't it be better to call it StepChangeSe3, > or rather StepChange... something else?) code, positions are updated "by > hand" > > if(!setVelocities || (setVelocities && !b->isDynamic)) > > i.e. either (1st case) NewtonIntegrator will not update position because > velocity is zero, or (2nd case) NewtonIntegrator will not update > position because the body is not dynamic. > > TranslationEngine doesn't make this distinction, it wasn't really > (probably) conceived for such fine-grained control. >
I personally think this is a very basic task, so we should be able in Yade to run a simulation in displacement control (totally working, I mean). Any advice how to do that? Say that one simply wants to apply a displacement (fixed or whatever) at each time step being the bodies dynamic.. cheers, Chiara > > One could add a flag to JumpChangeSe3 so that the delta wouldn't mean > delta in one timestep, but in 1 second; that would make it functionally > superset of TranslationEngine actually. > > (I was also planning -- or I've written but never commited -- > interpolating engine between start and end position&orientation for a > particle....) > > Cheers, v. > > > > > _______________________________________________ > Mailing list: > https://launchpad.net/~yade-users<https://launchpad.net/%7Eyade-users> > Post to : [email protected] > Unsubscribe : > https://launchpad.net/~yade-users<https://launchpad.net/%7Eyade-users> > More help : https://help.launchpad.net/ListHelp >
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