Hi Anton, > Hi (Bruno?), > > it seems we are calculating distance between particles > for each interaction. Theoretically: no. It depends on the implementation of each Ig2, which is only supposed to return true or false. Practically: yes. Ig2's will usually compare distances all the time, in fact squared distances [1,2]. It is similar to LIGGGHT. [1] (pos2-pos1).squaredLength() < (rad1+rad2)^2 ? [2] https://github.com/yade/trunk/blob/master/pkg/dem/Ig2_Sphere_Sphere_ScGeom.cpp#L20
> It looks like relatively expensive > task. Note that there is no sqrt or division involved, at least. > Can we somehow skip this step No. Keeping virtual interactions to run the collider only each N steps has a price: we must check at each step if a virtual becomes real. > and call it > explicitly from contact law when we really need it? Not really. 1/ If [1] returns false, we skip Ip2 and Law2 completely. https://github.com/yade/trunk/blob/master/pkg/common/InteractionLoop.cpp#L110 Moving the same test to Law2 would need to run Ig2+Ip2+Law2 for all virtual interactions all the time, which would be a real waste when there are many of them. With large Verlet dist. virtual can be 80% of the total, and most of them will never reach the "Real" state. We better don't try to assign+run Ip2 and Law2 for those. 2/ If [1] returns true, the distance vector defined for the initial test is re-used for defining the normalized normal and the real distance. There is no wasted operations (again see [2]). A good implementation of a Law2 will not compute distance again: https://github.com/yade/trunk/blob/master/pkg/dem/ElasticContactLaw.cpp#L49 To me it seems nearly optimal. Cheers. Bruno _______________________________________________ Mailing list: https://launchpad.net/~yade-dev Post to : [email protected] Unsubscribe : https://launchpad.net/~yade-dev More help : https://help.launchpad.net/ListHelp
