Jan Ciger wrote: > [...] > To conclude this discussion on IK - if someone knows how to program in > C++ and wants to play with IK, have a look at HMS IKAN library: > http://cg.cis.upenn.edu/hms/software/ikan/ikan.html > > It allows up to three joints (I think) to be simulated, e.g. an arm or > leg. We have used this library for initial development, it does work, > but you will quickly see the problems I was talking about in my previous > e-mails.
The viewer already uses IK in such a simplified case in order to keep avatar's feet flush with uneven ground or other surfaces. The implementation is quite complicated and therefore buggy and and sometimes funny looking but the results are *much* better than not doing it. So far as I know, it's not terribly computationally expensive, so the question in my mind is what would be the next most valuable situation we could apply it to? Any really big overhauls are unlikely to ever happen, so what should be the next baby step? Personally I would love to see avatar hand-holding implemented but involving multiple avatars may already be too big of a step for such a proof-of-concept. Argent says that he's already done something along these lines and I would love to see the results. I like his approach of only attempting to make the minor adjustments needed to make things fit. I will offer one possible refinement to his suggestion of only attempting IK adjustments when the miss is small: I suspect that we'll want to smooth over the discontinuity between attempting and not attempting IK. I think it might be good to have three zones. Within short error distances, do as he suggests; within a somewhat larger error, use IK to get as close as possible even though it misses; and at further distances, don't invoke IK at all. For example, this would allow you to ride a motorcycle while keeping your hands on the handlebars, but when you get bumped briefly too far, you'll continue reaching for them, and when you get bumped too far, you'll give up trying to maintain your grip. It will therefore look natural when you eventually reattach to the handlebars. I expect that whatever we attempt in this way should probably involve the existing feet-to-ground code, either extending or replacing it. -Melinda _______________________________________________ Policies and (un)subscribe information available here: http://wiki.secondlife.com/wiki/SLDev Please read the policies before posting to keep unmoderated posting privileges
