N bone ik solver in ice

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anhungxadieu
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N bone ik solver in ice

Post by anhungxadieu » 15 May 2015, 10:54

Can we create n bone ik solver in ice or at least 3 bone ik solver? i already check this in ice kinematic workgroup but it still does'n work well, so i want to create my own version, i already do it with 2 bone.

Thank for any idea

This is my biped use ice rig for all element

Last edited by anhungxadieu on 16 May 2015, 05:34, edited 1 time in total.

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Mathaeus
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Re: N bone ik solver in ice

Post by Mathaeus » 15 May 2015, 13:04

I think you already know, that 3 or more involves a quite different method than 2. By nature of problem, for 2 elements, there is only one result, defined by law of cosines. For 3 or more, there's infinite number of results, so solver has to rely on additional, arbitrary parameter, like preferred rotation angle in SI "standard" kinematics chain - and this solver, afaik, performs a number of iterations in order to find the proper result. Don't know what is used in these ICE 3 or 4 bone IK chains - but, if these aren't enough good for you, I'm afraid it won't be easy to build a custom solution. 'Iterative', applied to non simulated ICE, means 'repeat' node, so, it won't be so fast, in best case.
Maybe it's possible to find some creative workaround against iterations, but can't imagine how to do that, for now.
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Pooby
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Re: N bone ik solver in ice

Post by Pooby » 15 May 2015, 14:11

But its only iterating on a tiny bit of data, not something like a massive million particle fluid sim.

IMO I wouldnt let the repeat node put you off. I use it all the time on rigs and notice no slowdown.

anhungxadieu
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Re: N bone ik solver in ice

Post by anhungxadieu » 15 May 2015, 16:04

i just need 3 bone ik for now but i don't know how to do it in 3 bone ik by use law of cosine

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Mathaeus
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Re: N bone ik solver in ice

Post by Mathaeus » 15 May 2015, 20:25

From what I gathered from internet, actually it seems that these ICE 3 bone and 4 bone solvers, are based on 'creativity', not on something iterative. Probably two or three 2 bone chains, somehow joined together - as docs are talking about ability to have a partial, per bone IK/FK blend. So, perhaps the best example for building your own, could be one of these two in factory examples.
About iterative solution and ICE repeat node, I really would not running into in - advance conclusions when it comes to n - element IK solvers, especially not when it comes to Softimaaaage thing..... *If* I'm correct, it's 'forth - back' iterative, sort of small simulation inside the solver. System like ICE is not suitable for something like this, simply as that.
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anhungxadieu
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Re: N bone ik solver in ice

Post by anhungxadieu » 16 May 2015, 05:15

Thank Mathaeus, i will take a look to factory compound again to find solution for this, but it quite difficult for me to understand what happen in this :(
Last edited by anhungxadieu on 16 May 2015, 05:33, edited 1 time in total.

anhungxadieu
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Re: N bone ik solver in ice

Post by anhungxadieu » 16 May 2015, 05:32

Hi Mathaeus, can u take a look on my scene, that i already have here this is 3 bone ik i want to achieve but still have a little problem
softimage 2015 sp1
http://ppl.ug/FYIG87wXtSY/

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Mathaeus
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Re: N bone ik solver in ice

Post by Mathaeus » 16 May 2015, 14:51

Unfortunately I can't load this, don't have SI 2015. Anyway here's small explanation, how I'd imagine 'combined' 3 bone chain. Base is big, blue chain, yellow chain is just attached to second bone of blue one. Red is what we will use for final output.
In order to do something meaningful, second bone of blue chain has to gradually change its length, according to distance between root and effector. Longer distance between root and effector = longer length of second, lighter blue bone. (Or, maybe it's smoother to change the length of both, so root of yellow chain become attached to something that just follows the orientation of first blue bone). Tricky part is to get the proper factor, how light blue bone ( or both blue bones) changes its length. If you can get ICE variance of Andy Nicholas Soft IK solution, this should be the best option. If not, there's screenshot of one Soft IK I've made for something else. Of course, even you won't be using stretchy bones, probably you'll want to use math, used in Soft IK thing.

Image
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anhungxadieu
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Re: N bone ik solver in ice

Post by anhungxadieu » 16 May 2015, 15:26

thank you very much! Mathaeus :)

i get your idea i will do some test and post it in here :)

anhungxadieu
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Re: N bone ik solver in ice

Post by anhungxadieu » 18 May 2015, 18:47

hi,

i finish that one thank Mathaeus for a idea :)