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are there any good riggin books or resources that cover cycle errors?
1z1fbt2
K Mitchel
Nov 22, 2011
Post id: 309170 Report Item

cycle errors when they affect a joint.InverseMatrix/parentMatrix's attrs and so on in particular? When I run into these i do not know how to debug them and I'd like to spend some time

thank you

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Joojaa
Nov 23, 2011
Post id: 309172 Report Item

Tranforms known as DAG nodes can not cycle. DAG = Directed Acyclic Graph, acyclic means CAN NOT CYCLE. That means no message passing form child to parent, PERIOD! That is they are allways evalueted parent first, no amount of cycling does change that (parent evaluated before child so no changes in child has time to affect parent untill next evaluation).

Maya does not in general also cycle hence the warning. Its not a error, you can do it it just does not do whet most people assume hence the warning. That is the DG (yes, DG = Depencecy Graph) when evaluated only odes each node one time so a loop does not fire the nodes in loop in meaningful way. It is allowed however to do a cycle, and its can be useful.

>> ? When I run into these i do not know how to debug them

if you have one and dont know why then you did not indtend to have one so you delete it.

1z1fbt2
K Mitchel
Nov 27, 2011
Post id: 309197 Report Item

thanks 



only thing confusing to me now is~why cant all DG nodes be DAG nodes,  but the reverse is fine?

isn't the only acyclic trait about a DAG node in its parent/ hierarchal relationship ?

not the way its  attributes are connected?

 

you can create a cycle with connections

but thats not the cycle being prevented by a dag node  hierarchy right..? or am i off?

 

to be honest the cycle mostly seems fine, accept for the the connection below(pic)!


lol i am 70% sure i told maya to do that. accept maybe less now. it annoys me. 


just fyi the cycle's affecting a clavical set up for a "motion flow" rig. it has a switch to turn this auto clavical on/off (from auto shoulder w/clavical option, to simple shoulder  FK)

thing is since its got this clavical, there are two arm joint chains. 1 sits under the other and derives info for the  clavical movement. (joint chains are connected)

One of the arm joint chains is getting offset, and it doesn't act like a double transformation. welp i will keep messing with it, still if you know a good book or resource that covers dag and DG in depth lemme know


 



1g
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Joojaa
Nov 28, 2011
Post id: 309209 Report Item

>> only thing confusing to me now is~why cant all DG nodes be DAG nodes,  but the reverse is fine?

Its a definition thing, because every node in existence is a DG node. Its been decided by maya architects that way. DAG nodes exist because theres a specific need for passing sapce transforms in a 3d software, and the math behind transforms is noncumulative. Its a bit like goat cheese is a superset of cheese, not all cheese is made and needs to be made form goats milk

Remember maya does not show DAG connections as arrows in the dg mapping so its impossible for me to say because i cant see the outliner.

>> if you know a good book or resource that covers dag and DG in depth lemme know

read 4 books non of them was really helpful over whats in the manual. Thing is you can explained as to how it works. YOu need to understand the implications of that yourself.

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