[Bf-committers] some notes about new armatures

Ton Roosendaal ton at blender.org
Wed Oct 12 11:50:34 CEST 2005


I've just found one lagging bug, related to converting armatures to new  
armatures. It seems that some 2.38 saved files don't get a proper  
signal to create the DAG for poses.
If it happens, check if the problem goes away with a TAB-TAB command.


On 12 Oct, 2005, at 11:22, Ton Roosendaal wrote:

> Hi,
>> in MHO the refactoring of the animation system is really good,but  
>> there are some minor issues.
>> The new dag seems not to work correctly with constraint.I try a  
>> strechy arm setup for a rig and there is some lag (the same thing  
>> happens if I mix ipodrivers(great feature,thank you Ton) and python  
>> to control objects transformations.
> Python has not been 'dagged' yet fully, so that I cannot speak of. For  
> the rest, the Constraints and Drivers should all work without lag.
> For setting up correct and solvable dependencies, you have to keep  
> these rules in mind;
> 1- Cyclic dependencies are not solved at the moment. One reason is  
> because I know it can be often bypassed quite simple by artists, the  
> other is to really get a full understanding of what kind of (useful)  
> cyclic issues we need to solve.
> The current system is based on a very strict "calculate everything  
> only once" rule, which ensures a predictable cpu overhead (instead of  
> exponentially). I don't intend to sacrificy that, although on a  
> 'render' command, we could calculate everything twice to get rid of  
> lagging caused by cycles.
> 2- There are two DAG systems now, one for the Scene (object  
> relations), and one for each Pose (bone relations). The Scene DAG also  
> has all relations from Objects to Bones and viceversa.
> However, you cannot expect dependencies to work mixed then, meaning: a  
> Bone changes an Object, which changes a Bone in the same Pose again.  
> All relations within the entire Pose should fit in the Scene level  
> DAG.
> Further I am extremely interested in seeing good demo files (even when  
> very complex) of character rigs that have issues with lagging, that  
> way I can get a good reference suite to test further improvements  
> with.
> If you have lagging Poses, and they're not violating the above rules,  
> please post it in the bug tracker!
>> Another problem(in MHO a big problem)is the difference between  
>> rest pose and animation pose.The 2 things should be related in some  
>> way,I was able to replicate an ikhandle setup(speaking in maya  
>> therminology) with the follow path constraint,but the skinning is  
>> done in rest pose and there is no way to syncronize it( except  
>> manually)  with the animation constrainted pose,a function that can  
>> transform the rest pose into the pose created by  
>> the constraints could be very important for setups(I'm not a coder,I  
>> can't resolve the problem myself).
> Uuuh... I really don't understand this. It would help if you refer to  
> the article I wrote about Armatures/Pose though;
> http://www.blender.org/cms/How_Armatures_work.634.0.html
> The 'rest pose' doesn't really exist, it is the armature itself (what  
> you edit in editmode). All deformations - of course - are based on  
> changes with respect to this initial setup (that's what we call Pose).  
> There's no difference between "poses" or "animation poses", it's  
> really the same stuff.
>> Sorry if this is not the right place to speak about this,but it seems  
>> to me that really few people tries medium-advanced setup in blender  
>> and, as a consequence, some problems arising only in extreme  
>> situations cannot be found and analyzed.
> Reviewing current development is fine on this list. :) What we rather  
> not do here is endless discussions on feature requests, especially  
> when no developer is working on that.
> I also work almost daily with the animators in the Orange Studio,  
> they're very picky too, so you can bet they will kick me when I talk  
> nonsense. :P
> Thanks,
> -Ton-
> ----------------------------------------------------------------------- 
> ---
> Ton Roosendaal  Blender Foundation ton at blender.org  
> http://www.blender.org
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Ton Roosendaal  Blender Foundation ton at blender.org  

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