[WF-General] Animation Blending

Erik Ogenvik erik at ogenvik.org
Wed Feb 29 12:06:39 PST 2012

I've pushed an alternative format to the animation_blend_masks_more_dynamic

Here you instead reference the bone groups per animation.
An example:

            <action name="__movement_walk" speed="1.000000">
                    <activation type="movement">walk</activation>
                    <activation type="movement">swim</activation>
                    <animation iterations="1">
                        <animationpart name="trns_walk" weight="1.000000">
                                <bonegroupref name="arms" />
            <bonegroup name="arms">
                    <bone index="1" />
                    <bone index="2" />
                    <bone index="3" />
                    <bone index="4" />


2012/2/27 Dean Bouvier <demarii.wf at gmail.com>

> Great, I'll build that branch locally and play around with it and then
> come to you with some working examples, and thoughts and we'll hash things
> out further.
> As for the variable weights... I can see a case for them but I think at
> this stage its not worth worrying about them, I'm really most interested in
> seeing the interaction between the states, and how well I can leverage the
> bonegroups as they are, come up with a sense of the workflow, where we want
> things to go and what future issues could arise so we can plan for them now.
> /Dean
> On Mon, Feb 27, 2012 at 6:56 AM, Erik Ogenvik <erik at ogenvik.org> wrote:
>> Hi, I've now added some code for this in the "animation_blend_mask"
>> branch of Ember. It's a bit experimental since I think we need some back
>> and forth until we've figured out how to do this the best way.
>> As it is now, you can add animation blend masks by adding a "bonegroups"
>> element after the "lights" element in the modeldef file.
>> Here's an example:
>>       <model>
>>       ...
>>       <lights />
>>           <bonegroups>
>>             <bonegroup name="arms">
>>                 <animations>
>>                     <animation>trns_walk</animation>
>>                 </animations>
>>                 <bones>
>>                     <bone index="1" />
>>                     <bone index="2" />
>>                     <bone index="3" />
>>                     <bone index="4" />
>>                 </bones>
>>             </bonegroup>
>>         </bonegroups>
>>       </model>
>> The "name" of the bonegroup has no bearing; it's just something to aid in
>> authoring etc.
>> When a blend mask is applied to an animation, it means that all of the
>> bones that are not in the blend mask get 0 weight, and those that are get 1
>> weight. We could of course add support for specifiying these numbers, but I
>> don't see any need of it. Tell me if it's needed.
>> One great change is that if a model has bonegroups, the animation blend
>> mode of the skeleton will be switched from "average" to "cumulative". This
>> can have some subtle effects if one's not careful.
>> /Erik
>> 2012/2/4 Dean Bouvier <demarii.wf at gmail.com>
>>> Ahh great I'm glad to hear that I was on the right track. That should
>>> work out really good actually as I should have a good base of default
>>> animations for use to test blending, using that method will definitely add
>>> some great versatility to things, I'm looking forward to it.
>>> On Thu, Feb 2, 2012 at 2:01 PM, Erik Ogenvik <erik at ogenvik.org> wrote:
>>>> Hi, using BlendMasks as described in those post sound like the right
>>>> way forward.
>>>> I also think your addition to the modeldefinition format is the correct
>>>> way for Ember. I'll whip up something, might take a week or two though.
>>>> /Erik
>>>> 2012/1/28 Dean Bouvier <demarii.wf at gmail.com>
>>>>> I did some initial tests using multiple Animations and even when I
>>>>> completely remove All Upper Body bones from one animation track and All leg
>>>>> bones from the other they are still somehow being averaged between the two
>>>>> tracks possibly against another default animation track or possible their
>>>>> initial orientation. This results in animations that are half of what they
>>>>> should be together. In the case of the arms they are out to the side like a
>>>>> big far man grabbing his belly after a big meal, and the legs only move at
>>>>> half their full range of motion.
>>>>> I did a little reading and I think what is needed is to use Blend
>>>>> Masks, and expose the Bone weights individually in some manner.  I'm not
>>>>> sure if the current blending system is using this Blend Mask method they
>>>>> are referring, perhaps it is the Averaging type rather then the
>>>>> Accumulative one. So I figured I would ask...
>>>>> See Forum post:
>>>>> http://www.ogre3d.org/forums/viewtopic.php?f=2&t=47798 in particular
>>>>> Kojak's post seems to give an example of how to use Blend Masks and the
>>>>> Accumulative method.
>>>>> Do you think we could apply this as an extension of the current XML
>>>>> system in use?
>>>>> Given that the current Exporter I am using doesn't exclude bones even
>>>>> when they don't have any keyframes this might solve the issue I have with
>>>>> having to hand edit all my skeleton files to remove unused bones from a
>>>>> track as well. But even with hand editing I'm unable to get a proper blend
>>>>> between Upper and Lower body animations.
>>>>> In my latest trials what I've been doing is splitting the Upper and
>>>>> Lower Body bones at the hips, and also planning to have Hands and the
>>>>> Head/Jaw, so basically I'm thinking of four main groups. Right now my focus
>>>>> is completely on the Upper and Lower body mixing, as these are the bones
>>>>> which are directly tied to MoCap data.
>>>>> Because of this, perhaps instead of having to apply 0 bone weight to
>>>>> each bone individually as Kojak suggested, it might be easier to create a
>>>>> set of bone groups, and then define what groups we expect to use from a
>>>>> track simply by use of a track naming convention, or by defining a group as
>>>>> part of the declaration....
>>>>> <animationpart name="trans_walk_arms" weight="1.000000" group="arms"/>
>>>>>   would be a simple example using both methods.
>>>>> and the arms group could be earlier defined in the modeldefinition
>>>>> like so...
>>>>>                     <bonegroup name="arms" >
>>>>>                         <bones>
>>>>>                             <bone index="23" />
>>>>>                             <bone index="24" />
>>>>>                             <bone index="25" />
>>>>>                             <bone index="26" />
>>>>>                             ...
>>>>>                         </bones>
>>>>>                     </bonegroup>
>>>>> The nice about this method is while I like the idea of breaking
>>>>> animation tracks into pieces as it could potentially lead to a much smaller
>>>>> overall skeleton file size, being able to use any animation and blend them
>>>>> and decide which bones of a track to weight on or off means even full body
>>>>> animations can potentially be used in piece with other animations to create
>>>>> something totally new.
>>>>> There is also a blend tree animation system which could be looked at
>>>>> as well.
>>>>> http://www.ogre3d.org/forums/viewtopic.php?f=11&t=45260
>>>>> What do you think Erik, any ideas on a clean way to approach this?
>>>>> Thanks,
>>>>> Dean
>>>>> On Wed, Jan 18, 2012 at 4:32 AM, Dean Bouvier <demarii.wf at gmail.com>wrote:
>>>>>> Great I'm glad to hear this will work, I'll definitely be looking
>>>>>> closely at things and defining all the tracks in such a way as to make the
>>>>>> best use out of such a system.
>>>>>> Thanks for the input.
>>>>>> Dean
>>>>>> On Tue, Jan 10, 2012 at 2:42 PM, Erik Ogenvik <erik at ogenvik.org>wrote:
>>>>>>> Hi, this sounds like an excellent approach.
>>>>>>> The current system is pretty basic, but what you describe isn't
>>>>>>> something that would be too hard to implement. It's mainly an issue of
>>>>>>> extending the current system. When doing these things I usually start with
>>>>>>> defining the data format (in xml), since everything flows from that. I can
>>>>>>> see if I can whip up an example.
>>>>>>> /Erik
>>>>>>> 2012/1/9 Dean Bouvier <demarii.wf at gmail.com>
>>>>>>>>  Hi Erik,
>>>>>>>> I've sent this to this general list so others can be aware of the
>>>>>>>> discussion and provide input if they desire, also cc'd Jayr too as I'm not
>>>>>>>> sure he watches the list anymore and his input would be welcome.
>>>>>>>> I have a few questions regarding the animations I'm working on for
>>>>>>>> the new standardized humanoid rig and my work schedule is alot less hectic
>>>>>>>> these days with only a few small jobs on the go so I plan to make use of it
>>>>>>>> by finishing this initial animation work I started on.
>>>>>>>> Since Ember supports Animation blending, I'm thinking that I should
>>>>>>>> consider breaking animation tracks into separate body parts so that these
>>>>>>>> can be blended to achieve a great range of motion. Let me give an example
>>>>>>>> based around kneeling.
>>>>>>>> Currently I have two forms of kneeling, one legged kneel like you
>>>>>>>> would see from a knight kneeling before his lord, or two legged kneeling
>>>>>>>> like that of a martial artist. Now some actions, which might be performed
>>>>>>>> from kneeling position, like digging in the ground with a trowel, working
>>>>>>>> something their hands, waving, speaking, looking around etc. all use bones
>>>>>>>> that are not directly tied to the legs. So it seems to me that if I were to
>>>>>>>> create 2 looping kneeling forms which only affect the leg, and then make
>>>>>>>> other animations which only deal with hands and arms, and then create a few
>>>>>>>> "one-shot" animations of getting down into these two kneeling positions,
>>>>>>>> and rise from them, and these should be able to blend together to achieve a
>>>>>>>> greater range of desired animations and lower the overall size of the
>>>>>>>> standard rig. It would simply require calling multiple tracks in the case
>>>>>>>> of selected game actions, like in the case of digging with a trowel a
>>>>>>>> kneeling action would be called, then a kneeling loop would play for the
>>>>>>>> duration and the digging action would be called and blended with it. Or the
>>>>>>>> case of a knight you would have him kneel to one leg, loop that one legged
>>>>>>>> kneel and then blend in fist to the chest animation.
>>>>>>>> This seems like a better approach to animating the characters then
>>>>>>>> creating a number of full body animations that perform all of the action
>>>>>>>> needed, as it will result in a smaller skeleton in memory, and also allow
>>>>>>>> world builders to define more variation in actions.
>>>>>>>> The one thing I was wondering about is whether it is possible to
>>>>>>>> delay some animations a set length of time so another animation can play
>>>>>>>> first, or maybe perform a "one-shot" animation before going into loop
>>>>>>>> animation(s). For instance in the kneeling example the process of going
>>>>>>>> from standing to kneeling does generally use all the body with the person
>>>>>>>> supporting their weight on one hand as they get down onto their knees, but
>>>>>>>> once there the arms could go to a default or neutral position and be
>>>>>>>> blended into and out of. Is it possible to do this sort of thing with the
>>>>>>>> current system somehow?
>>>>>>>> Do you have any ideas, thoughts, or questions regarding this idea?
>>>>>>>> I'm at the stage now where I have a fairly good range of motion
>>>>>>>> capture data for default actions, and a longer list of future data once I
>>>>>>>> get the defaults completed as you can see at:
>>>>>>>> https://docs.google.com/spreadsheet/ccc?key=0ArUzXoR0hnBzdGVzaGNjQkdvclg5Yy12UmlCWlRiOWc
>>>>>>>> Since I'm now at the stage of taking the BVh's into blender,
>>>>>>>> working on cleaning, and refining the data and saving them into action
>>>>>>>> strips to share with other modellers, now is the time to consider if
>>>>>>>> separating these further for blending is the best course of action. It
>>>>>>>> makes sense to me, but I wanted your opinion and direction on this matter,
>>>>>>>> especially since I'm not sure how or if the "one-shot" into looping
>>>>>>>> animations can be achieved, or whether blending multiple animations might
>>>>>>>> have other unforseen affects as opposed to just using full body animations
>>>>>>>> for game actions.
>>>>>>>> Thanks
>>>>>>>> Dean
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