Re: [Xvrml-agents] on animation

[Miriam E. <mi...@we...>]

Hi Jeff and everybody,

Jeff Sonstein wrote:
> On Jun 27, 2005, at 8:18 PM, Miriam English wrote:

>> Currently, in vrml and xvrml there are some fairly arcane animation  
>> capabilities (all the interpolator nodes)
> 
> this is indeed the next thing in the Project work-plan:
> revise the interpolators

My suggestion is to leave the interpolators so pre-existing work isn't broken (perhaps make its inclusion in viewers optional), but add simpler, more sensible stuff.


>> The only sensible way achieve simple, flexible animations is the  use 
>> a different, simpler kind of
>> movement: a move command consisting of a force operating upon an  
>> object's mass.
> 
> so the idea is to simplify the animation declaration in the xVRML code
> and leave more of the how-to-act to the implementation
> [and thus to be spelled out in spec text]
> ??

I'm not sure how to do it in xvrml, but in classic style vrml it could be something like:

Force {
	intensity 0.0
	angle 0.0 0.0 0.0  0.0
	at 0.0 0.0 0.0
	children [
		Group {
			...
		}
	]
}

The force would be a grouping node and its scope would only cover the objects it groups. This would let the author create things like wind or alternative gravities, etc.  The intensity is how hard the force pushes (or pulls if it is negative) and the angle is the direction that the force pushes (or pulls). The at attribute is optional and lets the author focus the action of the force onto a particular point of the object affected by the force (lets you turn an object by pushing it off-center, for instance).

This is just off the top of my head. Somebody else might think of a better way.
I actually hate the children[] attribute so my own choice would not include that, but I displayed it this way for the sake of familiar ground.


> so any given geometry node may have an optional mass attribute set
> and will have a default mass value??

Yes. I'd favor adding a mass node or attribute to all geometries.

It may be that more such qualities need adding later too, so an open mind needs to be kept on the best way to do this. Other qualities that might be useful to have one day could be: elasticity, hardness, tensileStrength, compressiveStrength, viscosity, translucent, conductHeat, conductElectric, magnetic, ferrous, grain...


>> its mass and the IK links to lower- and upper-arm.
> 
> ahhhhhh
> there is the "kicker"...
> how to deal with inverse-kinesmatics links
> and their complexity

I'm 99% certain ODE handles IK itself. This simplifies the viewer incredibly.
I should look again just to make absolutely sure.

Best wishes,

	- Miriam


-- 
---------=---------=---------=---------=---------=---------=------
A life! Cool! Where can I download one of those from?
---------=---------=---------=---------=---------=---------=------
http://werple.net.au/~miriam
My live Journal page http://www.livejournal.com/users/miriam_e/