Khronos Public Bugzilla
Bug 57 - Hierarchical animation
Hierarchical animation
Status: REOPENED
Product: COLLADA
Classification: Unclassified
Component: Specification
1.4.1
All All
: P3 minor
: ---
Assigned To: Fabrice Robinet
COLLADA Work Group email alias
https://collada.org/public_forum/view...
:
Depends on:
Blocks:
  Show dependency treegraph
 
Reported: 2008-01-14 04:23 PST by bene
Modified: 2014-01-07 10:23 PST (History)
1 user (show)

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Description bene 2008-01-14 04:23:21 PST
In the specs, on <animation> there is a bound of sampler and channel.

A channel is always preceded by a sampler. On the <channel> page there is an example referencing samplers, but there are none.

This is unclear. Since channels and sampler are referencing why is there the limitation of a sequence: input(s), channel(s), sampler ?
Comment 1 bene 2008-01-14 05:34:11 PST
I missed that:

Looking at the example in the specs of <animation>, why is it not possible to instanciate an animation within an animation?

See Bug 58 for the absolute time problem. I think the animation tree does not benefit from the efficient COLLADA reference scheme.

Of course it makes sense if we consider an animation valid only for the current scene. This will mostly be the case for object-to-worldspace-transformation-animations. But animations should be limited to this. Many applications like the library approach and create a way of templating.
Comment 2 Mark Barnes 2008-03-10 01:47:47 PDT
The examples in the spec are not always complete and often just focus on showing the syntax of the current element under discussion. I will take this as a more general request for better (valid) examples per section, and for <animation> in particular.

The design of the schema in general is to have a strongly type schema that can validate .dae instance documents to a high degree. More is better and unbounded choices are only used when required (e.g. node transform stack). This approach is contrasted with the desire to enable rapid prototyping(empty document quotient) with optional elements and attributes.

The design of animation to-date does not include the next steps of defining a system of animation blending, media time-line, etc.. as you are noticing.

Assigned. Ellen do we already have better animation examples?
Comment 3 Ellen Finch 2008-03-10 21:12:02 PDT
The current working draft still has the same examples as in the 1.4.1 spec. We can make them more valid.
Comment 4 Ellen Finch 2008-06-10 13:00:24 PDT
Fixed in 1.5.0 specification.
Comment 5 Ellen Finch 2009-04-09 21:45:37 PDT
In 1.5.0, expanded syntax of examples in <animation>, but example in <channel>, reference by original description, still needs at least one <sampler> added.

For example, (the possible added line indicated with **):

<animation> 
  <sampler><input semantic="..." source="..."></sampler>
  <channel source="#Box-Translate-X-Sampler" target="Box/Trans.X"/> 
  <channel source="#Box-Translate-Y-Sampler" target="Box/Trans.Y"/> 
  <channel source="#Box-Translate-Z-Sampler" target="Box/Trans.Z"/> 
</animation> 

(See also Bug 126 for related question.)
Comment 6 Mark Barnes 2010-05-17 05:00:26 PDT
The animation element describes unique animations. The animation clip composites animations and can use instantiation.