Hello Collada Friends,
I’d thought I’d try and fire up a discussion on roundtripping. To us, this is definitely one of the more attractive propositions of Collada. The idea that an artist could use multiple applications to compose a document, each application contributing to the document what it does best definitely sounds like heaven come to earth.
Unfortunately, using the tools I have available to me today, it seems heaven is still quite a distance from earth.
Let me describe some of the things I tried to do, and the outcomes. Maybe someone here can offer tips/tricks/pointers/advice on how to make things like this work. Or, perhaps we can get a good little discussion going on how these things could be made to work in the future.
Scenario one: What I tried first
Max 8, ColladaMax 1.06
- In Max, I created a cube. I then exported the scene to a Collada document.
- I opened the Collada document in a text editor, and added a couple of <extra> tags to various (legal, according to the spec) locations.
- I re-imported this document into Max.
- Without changing the document at all, I then exported it to a different Collada file.
–> Using diff showed the outcome of this; my extra tags were lost. They were not present in the newly exported document at all.
Scenario two: What I tried next
Maya 7, ColladaMaya 2.04, Max 8, ColladaMax 1.06
- In Maya, I set up a very basic scene with one Cube and one Plane.
- I set up some simple dynamics so the cube would fall and bounce off the plane.
- I exported this document to Collada.
- I imported the Collada document into Max.
–> Comically, the Y-UP/Z-UP demon struck and my scene was lying on it’s side.
–> Needless to say, there was no physics going on in my scene in Max, but I think this is to be expected.
- Then, I re-exported the document as a different Collada file
–> A simple diff between the original Maya exported document and the new Max exported document exposed that all my physics information had been lost! Ouch!
Scenario three: The extent of the lossage
Maya 7.0, ColladaMaya 2.04
- Take the simple Maya scene with dynamics. (nice cube bouncing off plane)
- Export it to Collada.
- Close and restart Maya.
- Import the Collada document.
–> Uh oh, it looks like my gravity field was lost somewhere, so there are no functioning dynamics in the scene at this point.
So, I’m left with the feeling that we’ve got quite a ways to go before Collada roundtripping is a useful reality.
Does anyone have any experiences that they can relate to this? Have you had more or less success roundtripping Collada documents anywhere, for any reason?
I’m not really all that interested in physics, but more in the state of roundtripping in general. If our software were to embrace Collada, and roundtrip documents correctly by importing them and adding our own custom tags before re-exporting them it seems like it might all be for not if the custom tags are all consumed (meaning not re-export) by the DCC software.
I believe the implementation on the DCC side would be difficult as a plugin. My Maya and Max plug-in experience is limited, but I think maintaining the Collada document upon import, and reconciling any changes made in order to correctly export would be massively difficult. (If possible at all) I’d love to hear Guillaume’s opinion on this as his experience dwarfs mine in this area.
Sorry that this post got kind of long, I look forward to your feedback/ideas.