atom feed95 messages in org.blender.bf-committersRe: [Bf-committers] Collada importer/...
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Juan LinietskyJan 9, 2012 6:07 am 
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Domino MaramaJan 9, 2012 7:53 am 
spatialJan 9, 2012 2:52 pm 
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Antony RiakiotakisJan 9, 2012 3:33 pm 
Campbell BartonJan 9, 2012 3:37 pm 
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Ton RoosendaalJan 10, 2012 2:15 am 
johannes amorosaJan 10, 2012 3:29 am 
spatialJan 10, 2012 3:57 am 
François T.Jan 10, 2012 5:57 am 
Erwin CoumansJan 10, 2012 6:30 am 
Gaia ClaryJan 10, 2012 7:46 am 
Juan LinietskyJan 10, 2012 1:47 pm 
Daniel Salazar - 3Developer.comJan 10, 2012 1:53 pm 
Juan LinietskyJan 10, 2012 2:39 pm 
Ton RoosendaalJan 11, 2012 2:06 am 
SebastianJan 11, 2012 12:00 pm 
Juan LinietskyJan 11, 2012 7:27 pm 
Juha Mäki-KantoJan 14, 2012 12:27 pm 
Juha Mäki-KantoJan 15, 2012 3:21 am 
Juan LinietskyJan 15, 2012 6:10 am 
SebastianJan 15, 2012 6:23 am 
Juha Mäki-KantoJan 15, 2012 11:38 am 
Peter AmstutzJan 17, 2012 1:43 pm 
Stephen SwaneyJan 17, 2012 6:27 pm 
Subject:Re: [Bf-committers] Collada importer/exporter kickout
From:Juha Mäki-Kanto (kisk@gmail.com)
Date:Jan 15, 2012 11:38:18 am
List:org.blender.bf-committers

My basic point is that to me it seems like going to collada means you either haven't done object/armature animation yet or you're done with it and happy to have it "baked" as per frame rot/loc/scale or matrices. I'm not sure about most other programs so I'll just ask: what would be the correct way in collada to handle a parent inverse- matrix in child-objects (possibly has skew in it) and the "default" rest-pose attributed translation+rotation between parent-child bones?

2012/1/15 Juan Linietsky <redu@gmail.com>

The problem with importing/exporting of Collada and skeletons is not really that it doesn't match the internal representation. Animating 3D objects in a 3D Animation package is always done through euler angles, local or global, and that is easy to export seamlessly in Collada. But skeleton based models like characters almost always use IK or other sort of constraints which are impossible to convert back to euler due to gimbal lock issues, so the only way to reliably export skeletal animation is to export a full rotation snapshot either via a quaternion (which Collada does not support) or 4x3 matrix., and later optimize redundant keyframes to save storage space. So I think in short, it's the lack of support for constraints what makes Collada not very useful as an exchange format between DCCs, but yet it's still very useful for exporting to game engines.

On Sat, Jan 14, 2012 at 5:28 PM, Juha Mäki-Kanto <kisk@gmail.com

wrote:

The gist to me is that collada's transformations may not match a program's internal representation and reinterpreting usually goes via collada data to full matrix, possibly fix the matrix and then decomposite to curves. It's a lossy conversion, key's should match but interpolation won't -> you need to bake/key every frame when importing the curves.