Mac OSX (intel) 10.5.8 (Nvidia 9600)
Steps to reproduce:
- create a new file with the default cube
- insert 2 key frames, e.g. move the cube along Z
(by default this will use bezier interpolation)
- export file as .dae (collada)
In the exported file the animation will be using LINEAR interpolation, and won't contain tangent data.
The .dae file will have the animation listed using BEZIER interpolation and contain tangent data.
I've attached .blend and .dae if it helps.
It appears that the exporter is sampling the F-Curves so that they will take into account F-Modifiers etc. too instead of just outputting the raw keyframes. This approach should allow other apps to reproduce the same results, at the expense of animators not being able to edit those exact keyframes (though in my biased opinion, why should anyone want/need to do so in other apps anymore!)
Anyways, will leave for Arystan to make final call on this.
Hmmm, is there anyway to control how this sampling is done, as in the attached example files the .dae output just has LINEAR interpolation between the two keyframes, which obviously isn't the same as the nice ease in/out you get with BEZIER interpolation. In my case, I wouldn't mind having the exporter re-sample the f-curve as linear segments (as long as they reasonably resemble the original curve), but as Joshua mentions this will make the data pretty useless, if you want to import the .dae in some other tool and manipulate the animation there.
Currently not too much time to work on this, so I'm moving this to our todo list on the wiki: http://wiki.blender.org/index.php/Dev:2.5/Source/Development/Todo/Simple_Todos#COLLADA
Anyone who wants to help out still can provide patches!
Thanks for reporting.