Hello @jblower ,
For most fbx files with animation there are 'takes' in the fbx which contain the individual animations. Often times they are just consecutive in the timeline and in Max Interactive, Unity, or UDK you just call animations from certain frames. It really depends on the file. What you should do is File-> Import and select your FBX. Then go to the animation section of the import window and see if you have multiple takes. If the default one doesn't have an animation on it, a second one might.
It sounds like your file is setup for use in Max Interactive, Unity, and UDK which normally would be where you retime these things. Importing it back into max to break it into clips isn't something I've done exactly. A good place to start learning about it is probably here. If it let's you save an XAF I suppose you can then probably use the motion mixer with it and save yourself tons of hassle by managing clips with the interface instead of fussing around with keyframe scaling in the curve editor. After you'd saved out each animation as a clip you could take a version of your character without animation and then motion mix it. At least, in theory.
It's going to take some time to get the hang of it, and I recommend any tutorials that come with 3dsmax on those ideas above. Also, I tend to do everything but character animation so there are likely some people out there with much better ways of doing this.
Best Regards,
Alfred (AJ) DeFlaminis
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