Hi.
Is it true that when we import a FBX or USD animations sequence into Unreal, that the Unreal importer flattens the incoming tangents associated with the key points? If so, is there a way to preserve tangents when going from Maya into Unreal?
Thanks!
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Steps to Reproduce
Import a FBX/USD file at 30 hz, set Unreal to run faster than 30 hz and graph the output.
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Upon further research, it’s not that it actually flattens the tangents, it appears to ignore any tangent settings and force a linear interpolation between keyframes? Is there a way to bring in custom tangents?
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Hey there,
Unfortunately no. The animsequence data format only stores interpolated frames. For games, the tangent data would be too heavy. Our recommendation for licensees that make heavy use of tangent data is to sample animations that require it at a higher rate during import (or from export if you’re animating in the engine).
Dustin
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Thanks for the reply Dustin. I read another post that seemed to imply that some other sequence types do store non-linear tangents? Is that true? If so, is there somewhere that calls this out? For our particular use case, we really need the tangent data and while we can sample at a higher rate we still eventually run into the linear step issue. Thanks!
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Sequencer animation tracks use rich curve data, and that is where we can store tangent data for playback when animating in the engine and for cinematic/film work. You can import animation into sequencer and it will have tangent support, but the issue is that for bone animation, that playback would need to be on a control rig. Generating an FK control rig setup for the character in your sequence to then play the animation on. Then you can right-click on that control rig and Import Control Rig FBX to get that animation.
Dustin
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