I'll give writing my own little mix over time class a go then. Native support for such mixing would be awesome though! Thanks for the fast info and for considering it.

Thanks for the info guys! Really helped me understand how tracks and states work.
I managed to do what I wanted by storing a pointer to the TrackEntry returned by setAnimation like you suggested Nate and doing some interpolation over time for smooth transitions. Works really well and is easy to add more stuff upon!

Got another question and figured I might as well use the same thread...
Is there any way to use the default AnimationState system and mix in/out an animation on an empty track? Say for example I have two tracks: Track 0 is used to play a run animation which animates the entire skeleton. Track 1 is used to animate the arms only. When starting an animation on track 1 it's not mixed in (I'm guessing this is intended behaviour) which results in the bones snapping to their starting positions.
Is mixing between tracks like this possible or would it have to be done manually?

Hi there!
I'm using the Spine-C and Spine-SFML runtimes and I've got two animations set up for a character moving: One where he is running and one where he is walking. Both animations are of equal length and sync up perfectly. What I'm trying to do is play both simultaneously and blend between them based on some scalar value (like the speed the character is moving). The movement speed of the character is based on analogue input so just switching to a different animation with a blend duration won't work (and would also desync the skeleton between the animations). My first thought on how to do this was through some kind of track mixing but looking at the documentation it is not immediately clear to me how to do this, or if it is even possible, hence my question is: Is it?
Thanks!