Hey, for only a few months of experience they're really awesome already! (And I'm always happy if I can help someone - even though I'm far from being a veteran myself
)
Quote: Animation controls aren't supported by the HPL engine, so it's strictly joint rotation(to my knowledge, at least) and sometimes the animations don't import as smoothly as I would like them to. Ah well.
Oh, don't worry, they don't need to be supported, you'd still only export joint rotation (and translation maybe but that should work too). You see, it's often easier not to animate joints or IK handles directly, but instead to create a control rig around them, consisting of simple Circles or Locators or whatever that influence the joints via constraints. (Orient constraint, Parent constraint or Point constraint in Maya, but I'm sure similar functions can be found in any 3D program) These aren't exported, they're just there to make life easier for the animator
Depending on how you export the animation you might need to bake the animation onto the joints before exporting though (select all joints, then edit>keys>bake simulation if you're in Maya)...
Having a control rig can make animating a lot easier because the controls are easier to select in the viewport (especially stuff like fingers etc), you can have one control that drives the movement of many joints and you can do neat stuff with driven keys and custom attributes and whatnot. My giant Bird for example has one big control for each wing with attributes like "fold wing" or "bend feathers" so I don't have to select and rotate each of the 30
or so joints in it by hand anymore. (which would be a pain to do ^^)
Its definitely more complicated at first to make a control rig instead of animating the joints directly, but it really helps in the long term. (Its also a bit safer, because joints are more prone to bugs and weirdnesses than NURBs curves, so if your animation is on those you can just replace the buggy joints with new ones if something goes wrong and re-do the constraints.)
Anyway, controls or not, baking the animation could also help you if your animation exports weirdly, because it means that Maya puts a key on every frame so the engine doesn't need to interpret any curves and tangents anymore. (Don't forget to make a backup of your file first, editing a baked animation is painful
) I don't know anything about HPL engine though, so I don't know if it would help... Might be worth a try though.