This is not entirely true:
https://docs.unity3d.com/Documentation/Manual/HOWTO-ImportObjectMaya.html
Unity natively imports Maya files. To get started, simply place your .mb or .ma file in your project’s Assets folder.
…
if i remember correctly (it’s many years since i have used maya), if you look at a maya file you will see that they are basically mel scripts that create the saved scene. so importing maya files without maya is quite impossible except for very limited cases. all tools i knew that “directly” opened maya files used maya on the command line in the background to achieve it.
“In order to import Maya .mb and .ma files, you need to have Maya installed on the machine you are using Unity to import the .mb/.ma file.”
So no, that’s not what I’d personally call native.
They describe it like this later on: “When Unity imports a Maya file it will launch Maya in the background. Unity then communicates with Maya to convert the .mb file into a format Unity can read. The first time you import a Maya file in Unity, Maya has to launch in a command line process, this can take around 20 seconds, but subsequent imports will be very quick.”
So yes, what Bloodwork said is still accurate.
I did some tests last weekend using Blender, Unreal 4 and fbx converter. It works just like it does in Unity except for two steps. I setup my character with in Blender with Rigify, exported the fbx to a raw folder in Unreal 4 where I import to the engine. I first tried changing the model as a test. All I had to do is export the fbx, convert it to a newer version (which I’m not even sure is necessary) then reimport and voila! Then I made some animation. You can import animation without even touching the original character in Unreal 4 and it works perfectly. I had to scale him up in Unreal but that didn’t break anything. You don’t have to redo any shader work when reimporting the asset. I animated a whole walk cycle to make sure it was 1:1 in the engine and it was perfect.
I’m not sure how we could ask for anything more. I’ll try and play with it more this weekend to see if there is something that doesn’t work. I haven’t looked at smoothing yet. I have a trick to deal with smooth and flat polies being next to each other. I’ll see if it works the same in U4.