If you happen to be old enough to know a world without youtube and like the written word (like a tutorial), tough time for you.
So if you want to learn, say about using Unity's main animation tool Mecanim, but also happen to *HATE* tutorial videos (because they waste your precious time) you're in deep shit. I'm not saying that Unity's tutorial videos are shit, but watching 30 minutes of someone talking away for an information that fits on 2 lines of written text (and maybe a screenshot) ... well, you get my point.
Fear not, we have written words (and screenshots)
Let's start by wasting some space with the basic problem: You have a character, animated him (or her) and want to use it in Unity. I might need to point out that I'm NOT using Blender (so things may be a bit different for you, but the basics still apply).
That's Violet and the odd 850 frames needed to animate her.
Let's fast forward the export and import process and jump right to the part you'd do if you haven't watched any tutorial video on setting up anims or re-targeting them in Unity.
After you're done setting up the animation clips you might end up with something like this:
(taken from a character that needs updating)
In a way you're set and can start setting up the animator's state machine, but what if you change the model or need to update / change the animation? Well you end up re-creating all the clips. Joy.
After the second time it becomes some sort of a curse.
If you have at least read the Unity manual on this (which is [again] very much lacking useful examples), you should know that you can re-target animations between models that share the same bone structure. But you may have (like me) overlooked the fact that this also solves the problem of re-doing the clips over and over again when you update your character.
Exporting the character to use with Mecanim
(This headline is just there to ensure google finds this post)
This process might be a bit more work when starting, but it saves a shit load afterwards. Let's start with exporting the "base" (and NOT animated character). In my case I select the skin and bones and hit "export selected" and get this dialog:
I should have exported the base model in T-pose and without animations, though (makes it easier to create a ragdoll).
Anyway, that's done, go to Unity and import and setup the base model:
Note that there are no animations to be imported.
Exporting animations and setting them up in Unity to be used with the base model (and re-target them)
Now it's time to swap the tedious process of setting up the animation clips in Unity with the tedious process of exporting the animation clips from our 3D app (although, this is the by far better choice in the long run).
The trick is, that this time I only select the bones when clicking "export selected" and the important part of this dialog is "bake animations" and the option to give a start and end frame (hint, hint).
Actually, you could of export the skin again, but there really is no need to do so.
And after (what felt like an hour) I've got my clips exported and in Unity.
Preparing for re-targeting the animations
The tutorial video needs about 17 minutes to explain all that shit, but we can get the important information from a single screenshot:
When importing the animation, we copy the rig from an existing model (the base model) and click apply. Now set up the animation clip by changing to "Animations" and because we only exported the needed frames it's just changing the name from "Take 0001" to something meaningful (and maybe go over the other options of the clip, like looping).
That's it. Now you can just setup the animator state machine as before. Violet's looks like this right now:
Viola! A bit of text, some screenshots and no need to watch 30 minutes of video. Mhm, but then it took me about 2 hours to write this ...
... I think I better start making videos.