Exporting Additives (how it should be)

[Tectors]

Okay, you know exporting animations (normal) work and are perfectly fine and they are great, however something that has always been on my mind is additives and how the behavior of exporting them are.

Today, let's say you want to export the following animation from the game Fortnite:

Path: FortniteGame/Content/Animation/Game/MainPlayer/Locomotion/Medium/Male/Jog/Melee_TH/M_Jog_Melee_Twohanded_N
Additive Base Pose: FortniteGame/Content/Animation/Game/MainPlayer/Locomotion/Medium/Male/Jog/Melee_TH/M_Jog_Melee_Twohanded_N_Core

Now, when we export the additive, the bones are broken and miss-placed, for demonstration purposes:

And this is how the core animation looks like:

My theory is that the additives are exported wrong (obviously), but before telling you my theory let me explain to you what additives are in the first place (if you weren't aware).

Additives are basically a addition to a animation, to further add and possibly reuse for different purposes. Let's say you have a animation like a walking animation for the lower-body part of the game (for the legs walking part) and you have the upper-body moving along as the animation. What additives do is to take in a pose, for example the lower-body part with no upper-body movement and then have the same animation but contains the upper-body. They do this to have better performance and also being able to use the same additives across all different types of poses. They have a building tool pose animation, but have no additives and core animations? Well they just straight up use the Melee Twohanded additives.

Please tell me if you don't understand the above, you can read more about it on the internet. If you didn't get it already, a additive contains the core animation but adds to that core animation.

My theory is that you have to add the core animation to additive animation to have the final animation.