How to use additive animation with a character that has an A-pose

Hey everyone. Not sure if I’m even framing this question right, but I’ll do my best.

I have a character that has a transforming arm. This arm has modular parts that can be added via a socket on the elbow. I have a morph target that essentially shrinks the rest of lower arm to animate it off and i need this morph animation to work with all my other animations.

What Happens:
When i run the game. My idle works fine. Once I press the transforming button. The idle snaps to it’s “A” Pose, and then plays the transform animation. (likely because it’s a blend shape) It then no longer returns to it’s idle, and now remains in it’s “A” Pose. I can get it to transform on and off however, and if I don’t use the specific morph anim, but use the others, it works fine.

What I Want to Happen:
I need the idle to run while the transform takes place. The morph anims are listed as local space Additive to the idle’s first frame. But this doesn’t stop it from snapping back to the mesh’s imported “A” Pose. I need clean transitions between the default state, animated intermediate state, and final transformation. I need these to work with additional animations later as well, like running, jumping, etc…

How do I even approach solving an issue like this? Can anyone point me in the right direction?

It would be nice having more details about how you implemented your animation switching system but from what I have understood I can tell the usual procedure to add these two animations would be:

  • create an anim blueprint
  • create anim montages from your idle and morph target animations
  • in your anim blueprint anim graph, add nodes “Play YouIdleMontage” and “Play YourMorphTargetMontage”
  • link the “Play Idle” node to a “New Saved Cached Pose” node.
  • link the Play “MorphTargetMontage” Node to a “Apply Additive” node.
  • create a “Pose Snapshot” node, set its name to the name of your previously cached pose and link it to the second pose of the Apply Additive Node.
  • link the Apply Additive Node the your final animation pose

If you want to implement any logic for switching from the idle animation to the morph target animation just set a variable in your event graph which will set the alpha value in the Apply Additive node.

However, if you want to remove all the idle animation occurring on the morph target animated arm and I am not sure if that is what you want. You can:

  • create some slots for your montages (the morph target montage should be on a slot for the arm only while the idle pose would be on a slot for the whole body except the previously set arm)
  • create snapshot poses from these 2 slots in your anim graph then blend them to the final pose.

Thanks for your suggestions! They worked.