Configuring Additive Animations for Procedural Movement

Students will create additive animation clips that layer subtle procedural movements over base animations to add realism to breathing and equipment weight.

In this lesson, you will learn how to create and implement additive animation clips to layer subtle, realistic procedural movements, such as breathing or equipment sway, over your existing character animations.

The Concept of Additive Animation

Standard animations define a pose by setting absolute transform values for bones. An Additive Animation, however, defines a difference (or delta) between a reference pose and an action. Instead of replacing the character’s posture, the engine calculates the offset and adds it to the current base pose. This allows you to stack a subtle "breathing" movement on top of a "walking" or "idle" animation without needing to create unique assets for every possible state.

Creating the Additive Clip

To create an additive clip:

Right-click your animation sequence in the Content Browser and select Create > Create Additive Animation.
You will be prompted to select a Base Pose Type.
- Choose Selected Animation Frame if you want the movement to be relative to a specific pose in your sequence.
- Choose Ref Pose if the movement is relative to the skeleton’s default T-pose.
Once created, Unreal generates a new asset that only stores the "delta" data. If you open this clip, you will see it only contains the joint rotations or positions that deviate from your chosen base pose.

Implementing in the AnimGraph

To apply this, head into your AnimGraph. Use the Apply Additive node.

Base: Connect your primary locomotion state (e.g., your Locomotion cache or Blend Space).
Additive: Connect your additive animation clip.
Alpha: This allows you to modulate the intensity of the effect. You can drive this with a Float variable to make breathing heavier when the character is exhausted or to calm it down when standing still.

// Logic flow in the AnimGraph
Base Pose -> Apply Additive (Additive Animation) -> Output Pose

By layering these, you avoid "animation bloat" where you would otherwise need to manually animate hundreds of variations to account for a character simply taking a breath while moving.

Key Takeaway: Additive animations allow you to layer procedural offsets on top of base movements, enabling complex behaviors like breathing or gear sway to coexist with your primary locomotion animations.