Intermediate Tutorial

Additive Animation

15 minutes

Posted on: May 31, 2018


animation fbx
Learn Sumerian
Additive Animation



In this tutorial you will learn about:


In this tutorial, you’ll learn about the concept of additive animation, and how to author and add this type of animation to a .fbx object in your Amazon Sumerian scene. We provide sample .fbx files that you can use with the Mannequin asset, which is available in the asset library.

You’ll learn about:

  • Differences between additive and override animation layers.
  • How to author additive animation in a Digital Content Creation (DCC) package.
  • How to apply additive animation in Sumerian.

We’ll start with a general overview of additive animation. If you’re already familiar with this concept, you can skip straight to the steps.

This is the scene we’ll build in this tutorial. For best results, be sure you are using the latest version of your browser.


Before you begin, you should have completed the following tasks and tutorials:

Additive Animation Overview

Sumerian has two types of animation layers: override and additive.

The default layer behavior is Override. If you add a new layer set to Override, that layer’s animations take priority and play instead of the animations on any layers underneath it. If layer blend weight is turned down on an override layer, the animation system will blend between the animation on the override layer and the animation on the layer underneath by the blend weight percentage. Because the very first layer doesn’t have any layers underneath it, it’s always forced to Override and doesn’t have a blend weight option.

An additive animation layer behaves very differently from an override animation layer. An additive animation layer adds its animation on top of the animations playing on layers underneath.

For example, you might have a character with several full body animation states on the first layer, like sitting, standing, and walking. To make that character wave without additive animation, you have to make sitting, standing, and walking versions of the wave animation. With additive animation, you can just animate the arm waving and import it on an additive layer on top of your first layer. Now the waving arm will add on top of the underlying animations, so you need only one wave animation. If layer blend weight is turned down on an additive layer, it only affects how much of the animation on the additive layer is playing. It doesn’t affect the underlying animations.

To achieve additive animation, Sumerian needs to know what the expected starting point for the animation is. This is also known as a reference pose. For the waving example, the reference pose would likely be one where the character’s arms are down at its side. This pose is subtracted out of all of the animation frames to make them relative to the reference pose. Sumerian always expects the reference pose to be the first frame in the animation. Once this frame is identified, it’s sliced off and stored so it won’t show up in the final result.

Next, we’ll go through how to author additive animations in a Digital Content Creation (DCC) package - software such as Maya, 3D Studio Max and Blender used for authoring digital content. We’ll be using Maya in our screenshots, but the concept is the same regardless of which tool you use to create animations.

Step 1: Author Additive Animations

  1. Create your animation as you normally would in the DCC package of your choice. In this example, we’ll use a looping wave animation.

  1. Expand your timeline so that one extra frame is available before your first keyframe.

  2. Set the current time to the new extra frame, and pose your character in its reference pose (described earlier in Additive Animation Overview).

  1. Export the entire animation, including the reference pose, as a .fbx file.

Step 2: Import Additive Animations

  1. Complete Step 1: Set up the Scene from the Animation Component tutorial.

  2. In the Entities panel, choose the Mannequin entity.

  3. In the Inspector panel, open the Animation component.

  4. Drop the sit_idle.fbx animation file onto the Drop Animation State Here box of the Default Animation Layer.

  1. Enable Loop Infinitely on the sit_idle animation state.

  1. Choose Add New Layer, located at the bottom of the Animation component.

  1. On the newly created layer, set the Layer Type to Additive.

  1. Drop the attached wave.fbx animation file onto the Drop Additive Animation State Here box of the additive layer.

  1. Enable Loop Infinitely on the wave animation state.

  2. Play the scene.

    You should see the Mannequin waving while idling in a standing pose.

  3. While the scene is still playing, navigate to the Default Animation Layer on the Animation component, and set the default state to sit_idle.

    You should now see the Mannequin waving while in a seated position.

Now publish and share your scene!

You should now have a much better understanding of override and additive animations. To learn more, check out the following tutorials:

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