Advanced Blend Tree Techniques

Introduction

Blend Trees are powerful tools that cover a variety of use cases, from optimizing simple animator layers, to simulating complex logic equations.

For an introduction to Blend Trees, check out Combining Layers Using Direct Blend Trees to optimize simple animator layers and save animator performance.

This article covers more advanced applications of Blend Trees, including:

• Logic Gates
• Float Remapping*
• Math Operators*
• Framerate Detection*
• Float Smoothing*

*Many applications are an extension of the Animated Animator Parameters (AAP) article, so it’s recommended to have read its contents.

<aside> ⚠️ When using Direct Blend Trees, don’t forget to make their states Write Defaults enabled, and mark their states with (WD ON) in the name.

</aside>

Example images in this article use MACS for visualization.

• Numbers on the left of animations/Blend Trees show their Threshold in a 1D/2D Blend Tree
• Names on the left of animations/Blend Trees show their Direct Blend Parameter
• If an animation is named [Parameter][Number] it animates that AAP to that number. Output1 for example animated the Output AAP to 1

For example, on the right you will see a Direct ([DIR]) Blend Tree that animates a Standard 1D ([S1D]) Blend Tree with a weight parameter of One. That Blend Tree has two children, one animation clip Output-100 at threshold -100, and another animation clip Output100 at threshold 100.

Direct and 1D Blend Trees are the only types that follow simple mathematical rules, while the other types have advanced algorithms not meant for logic but for animation, and are at best an approximation.

An example of the visualizations used in this article. This layer would save the Output AAP according to the 1D Blend Tree technique.

Logic Gates

You can use Blend Trees to simulate the logic of logic gates (like AND, OR, NOT, XOR, etc.).

These can be used to animate properties based on multiple input parameters, such as toggling a GameObject off when toggling another GameObject on, or animating a blendshape only when two other toggles are enabled.

The following examples assume 1 = True and 0 = False.

AND Gate

Output true, only if A and B are both true

This example demonstrates an AND Gate using parameters InputA and InputB.

Here, the only way the Output animation plays is if both inputs are 1 (true).

Example template can be downloaded from Logic: AND Gate.

An example of an AND gate.