12. Animation Blending and Montages

Overview

By the end of this chapter, you will be able to use the Animation Montage tool to create a unique throwing animation using the Throw animation sequence you imported in Chapter 10, Creating a SuperSideScroller Game. With this montage, you will create and use Anim Slots that will allow you to blend animations in the Animation Blueprint for the player character. You will also get to know how to use blending nodes to effectively blend the movement and throwing animations of the character.

After finalizing the player character animation, you will create the required class and assets for the enemy AI and learn more about Materials and Material Instances, which will give this enemy a unique visual color so that it can be differentiated in-game. Finally, the enemy will be ready for Chapter 13, Enemy Artificial Intelligence, where you will begin to create the AI behavior logic.

Introduction

In the last chapter, you were able to bring the player character to life by implementing movement animations in a Blend Space and using that Blend Space in an Animation Blueprint to drive the animations based on the player's speed. You were then able to implement functionality in C++ based on player input to allow the character to sprint. Lastly, you took advantage of the animation state machine built-in Animation Blueprints to drive the character movement state and jumping states to allow fluid transitions between walking and jumping.

With the player character Animation Blueprint and state machine working, it's time to introduce Animation Montages and Anim Slots by implementing the character's Throw animation. In this chapter, you will learn more about animation blending, see how Unreal Engine handles the blending of multiple animations by creating an Animation Montage, and work with a new Anim Slot for the player's throwing animation. From there...

Animation Blending, Anim Slots, and Animation Montages

Animation blending is the process of transitioning between multiple animations on a skeletal mesh as seamlessly as possible. You are already familiar with the techniques of animation blending because you created a Blend Spaces asset for the player character in Chapter 11, Blend Spaces 1D, Key Bindings, and State Machines. In this Blend Space, the character smoothly blends between the Idle, Walking, and Running animations. You will now extend this knowledge by exploring and implementing new additive techniques to combine the movement animations of the character with a throwing animation. Through the use of an Anim Slot, you will send the throwing animation to a set of upper body bones, and its children's bones, to allow movement and throwing animations to apply at the same time without negatively impacting the other. But first, let's talk more about Animation Montages.

Animation Montages are a very powerful asset that...

Animation Montages

Have a look at the following figure:

Figure 12.3: The animation Preview window in the Animation Montage Persona editor

Underneath the Preview window, you have the main montage timeline, in addition to other sections; let's evaluate these sections from top to bottom:

• Montage: The Montage section is a collection of animations that can add one or more animations to. You can also right-click on any point in the timeline to create a section. Sections allow you to compartmentalize the different parts of the montage into their own self-contained section that can be referenced and manipulated in the Sections area.
• Sections: Sections, as mentioned before, allow you to set the order of how the individual animation sequences are played and whether a section should loop.

For the purposes of the throw montage, you do not need to use this feature since you will only be using one animation in this montage:

...

Anim Slot Manager

Anim Slot Manager is where you, as the name suggests, manage your Anim Slots. From this tab, you can create new Groups, which allow greater organization of your slots. For example, you can create a Group by left-clicking on the Add Group option and labeling it Face to articulate to others that the slots within this group affect the face of the character. By default, Unreal Engine provides you with a Group called DefaultGroup and an Anim Slot called DefaultSlot that is in that group.

Let's create a new Anim Slot.

Exercise 12.03: Adding a New Anim Slot

Now that you have a better understanding of Anim Slots and Anim Slot Manager, you can follow these steps to create a new Anim Slot, which you will call Upper Body. Once you have this new slot created, it can then be used and referenced in your Animation Blueprint to handle animation blending, which you will do in a later exercise.

Let's create the Anim Slot by doing the following:

...

Save Cached Pose

There are cases when working with complex animations and characters requires you to reference a pose that is outputted by a state machine in more than one place. If you hadn't noticed already, the output pose from your Movement state machine cannot be connected to more than one other node. This is where the Save Cached Pose node comes in handy; it allows you to cache, or store, a pose that can then be referenced in multiple places at once. You will need to use this to set up the new Anim Slot for the upper body animation.

Let's get started.

Exercise 12.04: Save Cached Pose of the Movement State Machine

To effectively blend the Throw animation, which uses the Upper Body Anim Slot you created in the previous exercise with the movement animations already in place for the player character, you need to be able to reference the Movement state machine in the Animation Blueprint. To do this, do the following to implement the Save Cached Pose node in the...

Layered blend per bone

The node that you will use to blend animations here is Layered blend per bone. This node masks out a set of bones on the character skeleton for an animation to ignore those bones.

In the case of our player character and the Throw animation, you will mask out the lower body so that only the upper body animates. The goal is to be able to perform the throw and movement animations at the same time and have these animations blend together; otherwise, when you perform the throw, the movement animations would completely break.

Exercise 12.05: Blending Animation with the Upper Body Anim Slot

The Layered blend per bone function allows us to blend the Throw animation with the movement animations you implemented in the previous chapter, and give you control over how much influence the Throw animation will have on the player character skeleton.

In this exercise, you will use the Layered blend per bone function to completely mask out the lower body of the character...

The Throw Animation

So far, you have put a lot of work into ensuring that the Throw animation blends correctly with the Movement animations that you set up in the Animation Blueprint in the previous chapter. The main reason behind this effort is to ensure the visual fidelity of the character when performing multiple animations at once. You will learn first-hand the visual consequences of incorrectly setting up animation blending in the exercises and activity ahead.

Getting back to the Throw animation, every modern video game implements animation blending in one form or another, so long as the art direction and the game mechanics require such a feature. An example of a modern game franchise that extraordinarily uses animations is the Uncharted series developed by Naughty Dog.

If you are unfamiliar with the franchise, you can watch the full gameplay of the latest installment here: https://www.youtube.com/watch?v=5evF_funE8A.

What the Uncharted series does very well is use thousands...

The Super Side Scroller Game Enemy

With the player character animating correctly when moving and performing the Throw animation, it is time to talk about the enemy type that the SuperSideScroller game will feature. We will have a simple type of enemy.

This enemy will have a basic back-and-forth movement pattern and will not support any attacks; only by colliding with the player character will it be able to inflict damage.

In the next exercise, you will set up the base enemy class in C++ for the first enemy type and configure the enemy's Blueprint and Animation Blueprint in preparation for Chapter 13, Enemy Artificial Intelligence, where you will implement the AI of this enemy. For the sake of efficiency and time, you will use the assets already provided by Unreal Engine 4 in the SideScroller template for the enemy. This means you will be using the skeleton, skeletal mesh, animations, and the Animation Blueprint of the default mannequin asset. Let's begin by creating...

Materials and Material Instances

Before moving on to the next exercise, we need to first briefly discuss what Materials and Material Instances are before you can work with these assets and apply them to the new enemy character. Although this book is more focused on the technical aspects of game development using Unreal Engine 4, it is still important that you know, on a surface level, what Materials and Material Instances are and how they are used in video games.

Note

For more information about Materials, please refer to the following Epic Games documentation: https://docs.unrealengine.com/en-US/Engine/Rendering/Materials/index.html.

A Material is a type of asset that can be applied to a mesh that will then control how the mesh looks in-game. The Material editor gives you control over many parts of how the end visual result will look, including control over parameters such as Textures, Emissive, and Specular, among others. The following image shows the default mannequin skeletal...

Summary

With the enemy set up with the C++ class, Blueprint, and Material, you are ready to move on to the next chapter, where you will create the AI for this enemy by taking advantage of systems such as Behavior Trees in Unreal Engine 4.

From the exercises and activities of this chapter, you learned how to create an Animation Montage that allows the playing of animations. You also learned how to set up an Anim Slot within this montage to categorize it for the player character's upper body.

Next, you learned how to cache the output pose of a state machine by using the Use Cached Pose node so that this pose can be referenced in multiple instances for more complex Animation Blueprints. Then, by learning about the Layered blend per bone function, you were able to blend the base movement pose with the additive layer of the Throw animation by using the Anim Slot.

Lastly, you put together the base of the enemy by creating the C++ class, Blueprint, and other assets so that they...