Manipulating Materials in UE4

In this section, we'll be taking a look at how materials work in UE4.

Go back to your Level Viewport window and select this Cube object:

Figure 1.46: The Cube object, next to the text saying Third Person on the floor

Take a look at the Details window, where you'll be able to see both the mesh and material associated with this object's Static Mesh component:

Figure 1.47: The Static Mesh and Materials (Element 0) properties of the Cube object's Static Mesh component

Note

Keep in mind that meshes can have more than one material, but must have at least one.

Click the looking glass icon next to the Material property to be taken to that material's location in Content Browser. This icon works with any reference to any asset inside the editor, so you can do the same thing with the asset referenced as the cube object's Static Mesh:

Figure 1.48: The looking glass icon (left), which takes you to that asset's location in Content Browser (right)

Double-click that asset with the left mouse button to open that asset in the Material editor. Let's break down the windows present in Material editor:

Figure 1.49: The Material editor window broken down into five parts

1. Graph: Front and center in the editor, you have the Graph window. Similar to the Blueprint editor's Event Graph window, the Material editor's graph is also node-based, where you'll also find nodes connected by pins, although here you won't find execution pins, only input and output pins.
2. Palette: At the right edge of the screen, you'll see the Palette window, where you'll be able to search all the nodes that you can add to the Graph window. You can also do this the same way as in the Blueprint editor's Event Graph window by right-clicking inside the Graph window and typing the node you wish to add.
3. Viewport: At the top-left corner of the screen, you'll see the Viewport window. Here, you'll be able to preview the result of your material and how it will appear on some basic shapes such as spheres, cubes, and planes.
4. Details: At the bottom-left corner of the screen, you'll see the Details window where, similar to the Blueprint editor, you'll be able to see the details of either this Material asset or those of the currently selected node in the Graph window.
5. Toolbar: At the top edge of the screen, you'll see the Toolbar window, where you'll be able to apply and save the changes made to your material, as well as to perform several actions related to the Graph window.

In every single Material editor inside UE4, you'll find a node with the name of that Material asset, where you'll be able to specify several parameters related to it by plugging that node's pins to other nodes.

In this case, you can see that there's a node called 0.7 being plugged into the Roughness pin. This node is a Constant node, which allows you to specify a number associated with it – in this case, 0.7. You can create constant nodes of a single number, a 2 vector (for example, (1, 0.5)), a 3 vector (for example, (1, 0.5, 4)), and a 4 vector (for example, (1,0.5, 4, 0)). To create these nodes, you can press the Graph window with the left mouse button while holding the 1, 2, 3, or 4 number keys, respectively.

Materials have several input parameters, so let's go through some of the most important ones:

• BaseColor: This parameter is simply the color of the material. Generally, constants or texture samples are used to connect to this pin, to either have an object be a certain color or to map to a certain texture.
• Metallic: This parameter will dictate how much your object will look like a metal surface. You can do this by connecting a constant single number node that ranges from 0 (not metallic) to 1 (very metallic).
• Specular: This parameter will dictate how much your object will reflect light. You can do this by connecting a constant single number node that ranges from 0 (doesn't reflect any light) to 1 (reflects all the light). If your object is already very metallic, you will see little to no difference.
• Roughness: This parameter will dictate how much the light that your object reflects will be scattered (the more the light scatters, the less clear this object will reflect what's around it). You can do this by connecting a constant single number node that ranges from 0 (the object essentially becomes a mirror) to 1 (the reflection on this object is blurry and unclear).

  Note

  To learn more about material inputs like the ones above, go to https://docs.unrealengine.com/en-US/Engine/Rendering/Materials/MaterialInputs.

UE4 also allows you to import images (.jpeg, .png) as Texture assets, which can then be referenced in a material using Texture Sample nodes:

Figure 1.50: The Texture Sample node, which allows you to specify a texture and use it or its individual color channels as pins

Note

We will be taking a look at how to import files into UE4 in the next chapter.

In order to create a new Material asset, you can do so by right-clicking on the directory inside Content Browser where you want to create the new asset, which will allow you to choose which asset to create, and then select Material.

Now you know how to create and manipulate materials in UE4.

Let's now jump into this chapter's activity, which will be the first activity of this book.

Activity 1.01: Propelling TestActor on the Z Axis Indefinitely

In this activity, you will use the Tick event of TestActor to move it on the Z axis indefinitely, instead of doing this only once when the game starts.

The following steps will help you complete this activity:

1. Open the TestActor Blueprint class.
2. Add the Event Tick node to the Blueprint's Event Graph window.
3. Add the AddActorWorldOffset function, split its DeltaLocation pin, and connect the Tick event's output execution pin to this function's input execution pin, similar to what we did in Exercise 1.01, Creating an Unreal Engine 4 Project.
4. Add a Float Multiplication node to Event Graph window.
5. Connect the Tick event's Delta Seconds output pin to the first input pin of the Float Multiplication node.
6. Create a new variable of the float type, call it VerticalSpeed, and set its default value to 25.
7. Add a getter to the VerticalSpeed variable to the Event Graph window and connect its pin to the second input pin of the Float Multiplication node. After that, connect the Float Multiplication node's output pin to the Delta Location Z pin of the AddActorWorldOffset function.
8. Delete the BeginPlay event and the AddActorWorldOffset function connected to it, both of which we created in Exercise 1.01, Creating an Unreal Engine 4 Project.
9. Play the level and notice our TestActor rising from the ground and up into the air over time:
   

Figure 1.51: The TestActor propelling itself vertically

And with those steps completed, we conclude this activity – the first of many in this book. We've now consolidated adding and removing nodes to and from the Blueprint editor's Event Graph window, as well as using the Tick event and its DeltaSeconds property to create game logic that maintains consistency across different frame rates.

Note

The solution to this activity can be found at: https://packt.live/338jEBx.

The TestActor blueprint asset can be found here: https://packt.live/2U8pAVZ.