Blueprints Visual Scripting for Unreal engine

Chapter 1. Object Interaction with Blueprints

When setting out to develop a game, one of the first steps toward exploring your idea is to build a prototype. Fortunately, Unreal Engine 4 and Blueprints make it easier than ever to quickly get the essential gameplay functionality working so that you can start testing your ideas sooner. To develop some familiarity with the Unreal editor and Blueprints, we will begin by prototyping simple gameplay mechanics using some default assets and a couple of Blueprints.

In this chapter, we will cover the following topics:

Creating a new project and a level
Placing objects in a level
Changing an object's material through Blueprints
Using the Blueprint editor and connecting Blueprints together
Compiling, saving, and playing our game
Moving objects in the world with Blueprints

Creating a project and the first level

Before we can begin setting up gameplay elements, we need to create a project that will contain the content of our game. To access Unreal Engine 4 and begin setting up our project, we must first open the Epic Games Launcher, which can be downloaded from the Unreal Engine 4 website (https://www.unrealengine.com/). From the Epic Games Launcher, click on the tab labeled Unreal Engine. If you are using Unreal Engine on your computer for the first time, you will see a grayed out-button labeled Not Installed. Along the left-hand side of the launcher, you will see options.

The Library tab is the location where you will be able to access the versions of the engine you have installed and the projects you have built. Now click on the Library tab, find the yellow Install button (as seen in the following screenshot), and click on it:

Creating the project

Now that we have a template selected and the project settings set up the way we like, we can create the project. To do so, click on the green Create Project button. After the engine is done with initializing the assets and setting up your project, Unreal Editor will open Level Editor, where you can create and view levels, place and modify objects, and test your game as you modify it.

Pressing the Play button, as shown in the following screenshot, along the top of the toolbar, will allow you to try the default gameplay that comes built into the First Person template. This includes player movement, shooting a simple projectile, and using projectiles to apply force to primitive box objects. In play mode, the Play button will be replaced with a Pause button and a Stop button. You can press the Pause button to temporarily halt the play session, which can be useful when you want to explore the properties of an interaction or actor that you just encountered during gameplay. Pressing the Stop button will end the play session and take you back to editing mode. Go ahead and try playing the game before we continue.

Adding objects to our level

Now we want to start adding our own objects to the level. The central panel you see in Level Editor is known as 3D Viewport. A viewport allows you to see the 3D content of the game, and it is important that you become familiar with navigating inside this panel. The viewport can be navigated by moving the camera around using a combination of mouse buttons and its movement. Holding down the left mouse button and dragging the mouse pointer inside the viewport moves the camera view forward and backward, or left and right. Holding down the right mouse button and moving the mouse allows you to look around by rotating the camera. Finally, holding down either the middle mouse button or a combination of both the left and right mouse buttons will allow you to drag the camera up and down.

The simplest kind of object that can be dragged into the game world in Unreal Engine 4 is called an actor. An actor is a basic object with no inherent behavior other than the ability to be rotated, moved, and scaled, but it can be expanded to include more complex behavior by attaching components. Our goal will be to create a simple target actor that will change color when shot with the included gun and projectile. We can create a simple actor by going to the Modes panel. With the Place tab selected, click on Basic and then drag the object called Cylinder into the 3D Viewport. This will create a new cylinder actor and place it in our level. You should see the actor in the 3D Viewport as well as in the Scene Outliner panel, where it will be named Cylinder by default. Right-click on this object in the Scene Outliner panel, go to Edit, and then select Rename. Rename the Cylinder object to CylinderTarget, as shown here:

Exploring materials

Earlier, we set for ourselves the goal of changing the color of the cylinder when it is hit by a projectile. To do so, we will need to change the actor's material. A material is an asset that can be added to an actor's mesh (which defines the physical shape of the actor) to create its look. You can think of a material as paint applied on top of an actor's mesh or shape. Since an actor's material determines its color, one method of changing the color of an actor is to replace its material with a material of a different color. To do this, we will first be creating a material of our own. It will make an actor appear red.

Creating materials

We can start by creating a new folder inside the FirstPersonBP directory and calling it Materials. Navigate to the newly created folder and right-click inside empty space in the content browser, which will generate a new asset creation popup. From here, select Material to create a new material asset. You will be prompted to give the new material a name, which I have chosen to call TargetRed.

Material properties and Blueprint nodes

Double-click on TargetRed to open a new editor tab for editing the material, like this:

You are now looking at Material Editor, which shares many features and conventions with Blueprints. The center of this screen is called the grid, and this is where we will place all the objects that will define the logic of our Blueprints. The initial object you see in the center of the grid screen, labeled with the name of the material, is called a node. This node, as seen in the previous screenshot, has a series of input pins that other material nodes can attach to in order to define its properties.

To give the material a color, we will need to create a node that will give information about the color to the input labeled Base Color on this node. To do so, right-click on empty space near the node. A popup will appear, with a search box and a long list of expandable options. This shows all the available Blueprint node options that we can add to this Material Blueprint. The search box is context sensitive, so if you start typing the first few letters of a valid node name, you will see the list below shrink to include only those nodes that include those letters in the name. The node we are looking for is called VectorParameter, so we start typing this name in the search box and click on the VectorParameter result to add that node to our grid:

A vector parameter in the Material Editor allows us to define a color, which we can then attach to the Base Color input on the tall material definition node. We first need to give the node a color selection. Double-click on the black square in the middle of the node to open Color Picker. We want to give our target a bright red color when it is hit, so either drag the center point in the color wheel to the red section of the wheel, or fill in the RGB or Hex values manually. When you have selected the shade of red you want to use, click on OK. You will notice that the black box in your vector parameter node has now turned red.

Tip

Downloading the example code

You can download the example code files from your account at

Adding substance to our material

We can optionally add some polish to our material by taking advantage of some of the other input pins on the material definition node. 3D objects look unrealistic with flat, single color materials applied, but we can add additional reflectiveness and depth by setting a value for the materials Metallic and Roughness inputs. To do so, right click in empty grid space and type scalar into the search box. The node we are looking for is called ScalarParameter.

We have now made a shiny red material. It will ensure that our targets will stand out when they are hit. Click on the Save button in the top-left corner of the editor to save the asset, and click again on the tab labeled FirstPersonExampleMap to return to your level.

Creating our first Blueprint

We now have a cylinder in the world, and the material we would like to apply to the cylinder when shot. The final piece of the interaction will be the game logic that evaluates that the cylinder has been hit, and then changes the material on the cylinder to our new red material. In order to create this behavior and add it to our cylinder, we will have to create a Blueprint. There are multiple ways of creating a Blueprint, but to save a couple of steps, we can create the Blueprint and directly attach it to the cylinder we created in a single click. To do so, make sure you have the CylinderTarget object selected in the Scene Outliner panel, and click on the blue Blueprint/Add Script button at the top of the Details panel. You will then see a path select window.

For this project, we will be storing all our Blueprints in the Blueprints folder, inside the FirstPersonBP folder. Since this is the Blueprint for our CylinderTarget actor, leaving the name of the Blueprint as the default, CylinderTarget_Blueprint, is appropriate.

CylinderTarget_Blueprint should now appear in your content browser, inside the Blueprints folder. Double-click on this Blueprint to open a new editor tab for the Blueprint. We will now be looking at the Viewport view of our cylinder. From here, we can manipulate some of the default properties of our actor, or add more components, each of which can contain their own logic to make the actor more complex. We will explore components more in the next chapter; for now, we want to create a simple Blueprint attached to the actor directly. To do so, click on the tab labeled Event Graph above the Viewport window.

Exploring the Event Graph panel

The Event Graph panel should look very familiar, as it shares most of the same visual and functional elements as the Material Editor we used earlier. By default, the event graph opens with three unlinked event nodes that are currently unused. An event refers to some action in the game that acts as a trigger for a Blueprint to do something. Most of the Blueprints you will create follow this structure: Event (when) | Conditionals (if) | Actions (do). This can be worded as follows: when something happens, check whether X, Y, and Z are true, and if so, do this sequence of actions. A real-world example of this might be a Blueprint that determines whether or not I have fired a gun. The flow is like this: WHEN the trigger is pulled, IF there is ammo left in the gun, DO fire the gun.

The three event nodes that are present in our graph by default are three of the most commonly used event triggers. Event Begin Play triggers actions when the player first begins playing the game. Event Actor Begin Overlap triggers actions when another actor begins touching or overlapping the space containing the existing actor controlled by the Blueprint. Event Tick triggers attached actions every time a new frame of visual content is displayed on the screen during gameplay. The number of frames that are shown on the screen within a second will vary depending on the power of the computer running the game, and this will in turn affect how often Event Tick triggers the actions.

We have now done everything we need with this Blueprint to turn the target cylinder red, but before the Blueprint can be saved, it must be compiled. Compiling is the process used to convert the developer-friendly Blueprint language into machine instructions that tell the computer what operations to perform. This is a hands-off process, so we don't need to concern ourselves with it, except to ensure that we always compile our Blueprint scripts after we assemble them. To do so, hit the Compile button in the top-left corner of the editor toolbar, and then click on Save.

Now that we have set up a basic gameplay interaction, it is wise to test the game to ensure that everything is happening the way we expect. Click on the Play button, and a game window will appear directly above the Blueprint Editor. Try both shooting and running into the CylinderTarget actor you created.

FirstPersonProjectile is a Blueprint included in Unreal Engine 4's First Person template that controls the behavior of the projectiles that are fired from your gun. This node uses casting to ensure that the action attached to the execution pin of this node occurs only if the actor hitting the cylinder target matches the object referenced by the casting node.

When the node appears, you should already see a blue wire between the Other output pin of the Event Hit node and the Object pin of the casting node. If not, you can generate it manually by clicking and dragging from one pin to the other. You should also remove the connections between the Event Hit and Set Material node execution pins so that the casting node can be linked between them. Removing a wire between two pins can be done by holding down the Alt key and clicking on a pin.

Once you have linked the three nodes, the event graph should look like what is shown in the following screenshot:

Now compile, save, and click on the play button again to test. This time, you should notice that the cylinder target retains its default color when you walk up and touch it, but does turn red when fired upon by your gun.

Adding movement

Now that we have a target that responds to the player shooting, we can add some sort of challenge to start making our project feel like a game. A simple way to do this is to add some movement to our target. To accomplish this, we will first have to declare that our target actor is an object that is intended to move, and then we need to set up logic within the Blueprint that will manage how it moves. Our goal will be to make the target cylinder move back and forth across our level.

Changing actor mobility and collision

To allow our target to move, we first have to change the actor's Mobility setting to Moveable. This allows an object to be manipulated while playing the game. From the main editor view, select CylinderTarget_Blueprint, and look at the Details panel. Underneath the Transform values, you can see a toggle for Mobility. Change this from Static to Moveable, as shown in the following screenshot:

Note

It is good practice to leave comments on the sets of Blueprints as you create them. Comments can help describe what a particular set of Blueprints is intended to accomplish, which can be helpful if you are returning to a Blueprint after some time and need to make sense of your prior work. To leave a comment on a Blueprint, click and drag a selection box around the nodes you want to create a comment around to select them. Then, right-click on one of the selected nodes and select the bottom option, Create Comment from Selection.

Getting relative speed using delta time

To make our speed value relate to direction, we first need to multiply it by delta time. Delta time is based on the fact that the time taken between the frames of the gameplay can differ. By multiplying our speed value to delta seconds, we can ensure that the speed at which our object moves is the same, regardless of the game's frame rate.

To do this, drag the Speed variable onto the event graph and choose Get to create the speed node. Now, right-click on empty graph space and search for delta. Select the Get World Delta Seconds option to place the corresponding node. Finally, drag the output pin from either the delta seconds node or the speed node, and drop it into empty space. Type an asterisk in the search field (Shift + 8 on most computers) and select the Float * Float node. Finally, drag the other output pin onto the remaining input pin of the new multiplication node to multiply these two values, like this:

Changing direction

If you were to compile the Blueprint, save, and play the game now, what would you expect to see? The target cylinder would move according to our speed and direction as soon as the game began. However, since we don't have any instructions that cause the target to stop moving, it would proceed in the same direction for as long as the game runs, even moving through objects and out of the level we created! To address this, we need logic that will change the target's direction periodically. This will result in a target that moves back and forth between two points regularly, much like a shooting gallery target.

To do this, we have to set up two nodes that will set the direction variable we created to two different values. Drag the direction variable into empty grid space and choose the Set option. This will result in a node with X, Y, and Z axis fields. We can use them to change the value of the direction variable to be different from the initial default value that we gave it. We want two of these nodes, so drag the direction variable again into empty space, and then change the Y axis values of the two nodes to 10.0 and -10.0 respectively.

Now we need a way to switch between these two nodes so that the direction repeatedly shifts. The FlipFlop node was created for scenarios where we know we want to alternate between two sets of actions that execute exactly once before switching each time. This fits our use case here, so right-click on empty grid space and search for FlipFlop. Select and place the node. Then connect the A execution pin to one of the direction set node input pins, and the B execution pin to the other.

Finally, we need to ensure that there is some kind of delay between executing the direction shifts. Otherwise, the direction will change for every frame and the object will go nowhere. To do so, drag the input execution pin of the FlipFlop node into empty space and search for the Delay node. This node allows us to set a delay duration, in seconds, that will postpone the following execution commands by that length of time. Place this node before the FlipFlop node and give it a duration of 6 seconds. Placing this Delay node between our Set Actor Transform node and our FlipFlop node will ensure that the direction switch enabled by FlipFlop will occur only every 6 seconds. The final product should look like what is shown in the following screenshot. Once you are done, remember to compile and save the Blueprint.

Testing moving targets

Now that we have our Blueprint updated, we can test to ensure that the CylinderTarget object moves as expected. First, we will have to place the CylinderTarget object in a position that will allow it to move along the Y axis without bumping into other objects. The coordinates I used were 410 on the X axis, 680 on the Y axis, and 180 on the Z axis.

Note that these values will only work relative to the default layout of the First Person template map. If you have made adjustments to your own level, then you can adjust either the speed or the placement of the target in your level, and test until you find a good patrol spot. Click on Play. If the Blueprint is functioning correctly, you will see the cylinder move back and forth between two points at a steady rate.

One of the advantages of using Blueprints is that they create a template of functionality that can be used across multiple objects in a scene. Find CylinderTarget_Blueprint in the Blueprints folder and drag it directly onto 3D Viewport. You will see another cylinder created, which inherits all of the functionality of our original cylinder target. In this way, we can rapidly set up multiple moving targets using the single set of Blueprint logic we created.

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Bernhard Apr 10, 2016

Super Einführung in die Programmierung mit Unreal Blueprints. Wesentlich besser als z.B. "Master the Art of Unreal Engine 4 - Blueprints"

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Harrisoliver May 25, 2019

I was a bit worried it might be out of date, as I'm using it with engine version 4.22.2 and it was written with 4.7, but this has only been an issue on a couple of superficial things so far. Example in chapter 1 when creating a material the book fails to state that you also need to select "used with static lighting" under material details.There's nothing that can't be sorted with a bit of googling and trial and error, and I actually am inclined to recommend the book even more as a result of this as it engages me mentally a bit more and makes for a more rewarding learning experience than simply following the steps listed.I'm very grateful for this book as after nine years out of the loop on Unreal it has been a great resource to get me back into the swing of things. Many thanks.

TB Jul 31, 2018

Ich habe mir dieses Buch als Einstieg ins Visual Scripting für Ego-Shooter zugelegt. Diesen Zweck hat es einwandfrei erfüllt, denn es deckt erfreulicherweise viele Bereiche dafür ab. Natürlich werden da keine hochkomplizierten Mechaniken behandelt, wie man sie aus einem äußerst bekannten Ego-Shooter kennt.Das Buch deckt aber alles ab, um einen lauffähigen kleinen Shooter selbst zusammenzubasteln und überhaupt einen Einstiegspunkt in die Engine zu finden. Die engine-eigene Doku ist für Anfänger beinahe unbrauchbar.

Rob Thompson Aug 26, 2015

This a great book. Unreal Blueprints is quite a topic and getting it into a book with clear examples is exactly what was needed for the Unreal Engine. There are not many books published on Unreal Engine 4 and hopefully this will be the start of many good quality books. The book covers the essentials of Blueprints and makes for an easy read. Follow all the topics and build the content as per the book and you will learn a lot.

cybereality Sep 19, 2019

Blueprints Visual Scripting for Unreal Engine is a great little book. Clocking in at just 190 pages, it is a quick read but packed with practical information. Brenden Sewell does a good job of introducing game development concepts in a series of chapters which build upon the same project, culminating in a nice (if somewhat simple) demo at the end.Inside this book, the author discusses the basics of using Blueprints, customizing the character controller, creating UI elements, working with branching and conditional statements, simple enemy AI, implementing game states, as well as building and publishing your game. Certainly not an exhaustive list, but a good range of popular topics you will need to make a game with Unreal Engine.I found the chapters on AI to be especially compelling. They were clearly explained and very functional. The way the chapters all build upon one another was also a plus, and made the learning practical.Overall an enjoyable book and a good introduction to using Blueprints visual scripting in UE4. The text uses the Unreal default art assets, so the demo you create is not particularly fresh in terms of the design, but if you want to learn visual coding, this is a great place to start.

Blueprints Visual Scripting for Unreal engine: Build professional 3D games with Unreal Engine 4's Visual Scripting system

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Blueprints Visual Scripting for Unreal engine

Chapter 1. Object Interaction with Blueprints

Creating a project and the first level

Creating the project

Adding objects to our level

Exploring materials

Creating materials

Material properties and Blueprint nodes

Tip

Adding substance to our material

Creating our first Blueprint

Exploring the Event Graph panel

Adding movement

Changing actor mobility and collision

Note

Getting relative speed using delta time

Changing direction

Testing moving targets

Summary

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Blueprints Visual Scripting for Unreal engine: Build professional 3D games with Unreal Engine 4's Visual Scripting system

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Creating a project and the first level

Creating the project

Adding objects to our level

Exploring materials

Creating materials

Material properties and Blueprint nodes

Tip

Adding substance to our material

Creating our first Blueprint

Exploring the Event Graph panel

Adding movement

Changing actor mobility and collision

Note

Getting relative speed using delta time

Changing direction

Testing moving targets

Summary

Page 1 of 8

Key benefits

Description

Who is this book for?

What you will learn

Product Details

What do you get with eBook?

Contact Details

Billing Address

Product Details

Packt Subscriptions

Frequently bought together

Table of Contents

Recommendations for you

Customer reviews

Filter reviews by

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FAQs

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