Appendix A: Converting 3D Model Files

To display virtual objects in an augmented reality app, you have several options. First, you can create virtual objects out of common geometric shapes (box, sphere, torus, pyramid, etc.). The problem with this approach is that it’s time-consuming and clumsy. Trying to create sophisticated images like a dinosaur, medieval castle, or jungle river can only create chunky figures that don’t look realistic.

A second approach is to draw the virtual object yourself using a 3D modeling program. While this can create more realistic and sophisticated images, it’s beyond the skill of all but the most experienced graphic artists.

A third solution is to simply download and use a 3D model that someone else has already created. Several sites that offer 3D models for free (or for a fee) include:

• TurboSquid ( www.turbosquid.com )

• Free3D ( https://free3d.com )

• Poly ( https://poly.google.com )

However, ARKit can only accept two types of files: SceneKit (.scn) and COLLADA (.dae) . You won’t find too many SceneKit (.scn) images available, but you will find many COLLADA (.dae) images available. Of course, many 3D models are stored in other file formats so if you want to use them, you’ll have to convert them into a COLLADA (.dae) file first. Then you can use them with ARKit or convert them to a SceneKit (.scn) file as well.

Converting COLLADA (.dae) to SceneKit (.scn)

If you have a COLLADA (.dae) file, you can drag and drop it into the Navigator pane of Xcode and then use the file with no further need of conversion. However, if you want to convert a COLLADA (.dae) file into a SceneKit (.scn) file , follow these steps:

1. 1.

   Drag and drop the COLLADA (.dae) file into the Navigator pane of Xcode.

    
2. 2.

   Choose Editor ➤ Convert to SceneKit scene file format (.scn), as shown in Figure A-1 . A dialog box appears, letting you know that SceneKit (.scn) files may not be compatible with some applications.

    

Figure A-1

The Editor menu displays the Convert to SceneKit Scene File Format command

1. 3.

   Click the Convert button. Xcode converts your COLLADA (.dae) file into a SceneKit (.scn) file .

    

Convert 3D Models into a COLLADA (.dae) File

Since there are many 3D models available that are not saved in either the SceneKit (.scn) or COLLADA (.dae) file format, you won’t be able to use those files unless you convert them into a COLLADA (.dae) file first. While there are numerous 3D modeling programs that offer the capability of importing a 3D model and exporting it as a COLLADA (.dae) file, most of these programs are expensive.

For a free option, download Blender ( www.blender.org ), which is an open source 3D modeling program that runs on Windows, Linux, and MacOS. After you download and install Blender on your computer, you’ll be able to use Blender to import 3D models stored in other file formats and export them as COLLADA (.dae) files.

To use Blender to convert 3D models into COLLADA (.dae) files, follow these steps:

1. 1.

   Start Blender . Blender will create a 3D model that includes a camera, cube, and lamp, which appear in both the 3D model and as names listed in the upper-right corner of the Blender window, as shown in Figure A-2 .

    

Figure A-2

Blender creates a basic 3D model that includes a camera, cube, and lamp

1. 2.

   Right-click on the Camera, Cube, and Lamp listed in the upper-right corner of the Blender window . A popup menu appears, as shown in Figure A-3 .

    

Figure A-3

The popup menu displays the Delete command

1. 3.

   Choose Delete.

    
2. 4.

   Repeat Steps 2-3 until you’ve deleted the Camera, Cube, and Lamp.

    
3. 5.

   Choose File ➤ Import. Blender displays a menu of all 3D model file formats it can import, as shown in Figure A-4 .

    

Figure A-4

The File ➤ Import menu displays all 3D model file formats Blender can open

1. 6.

   Choose the 3D file format of the 3D model that you want to open, such as 3D Studio (.3ds) or Wavefront (.obj). Blender displays a list of folders.

    
2. 7.

   Navigate to the folder that contains the 3D model you want to import.

    
3. 8.

   Click on the 3D model you want to import and click the Import button in the upper-right corner of the Blender window, as shown in Figure A-5 .

    

Figure A-5

Importing a 3D model file

1. 9.

   Choose File ➤ Export ➤ COLLADA (default) (.dae). Blender displays all the folders on your computer.

    
2. 10.

   Choose a folder to store your COLLADA (.dae) file.

    
3. 11.

   Click on the untitled.dae default filename and give your file a more descriptive filename.

    
4. 12.

   Click the Export button in the upper-right corner of the Blender window. Blender stores your COLLADA (.dae) file in your chosen folder. Now you can drag and drop this COLLADA (.dae) file into the Navigator pane of Xcode.

    

Appendix B: Creating Virtual Objects Visually

There are often two ways to accomplish almost everything in Xcode. One way is programmatically, where you write Swift code to do something. The second way is visually, where you drag and drop items to do something.

When creating virtual objects to display in an augmented reality view , this book mostly focused on creating virtual objects programmatically using Swift code similar to the following:

let boxNode = SCNNode()

boxNode.geometry = SCNBox(width: 0.08, height: 0.08, length: 0.08, chamferRadius: 0)

boxNode.geometry?.firstMaterial?.diffuse.contents = UIColor.green

boxNode.position = SCNVector3(x, y, z)

sceneView.scene.rootNode.addChildNode(boxNode)

While writing Swift code to create virtual objects is fine, it can get cumbersome when creating multiple virtual objects. As an alternative to writing so much Swift code to create virtual objects, Xcode gives you the option of adding virtual objects and storing them in a SceneKit (.scn) file. Then all you need to do is add and arrange as many virtual objects as you wish and store them as a SceneKit (.scn) file . When you load this SceneKit (.scn) file in an augmented reality view, all the virtual objects appear without you having to define each one individually.

Creating a SceneKit Assets Folder

The first step to using a SceneKit (.scn) file is to create an assets folder by following these steps:

1. 1.

   Choose File ➤ New ➤ File. A template window appears.

    
2. 2.

   Scroll down to the Resource category and click the SceneKit Catalog icon, as shown in Figure B-1 .

    

Figure B-1

Creating a SceneKit Asset Catalog folder

1. 3.

   Click the Next button. Xcode displays a Save As dialog.

    
2. 4.

   Click the Create button. Xcode creates a SceneKit Asset Catalog.scnassets folder in the Navigator pane.

    
3. 5.

   Click on the SceneKit Asset Catalog.scnassets folder and press Return. Edit this name to something shorter, such as scene.scnassets.

    

Creating a SceneKit (.scn) File

Once you’ve created a SceneKit Assets folder, you need to create a SceneKit (.scn) file to store in this SceneKit Assets folder. To create a SceneKit (.scn) file, follow these steps:

1. 1.

   Choose File ➤ New ➤ File. A template window appears.

    
2. 2.

   Scroll down to the Resource category and click the SceneKit Scene File icon , as shown in Figure B-2 .

    

Figure B-2

Creating a SceneKit Scene File

1. 3.

   Click the Next button. Xcode displays a Save As dialog.

    
2. 4.

   Click the Create button. Xcode creates a SceneKit Scene.scn file in the Navigator pane.

    
3. 5.

   Click on the SceneKit Scene.scn file and press Return. Now you can edit this filename to something more descriptive if you want.

    
4. 6.

   Drag and drop this SceneKit Scene.scn file into the SceneKit Assets folder. The SceneKit Scene.scn file is inside the folder when it appears indented underneath the SceneKit Assets folder , as shown in Figure B-3 .

    

Figure B-3

Placing a SceneKit file inside the SceneKit assets folder

Adding Virtual Objects to a SceneKit (.scn) File

After you’ve created a SceneKit (.scn) file and stored it into your SceneKit Assets folder, the next step is to add virtual objects to that SceneKit (.scn) file through the Object Library by following these steps:

1. 1.

   Click on the SceneKit (.scn) file stored inside your SceneKit assets folder. Xcode displays a blank scene.

    
2. 2.

   Click the Object Library icon to display the Object Library window.

    
3. 3.

   Scroll down to find the different geometric shapes available such as Box, Cylinder, or Pyramid, as shown in Figure B-4 .

    

Figure B-4

The Object Library window

1. 4.

   Drag and drop one or more geometric shapes, such as a Box, Sphere, or Torus from the Object Library window on to the SceneKit, as shown in Figure B-5 .

    

Figure B-5

Placing virtual objects on to the SceneKit (.scn) file

Customizing Virtual Objects

Once you’ve placed one or more virtual objects in a SceneKit (.scn) file, you can customize that virtual object through one of the following inspectors :

• Node inspector—Defines the position, scale, and Euler angle

• Attributes inspector—Defines the dimensions

• Materials inspector—Defines the outer appearance

• Physics inspector—Defines how the virtual object responds to physics

• Scene inspector—Defines the background illumination

To view an inspector pane for a virtual object, follow these steps:

1. 1.

   Click on the virtual object that you want to modify.

    
2. 2.

   Choose View ➤ Inspectors and then choose the inspector pane you want to view, such as Materials or Node, or click on the appropriate icon at the top of the inspector pane, as shown in Figure B-6 . Each time you open a different inspector pane, you’ll be able to modify various properties of your selected virtual object.

    

Figure B-6

The inspector pane for a virtual object

Linking Virtual Objects

Each time you drag and drop a virtual object into a SceneKit (.scn) file, it acts independently of any other virtual objects in that same SceneKit file. However, you may want to keep two or more virtual objects linked together. That way if you modify the position of one virtual object, all linked virtual objects will move to maintain their relative position to the other virtual objects.

To link one virtual object with another, follow these steps:

1. 1.

   Click on the Show/Hide Scene Graph View icon to open the Scene Graph View . The Scene Graph View lists all the names of the virtual objects displayed in a SceneKit (.scn) file such as box or cone, as shown in Figure B-7 .

    

Figure B-7

The Show/Hide Scene Graph View icon

1. 2.

   Click on the virtual object name in the Scene Graph View that you want to link to another virtual object.

    
2. 3.

   Drag the virtual object until it appears underneath under another virtual object name. Xcode displays a blue horizontal line.

    
3. 4.

   Drag the virtual object to the right underneath the name of another virtual object. The blue horizontal line appears indented, as shown in Figure B-8 .

    

Figure B-8

Indenting a virtual object name under another one

1. 5.

   Release the left mouse button. Xcode now displays the virtual object name indented underneath the other virtual object name, which displays a gray disclosure triangle that you can click to hide or show all linked virtual objects, as shown in Figure B-9 .

    

Figure B-9

The Scene Graph View displays linked virtual objects by indenting

Displaying a SceneKit (.scn) File in Augmented Reality

After you’ve modified any virtual objects by defining their position, size, scale, or Euler rotational angle, you can finally display your entire SceneKit (.scn) file in an augmented reality view . First, you must know the folder name (such as scene.scnassets) and the SceneKit filename (such as myScene.scn ).

Then you can create a variable to hold your scene such as:

let item = SCNScene(named: "scene.scnassets/myScene.scn")!

This code assumes the SceneKit assets folder is called scene.scnassets and that the SceneKit (.scn) file is called myScene.scn .

Now you can add this item to your augmented reality view like this:

sceneView.scene = item

Assuming your user interface contains an ARKit SceneKit View and its IBOutlet is defined as sceneView, displaying a SceneKit (.scn) file can be as simple as this entire ViewController.swift file:

import UIKit

import SceneKit

import ARKit

class ViewController: UIViewController, ARSCNViewDelegate {

     @IBOutlet var sceneView: ARSCNView!

     let configuration = ARWorldTrackingConfiguration()

     override func viewDidLoad() {

         super .viewDidLoad()

         // Do any additional setup after loading the view, typically from a nib.

        sceneView.debugOptions = [ARSCNDebugOptions.showWorldOrigin, ARSCNDebugOptions.showFeaturePoints]

        sceneView.delegate = self

         let item = SCNScene(named: "scene.scnassets/myScene.scn")!

        sceneView.scene = item

        sceneView.session.run(configuration)

    }

}

Index

A, B

Aiming point

ARKit

Apple’s free Xcode compiler

augmented reality app

iOS device’s camera

Macintosh

options

SceneKit

target

virtual airplane

Xcode project template

COLLADA

definition

IKEA, Metaio’s technology

iOS 12

iPhone 6s/6s Plus or iPad Pro

Macintosh

Objective-C

simulator program

Swift

Swift code ( see Swift code)

Xcode

ARKit coordinate system

ARKit SceneKit View (ARSCNView)

Augmented reality (AR)

Apple

Akonia Holographics

ARKit ( see ARKit)

Flyby Media’s technology

IKEA Place app

SensoMotoric instruments

VRvana

ARSCNView object

Berlin Wall app

camera privacy setting

device capabilities setting

Disney corporation

Ferrari, app

HUD

hunting scope

IKEA, Metaio’s technology

Info.plist file

iOS devices

high resolution cameras

high-resolution displays

motion tracking

powerful processors

measuring cup

Pepsi promotional prank

Pokemon GO

TAC

user interface, ARSCNView object

C

Clear button

clearMap function

creation

distinctive flat surface

persistence icon

thumbnail images

COLLAborative Design Activity (COLLADA)

COLLADA (.dae) to SceneKit (.scn) convertion

Collision, virtual objects

addTargets function

code testing

detection

enumeration structure

switch statement

tapResponse function

ViewController.swift file

ViewController.swift file

Color light

D

didUpdate renderer function

Displaying planes

creation

horizontal plane

navigator pane

ViewController.swift file

Displaying text

augmented reality view

extrusion depth

material class

node’s geometry, define

orange text

3D models into COLLADA (.dae)

Dynamic virtual objects

E, F

EulerAngles

G

Geometric shapes

augmented reality view

box display

color, define

display box

augmented reality

chamferRadius

dimensions

geometric objects, creation

rounded edges

ViewController.swift file

drawing

adding multiple addLine commands

addLine command

BezierPath object

extrusion depth

plane.addLine command

wedge shape, creation

x and y coordinates

yellow plane, creation

radius, define

sphere creation

texture images, adding

augmented reality view

displaying

earth.jpg

material

pyramid and wood texture

searching in internet

ViewController.swift file

Xcode project

transparency change

virtual objects

Gestures

GLKit framework

GLKMathDegreesToRadians function

guard statement

H

handleLongPress function

handleTap function

Heads-up display (HUD)

hitTest function

hitTest method

Horizontal planes

addObject function

Info.plist file

orange pyramids

Swift code

tap gesture recognizer

ViewController.swift file

worldTransform matrix

Xcode, creation

I, J

IBAction method

IBOutlets

Image detection

display information

AR Resources folder

planeNode

SCNNode

yellow plane

displaying virtual objects

nodeFor renderer function

rootnode name

ship.scn

ViewController.swift file

Info.plist file

Swift code

switch statement

Target Membership check box

video ( see Video, display)

ViewController.swift file

Xcode, creation

Image recognition

ARKit

AR Resources

guard statement

multiple images

storing

ViewController.swift file

width and height of item

yellow plane

Image tracking

ARKit recognizer

AR Resources

guard statement

Info.plist file

Moving Text

Swift code

three-dimensional object

ViewController.swift file

Xcode, creation

initialWorldMap property

Instrument panel

K

Kinematic virtual objects

L

Lights

colors

designing, user interface

directional light

Info.plist file, camera access

intensity

defining value, slider

lightOn function

Main.storyboard user interface

omni light

showLight.position command

temperature

defining values

UISlider

types

UIButtons

background color

width and height

ViewController.swift file

colorButton IBAction method

IBOutlet

intensityChange

intensityChange IBAction method

lightOn function

temperatureChange IBAction method

temperature UISlider

viewDidLoad function

viewWillAppear function

virtual objects

world origin (0, 0)

loadMap() function

Long press gestures

handleLongPress

create

hitTest function

ViewController.swift file

properties

M, N

Measuring app

Info.plist file

popup window

tap gesture recognizer

ViewController.swift file

ARSCNView

UILabel

UILabel, alignment

Xcode, creation

Multiple images

AR Resources folder

ImageDetection project

nodeFor renderer function

ViewController.swift file

O

Object detection

ARKit recognizer

AR Resources folder

Info.plist file

Swift code

ViewController.swift file

Xcode, creation

Object Library window

Occlusion

detectPlane function

Info.plist file

invisible horizontal plane

real horizontal surface

Swift code

tap gesture

tapResponse function

testing

ViewController.swift file

Xcode, creation

P, Q

Pan gesture recognizers

ARSCNView

Document Outline

IBAction method

Object Library

Run button

Stop button

translation movement

UIPanGestureRecognizer

virtual plane

Xcode, types

Pan gestures

create Pan Gesture Recognizer

parts of

translation property

ViewController.swift code

Persistence

didAdd renderer function

Info.plist file

Swift code

ViewController.swift file

viewDidLoad function

viewWillDisappear function

Xcode, creation

Pinch and rotation gestures

add recognizer

IBAction method

Object Library window

ViewController.swift file

Pinch gesture recognizer

Connection popup menu

Document Outline

IBAction method

Main.storyboard file

Object Library

Run button

Stop button

UIPinchGestureRecognizer

ViewController.swift file

Pinch touch gesture

hitTest method

IBAction method

pinchGesture function

states

virtual plane, scaling

Planes

detection

displaying ( see Displaying planes)

horizontal ( see Horizontal planes)

Info.plist file

iOS device

renderer function

user interface

vertical planes ( see Vertical planes, detection)

ViewController.swift file

Xcode, creation

Positioning virtual objects

geometric shapes

augmented reality view

cylinders

Macintosh, USB cable

radius

relative positioning

rootnode

showShape

snowman

spheres

ViewController.swift

relative positions

ARSCNView

augmented reality view

constraints

coordinates

distance calculation

Info.plist

rootnode

SCNVector3

showShape

Swift code

ViewController.swift

viewDidLoad function

viewWillAppear function

Xcode project

trial and error

Pythagorean’s theorem

R

Relational object rotation

green pyramid

function

relative positioning

showShape function

Rotating objects

Euler angles

creating Xcode project

GLKMathDegreesToRadians

green pyramid

modify Info.plist

modify ViewController.swift file

SCNVector3 values

user interface

user interface to Swift code

ViewController.swift file

Rotation touch gesture

currentAngleZ variables

IBAction method

recognizer

virtual plane

Ruler app

defining points

hitTestResults constant

tapResponse function

worldTransform property

distance between virtual objects

append method

displayText function

measuring real world objects

realPoints array

ViewController.swift file

hitTest method

ViewController.swift file

S

saveMap() function

Scanning object

install

steps

SceneKit (.scn) file

assests folder

augmented reality view

creation

assets folder

scene file icon

inspector pane

inspectors

link virtual objects

indenting

scene graph view

object library

Screen Edge Pan Gesture Recognizer

showShape() function

Single View App template

ARKit Scene View

augmented reality app

.dae COLLADA files

ARKit SceneKit View

diffuse popup menu

3D images

Macintosh

scene graph view

scnassets

.scn file

show material inspector

texture file

IBOutlet

ARKit SceneKit View

assistant editor icon

defining name

Object Library window

ViewController.swift file

viewDidLoad function

Info.plist file

iOS device’s camera

Main.storyboard file

privacy–camera usage description

sceneView variable

storyboard screen

ViewController.swift file

Spotlights

adding constraints

ARKit and SceneKit

axes of rotation

designing, user interface

eulerAngles property

Info.plist file, camera access

iOS device

location and angle, define

Main.storyboard user interface

position and angle

UISlider

ViewController.swift file

IBOutlet

lightOn function

pitchChange IBAction method

rollChange IBAction method

viewDidLoad function

viewWillAppear function

yawChange IBAction method

virtual object

world origin (0, 0)

yellow plane

z-axis

SpriteKit

Static virtual objects

Swift code

ARKit

ARSCNViewDelegate

3D image

IBOutlet

SceneKit

sceneView

ship.scn file

texture.png file

UIKit

ViewController.swift file

viewDidLoad method

viewWillAppear method

Swipe gestures

handleSwipe function

hitTest method

numberOfTouchesRequired property

UISwipeGestureRecognizer

T, U

Tactical augmented reality (TAC)

Tap gesture recognizer

tapResponse function

Touch gestures

ARSCNView

create Xcode

identifying

hitTest function

ViewController.swift file

Info.plist file

pan gesture ( see Pan gesture recognizers)

pinch gesture ( see Pinch touch gesture)

pinching motion

recognizer

detection

handleTap function

UITapGestureRecognizer

rotation gesture ( see Rotation touch gesture)

user interface to Swift code

ViewController.swift file

Xcode, creation

Two-finger gesture

V

Vertical planes, detection

addObject function

image painting

tapResponse function

viewDidLoad function

Video, display

AR Resources folder

QuickTime Player program

SKVideoNode

ViewController.swift file

viewDidLoad function

viewWillAppear function

Virtual objects

augmented reality view

collision ( see Collision, virtual objects)

displayPlane function

drawing

aiming point

camera information

DispatchQueue

enumerateChildNodes

frames per second

guard statement

Info.plist file

renderer function

rootnode

Swift code

UIButton, background color

UISwitch state

user interface, ARSCNView

ViewController.swift file

willRenderScene function

Xcode, creation

dynamic

force

applyForce method

ARKit SceneKit View

camera’s location

camera’s position and orientation

constraints

.dynamic

Info.plist file

projectile

tap gesture

tapResponse function

user interface, Swift code

ViewController.swift file

Xcode project

Info.plist file

kinematic

physical characteristics

SceneKit (.scn) file

sphere fall

static

Swift code

ViewController.swift file

Xcode

Virtual reality (VR)

drawback

headsets

Visual-inertial odometry

W, X, Y, Z

World map

loading

saving

World origin

displaying, augmented reality app

active scheme popup menu

ARKit SceneKit View

ARSCNView

coordinates

Info.plist file, camera access

Main.storyboard file

steps

ViewController.swift file

Xcode

yellow sphere

resetting, coordinates

IBAction method, creation

IBAction resetButton function

IBOutlet line

UIButton adding, user interface

UIButton, creation

ViewController.swift file

yellow sphere

Add button

addButton IBAction method

displaying multiple

IBAction method

IBOutlet creation, slider

minimum and maximum values, slider

modifying, slider properties

redesigning user interface

resetButton function

SCNNode

showShape() function

slider values, define

UISliders

ViewController.swift file

World tracking