How to Make a VR Game With Unity and Google Cardboard
Google Cardboard is a new API for creating virtual reality games with a DIY headset. In this tutorial, you’ll use it to kill blobs with throwing stars! By Todd Kerpelman.
Update note: This tutorial was updated in May 2016 for the new Google Cardboard SDK, which is now called the Google VR SDK. If you completed this tutorial previously, and want to migrate over to the new SDK, refer to the Google VR release notes.
Welcome… to the THIRD DIMENSION!
Transform a boring ol’ top-down game (top) to an exciting VR game (bottom)!
It’s probably safe to say that everybody has been waiting for virtual reality experiences since that classic of modern cinema, “Lawnmower Man”, promised us a delightful future of, um, virtual reality where we could all have telepathic powers. Or something like that.
In this tutorial, you’ll help humanity prepare for its future of telepathic abilities and virtual reality by learning to take a simple Unity game and make it work as a VR experience using Google Cardboard. You’ll find out how to:
- Integrate a VR camera into your projects
- Modify UI elements so that they work in VR mode
- Make buttons selectable in VR mode
- Switch programmatically between regular and VR mode at run time
Note: At the time of writing, mind control and becoming a super human through VR is not a viable technology, in spite of what “Lawnmower Man” showed us. So, until Apple has a mind control API, just stick with mastering its precursors.
What is Google Cardboard?
In theory, creating a VR experience is straightforward. Instead of displaying your world as a single image on screen, you display two images.
They come from two cameras placed a few inches apart, and the user views the image from the left camera with the left eye and vice versa, creating the appearance of depth.
Additionally, with some judicious use of motion sensors, you can detect the direction the user is facing. Combine that with the 3D world you’ve created, and you’ve got yourself an immersive experience.
In practice, it takes some pretty sophisticated hardware to display two images on a high-definition screen, along with tracking the user’s head, and putting that all into a device small and light enough that it doesn’t hurt your neck.
Well, it turns out that such highly advanced technology is probably in your pocket or sitting within arm’s reach. It’s in almost every smartphone, and that’s the idea behind Cardboard; it can take the display and sensors in your phone and turn them into a respectable VR device, using just some cardboard and plastic lenses.
Getting Started
Note: You’re going to be working with the Unity GUI quite a bit. If you’ve never worked with it before, you might want to take a look at our Unity GUI tutorial.
To get started making your own VR game with Google Cardboard, you’re going to need the following:
- Unity Personal Edition, version 5.x
- A smartphone, either an iPhone 5 or later or an Android phone running Jelly Bean or later on which to test. By the way, this tutorial will assume you’re working on an iPhone.
- Oh, yeah, and a Cardboard unit.
Wait… How Do I Get a Cardboard Unit?
Don’t have a Cardboard unit? Your best bet is to order it from any of the vendors listed here. It should cost you around $20 or $30, plus shipping. If you’re feeling like a DIY superstar, you could even make your own.
When buying a Cardboard device, look for ones that mention “V2” or “Cardboard 2.0”, because they fit a larger variety of phones, including big phones like the iPhone 6+. They also support user input with a button that’s covered in conductive metal tape that taps the phone’s screen when you press down on it.
Can I Do this Tutorial Without a Cardboard Unit?
Well, kinda. You’ll be able to run your game on your phone, and it’ll look like this.
You can approximate a 3D experience if you stare past the screen just right while playing. If you move your phone around, you’ll be able to control it just as though your phone were strapped to your head, and you can simulate clicks by tapping the screen.
Although you could play the game and get a sense of what it would be like if you were viewing it through a VR headset, it doesn’t mean you should. It’s kind of like the difference between eating chocolate and listening to a friend describe to you how chocolate tastes. Sure, you’ll get the general idea, but it just won’t be the same.
Long story short: if you’re too impatient to wait for that Cardboard unit to arrive, you can still learn from this tutorial, but you’ll get a lot more out of it with the right equipment.
The Sample Game — Ninja Attack is Back!
Take a moment to try out your sample game. Download and unzip the Unity starter project.
Next, start up Unity. From the welcome screen, select Open and then the StarterNinja folder to open the NinjaAttack project.
In the Project Browser, double-click MainScene in Assets. Then give the game a try by pressing Play.
You’re the ninja on the left. As monsters make their way across the screen, click anywhere on the screen to launch a ninja star and take ’em out! Take out 20 monsters and you win, but if a monster reaches the red zone on the left, you lose.
The blobs are at it again. Will they ever learn?
Does this game look familiar? For those of you who are long-time readers of raywenderlich.com, you might recognize this as the same ninja game from your SpriteKit and Cocos2D tutorials. But this time it’s rendered in glorious 3D!
Not that you’ll really notice most of that glorious dimension though. The entire game is top-down. It almost feels like a waste rendering all these polygons. Now you’re seeing why this game is the perfect candidate for VR.