This document discusses programming virtual reality applications for Google Cardboard using Android. It provides an overview of Cardboard, how to program for it using the available SDKs and libraries, and how to expand upon the basic Google Cardboard demo application. The document also proposes using a content management system to dynamically manage VR content so it can be changed without a new app release. This would allow non-technical users to update textures, models, and other assets in the VR experience.

1. Mario Bodemann
Android and Java Evangelist
@mariobodemann
@contentful
Virtual Reality in Android

2. API driven CMS, emphasis on content creation and delivery.

3. Virtual Reality in Android
Using Cardboard

4. What is
Cardboard?
● Easy to produce
● Available from
different companies
and in different
shapes
● can have a
button/lever/hole for
interaction
● only needs a smart
phone (Android/ios)
and an App

5. How does it work?
● Use 3D data and
movement to draw
two images: left and
right eye
● Distort images for
lenses
● Combine image to
scene in brain

6. Programming Cardboard

7. How do I program Cardboard?
https://developers.google.com/cardboard/android/
● SDKs available for
● Java
○ OpenGL
○ Pure Android
● Unity Plugin
○ Unity Engine (C# /JS)
○ Platform independent
○ No reliable linux development available

8. ● Demo app
○ Find a box and
press the button
○ On github
● Library
○ jar distributed
with demo
repository
○ no maven
repository
How To: Android
Demo
https://github.com/googlesamples/cardboard-java

9. Setup of the demo
Activity
Model
Repository
OpenGL
Interaction
● All code in one
Activity
○ OpenGL code
○ Model creation
● Hard to expand on

10. Expanding on the demo

11. ● App using above
code as base
● Expanding it to new
use cases
● Having fun exploring
Contentful
Cardboard Idea
https://github.com/contentful-labs/contentful-cardboard
https://play.google.com/apps/testing/com.contentful.cardboard

12. MVPR
Presenter
Model
Repository
OpenGL
Interaction
Interactor
Activity
(View)
VR
Renderer
● Split Activity into
several parts
● Improve modularity
● Improve testability
● Improve readability
● Improve line number
count ;)

13. Interactor
● Repository
abstraction
● Uses registered
Listener to inform
Presenter
● Live time of the
Presenter
public interface Interactor {
interface Listener {
void onModelReceived(ProtoModel model);
void onError(Throwable throwable);
}
void setListener(Listener listener);
void requestModels();
}

14. Presenter
● Coordinates
Interactor and View
● Enriches data from
Interactor
● Tells View to update
its models
public class Presenter implements
Interactor.Listener {
// … setup
private int received = 0;
@Override public void onModelReceived
(ProtoModel model) {
model.position[0] += received * 4.0f;
received++;
view.addProtoModel(model);
}

15. View
● Connects Renderer
and Presenter
● Takes models and
enqueues them in
the renderer
● Startup point for
Android app
● Deals with
interaction
public class MainActivity
extends CardboardActivity
implements CardboardView.StereoRenderer,
View {
@Override
public void onCreate(…) {
renderer = new CardboardRenderer(
getApplicationContext());
presenter = new Presenter(
new ContentfulInteractor(this));
presenter.bind(this);
}
@Override
public void onCardboardTrigger() {
vibrator.vibrate(25);
userInteracted();

16. View (cont.)
● Listens to Cardboard
Library callbacks
● For setup of a frame
● And rendering every
eye, redirecting it to
the renderer
@Override
public void onSurfaceCreated(…) {
renderer.surfaceCreated();
}
@Override
public void onNewFrame(
HeadTransform headTransform) {
renderer.prepare();
}
@Override
public void onDrawEye(Eye eye) {
float[] perspective = eye.getPerspective
(Z_NEAR, Z_FAR);
float[] eyeView = eye.getEyeView();
renderer.render(perspective, eyeView);
}

17. Renderer public class CardboardRenderer implements
Renderer {
@Override public void surfaceCreated() {
addFloorAndCeiling();
}
@Override public void prepare() {
addPendingModels();
glEnable(GL_DEPTH_TEST);
glEnable(GL_BLEND);
// … More gl* calls
}
● Abstracts from
OpenGL rendering
● Generates OpenGL
GPU Models
● Listens to View

18. @Override
public void render(float[] perspective,
float[] eyeView) {
multiplyMM(view, 0, eyeView, 0, camera,
0);
for (final Model model :
backgroundModels) {
renderModel(perspective, model);
}
for (final Model model :
foregroundModels) {
renderModel(perspective, model);
}
}
Renderer (cont.)
● Render all models
added
● Starting with
background objects,
since foreground
objects contain
transparency

19. Advantage of new system

20. Sample Challenge: How to change a texture?
● Change file
● Rerun tooling
● Re releasing new version in store
● Convince user to update
● Need technical person
● Potentially through several iterations

21. Purposal:
Using A CMS
● Change a asset
online
● Restart app to resync
data (done at
startup?)
● User only needs
network
● Can be done by non
technical person

22. Using A CMS
● Everything except for
the grid comes from
CMS
● Changing it with drag
and drop
● Changing VR content
from outside

23. Future

24. ● Unit tests?
● Provide different Renderer VR/classic/engine code?
● CMS for Shader?
● A/B testing of in assets?
● Your ideas?
Future

25. Recap

26. Recap
● Cardboard is relatively easy to program and use
● Expanding from Google Demo is the key to success
● Using a CMS for VR

27. Questions and Answers