1.
Coding a VR
Application
in Android
A Practical Guide

2.
Virtual Reality @
CommonFloor

3.
Virtual Reality @
CommonFloor

4.
Contents
❖ Introduction to Google Cardboard SDK for Android
❖ Requirement of separate SDK for VR ?
❖ Getting Started with First Android Application for VR
❖ Setup of coding environment
❖ Overview of code

5.
Intro to Google Cardboard
SDK
❖ Cardboard SDK for Android enables developers familiar with OpenGL to
quickly start creating VR applications.
❖ The toolkit simplifies many common VR development tasks, including:
❖ Lens distortion correction.
❖ Head tracking.
❖ 3D calibration.
❖ Side-by-side rendering.
❖ Stereo geometry configuration.
❖ User input event handling.

6.
Setup of Coding Environment
❖ Building the demo app requires:
❖ Android Studio 1.0 or higher
❖ https://developer.android.com/sdk/index.html
❖ Version 19 of the Android SDK
❖ A physical Android device running Android 16 (Jelly
Bean) or higher

7.
Lets start coding
❖ Main components of Android VR Application
❖ Manifest file
❖ Cardboard Activity
❖ Custom Renderer
❖ Content Model

8.
Android Manifest File
Need to specify following permissions in manifest file
❖ NFC — Input Mechanism used by cardboard trigger button
<uses-permission android:name="android.permission.NFC" />
❖ Vibration Sensor — Haptic Feedback mechanism for certain events in Application
<uses-permission android:name="android.permission.VIBRATE" />
❖ Read and write to external storage
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
❖ Specify minimum and target SDK version
<uses-sdk android:minSdkVersion="16" android:targetSdkVersion="19"/>
❖ Specify the OpenGL ES version that device must support to run the application
<uses-feature android:glEsVersion="0x00020000" android:required="true" />

9.
Cardboard Activity
❖ Starting point for coding a cardboard app.
❖ Base activity that provides easy integration with
Cardboard devices.
❖ Exposes events to interact with Cardboards.
❖ Uses sticky immersive mode, in which the system UI is
hidden, and the content takes up the whole screen.

10.
Custom Renderer
❖ Custom Renderer for CardboardView
❖ Implements the CardboardView.StereoRenderer interface
❖ Delegates all stereoscopic rendering details to the view
❖ All stereoscopic rendering and distortion correction details are abstracted from the renderer and managed
internally by the view
❖ Overrides the following important methods
// Prepares OpenGL ES before we draw a frame.
// @param headTransform The head transformation in the new frame.
@Override
public void onNewFrame(HeadTransform headTransform) {
// Called when a new frame is about to be drawn.
// Any per-frame operations not specific to a single view should happen here.
}
@Override
public void onDrawEye(Eye eye) {
// Draw the frames for each eye
}

11.
Custom Renderer
OnDrawEye Function
// Draws a frame for an eye.
// @param eye The eye to render. Includes all required transformations.
@Override
public void onDrawEye(Eye eye) {
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT);
. . .
// Apply the eye transformation to the camera.
Matrix.multiplyMM(mView, 0, eye.getEyeView(), 0, mCamera, 0);
// Set the position of the light
Matrix.multiplyMV(mLightPosInEyeSpace, 0, mView, 0, LIGHT_POS_IN_WORLD_SPACE, 0);
// Build the ModelView and ModelViewProjection matrices
// for calculating cube position and light.
float[] perspective = eye.getPerspective(Z_NEAR, Z_FAR);
Matrix.multiplyMM(mModelView, 0, mView, 0, mModelCube, 0);
Matrix.multiplyMM(mModelViewProjection, 0, perspective, 0, mModelView, 0);
drawCube();
// Draw rest of the scene.
. . .
}

12.
Content for VR - 3D Models
❖ Consists of any 3D model that we want to render in our application
❖ Can be a simple model like a sphere or cube
❖ Can be complex models of house, players etc to create a real 3D
scene.

13.
Wrap it up and Lets Code !!!
3D
Assets
Carboard.jar
Google Cardboard
Android Application
Redistributable
APK
Cardboard SDK
Compatible
Android Phone
+ =
=
Android
Code +