Coding a VR Applicationin Android

A Practical Guide

Virtual Reality @

CommonFloor

Virtual Reality @

CommonFloor

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

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.

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

Lets start coding

❖ Main components of Android VR Application❖ Manifest file❖ Cardboard Activity❖ Custom Renderer❖ Content Model

Android Manifest FileNeed 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" />

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.

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.}

@Overridepublic void onDrawEye(Eye eye) { // Draw the frames for each eye

}

Custom RendererOnDrawEye Function// Draws a frame for an eye.

// @param eye The eye to render. Includes all required transformations.@Overridepublic 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.

. . .

}

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.

Wrap it up and Lets Code !!!

3DAssets Carboard.jar Google Cardboard

Android Application

Redistributable APK

Cardboard SDK Compatible

Android Phone

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