Google DayDream-Android篇

官方文档

一、Google VR SDK for Android

The Google VR SDK for Android supports both Daydream and Cardboard, including a simple API used for creating apps inserted into Cardboard viewers, and the more complex API for supporting Daydream-ready phones and the Daydream controller.
安卓版Google VR SDK同时支持Daydream和Cardboard设备，它包含一个简单API可以用来创建适配Cardboard的应用，同时它含一个复杂的API用来创建适配Daydream手机设备、控制器的应用。
The Google VR NDK for Android provides a C/C++ API for developers writing native code.
安卓版Google VR NDK提供了C/C++ API，可以让开发者编写本地代码。
Developers familiar with OpenGL can quickly start creating VR applications using the Google VR SDK, simplifying common VR development tasks such as:
熟悉OpenGL的开发者可以很快学会开发VR应用，可以简化了常见的VR开发任务，例如：

• Lens distortion correction.镜头失真校正。
• Spatial audio.空间音频。
• Head tracking.头部跟踪。
• 3D calibration.3D校准。
• Side-by-side rendering.并排渲染。
• Stereo geometry configuration.立体几何配置。
• User input event handling.用户输入事件处理。

We're keeping the hardware and software open to encourage community participation and compatibility with VR content available elsewhere.
我们坚持让硬件和软件开源，鼓励开发者参与社区交流，使VR内容可以随处可见。(我猜的-_-!!)
To learn more:

• Use our Get Started guide for the Android SDK and NDK.
• Download the Google VR SDK for Android.
• To explore the Google VR API, see the Android API Reference.

二、Getting Started for Android SDK

This document describes how to get started using the Google VR for Android SDK by building and running one of our sample apps on your Android device.
这篇文档描述了如何在你的Android设备上构建和运行示例应用，以此让你学会如何使用安卓版Google VR SDK。

01-Treasure Hunt(寻宝) sample app

You will build the Treasure Hunt app, which uses the following features of the Google VR SDK:
你将构建一个“寻宝”应用，它运用了Google VR SDK的如下特点：

• Binocular rendering: A split-screen(分屏) view for each eye in VR.双目渲染
• Spatial audio: Sound seems to come from specific(具体) areas of the VR world.空间音频。
• Head movement tracking: The VR world view updates as the user moves their head.头部运动跟踪
• Trigger input: The user can interact(相互作用) with the VR world by pressing a button.触发输入

In this game, you'll look around the game world to find and collect objects as quickly as possible. It's a basic game, but it demonstrates the core features of the Google VR SDK.
在这个游戏中，你将环顾游戏世界，并且尽快地去找到和收集游戏对象。这是一个相当基础的游戏，但它演示了谷歌VR SDK的核心功能。

02-Open and run Treasure Hunt

Prerequisites(先决条件)

Building the sample app requires:

• Android Studio, 1.0 or higher.
• Version 23 of the Android SDK.(ps:需要注意示例build.gradle文件中buildToolsVersion，与你SDK目录中的build-tools的版本号是否匹配，这是一个坑！！)
• Gradle 23.0.1 or higher. Android Studio will allow you to upgrade if your installed version is too low.
• A physical Android device running Android 4.4 (KitKat) or higher.

Download the sample code

Clone the sample app from the gvr-android-sdk GitHub repository by running the following command:

git clone https://github.com/googlevr/gvr-android-sdk.git

Build the sample app

1.Open Android Studio. On the Welcome to Android Studio screen, choose Open an existing Android Studio project, and select the android-sdk directory. Android Studio will display the various gradle modules on the Project tab on the left side and the various run targets on the top toolbar.
(ps:请注意项目是否构建成功，构建失败的话将无法看到图中的效果。)

2.Connect your phone to your machine, select the samples-treasurehunt target and click Run to compile and run the application on your phone.

For more information about the code behind the Treasure Hunt game, see our explanation of it in the samples section.

03-Start your own project

Using Android Studio

After you've read up on the Google VR SDK for Android, it'll be time to create your own applications. Here's how.
当你阅读完以上的内容后，是时候开始创建你自己的应用了。

1.First, grab all the required .AAR files from the libraries folder of the sdk. To determine which .AARs you need to depend on, you can examine the build.gradle files of the various sample apps. For example, samples/treasurehunt/build.gradle's dependency section has the following entries(条目):
首先从libraries文件夹中抓取所有你需要的.AAR文件，判断哪些.AARs文件是你需要依赖的。作为参考，你可以检查不同实例应用目录下的build.gradle文件。例如，samples/treasurehunt/build.gradle项目文件中依赖了如下的条目：

dependencies {
  compile project(':libraries-audio')
  compile project(':libraries-base')
  compile project(':libraries-common')

  compile 'com.google.protobuf.nano:protobuf-javanano:3.0.0-alpha-7'
}

This indicates that an application similar to the Treasure Hunt sample needs the audio, base, and common libraries.

2.Create new modules for each of these libraries. Using Android Studio's GUI, this can be done via File -> New -> New Module. Select Import .JAR/.AAR Package. Locate one of the .AARs and import it.

3.Then add this new module as a dependency to your main app via File > Project Structure > Modules (on the left side's section list) > YOUR APP's MODULE NAME > Dependencies (on the right side's tab list) -> '+' -> Module Dependency.

Once this is done for all of the required libraries, you will be able to reference code in the Google VR SDK in your app.

Directly using Gradle

Using the steps above will cause Android Studio to generate new modules and edit your .gradle files automatically. Alternatively, you can directly include the .AARs in your application's module by editing that specific module's build.gradle file and adding the following entries:

dependencies {
  compile(name:'audio', ext:'aar')
  compile(name:'common', ext:'aar')
  compile(name:'base', ext:'aar')

  compile 'com.google.protobuf.nano:protobuf-javanano:3.0.0-alpha-7'
}

repositories{
  flatDir{
    dirs 'libs'
  }
}

This will tell Gradle to look in the libs subdirectory of your module for the three .AARs. Create that libs subdirectory inside your module's directory and copy the .AARs there. You will need to repeat this for every module that uses those .AARs which will lead to many duplicate .AARs as your project becomes more complex.

Using ProGuard with Google VR

If you are using ProGuard with your project, make sure it keeps the code used by Google VR. We do this in our code samples build.gradle file with the following:

android {
    ...
    buildTypes {
        release {
            minifyEnabled true
            proguardFiles.add(file('../../proguard-gvr.txt'))
        }
    }
}

where proguard-gvr.txt contains the ProGuard rules you need.