Mist

Prototype for connecting Android-based VR headsets (currently targeting and testing on the original Oculus Quest) to the GrapeVine, which I'm calling "Mist" at the moment.

The VDRIVER code is being developed in the AQUA monorepo. This repo just contains the code for the Android app, which interacts with the headset through OpenXR and which uses OpenGL ES to render the virtual environment and desktop.

Firefox in "serenity" environment	htop in "galaxy" environment	Firefox in "galaxy" environment

Building

Gradle makes me sad and I kind of despise Android Studio, so I'm doing this manually in a build.sh script. Eventually I wanna integrate this with the Bob buildsystem, but for now, especially as I'm still shaky about how all this Android stuff works, its easier to prototype like this.

This expects you to have an Android SDK and NDK already installed, which you can either download with Android Studio or (preferably) with sdkmanager. You also have to point build.sh to the SDK through the ANDROID_SDK variable (in config.sh). When I add Android support to Bob the Builder, I will make it integrate with sdkmanager.

To build the APK, simply run:

sh build.sh

This command will generate a signed APK in .out/Mist.apk.

Installing & debugging

Installing:

adb install .out/Mist.apk

Debugging (i.e. starting and logging):

adb shell am start -n com.inobulles.mist/android.app.NativeActivity
adb logcat | grep native-activity

Executing AQUA binaries

As of Android SDK 29, Android does not allow you to execute arbitrary binaries anymore, which obviously is a problem for the AQUA binaries - notably the GrapeVine daemon - which must run on Mist. This is a problem Termux faces too of course: https://github.com/termux/termux-packages/wiki/Termux-execution-environment.

There are a couple potential solutions to this:

• Stick to Android SDK 28. What I and Termux are doing at the moment but I don't want this to be a long-term solution.
• Option to build gvd as a shared library and run it in the same process as Mist. This is possible but sounds like a lot of work, and means that a crashing VDEV means all of Mist crashes (right?).
• Something else. Termux is a good space to keep an eye on.

Resources

• Slightly out of date, but helped me with the steps to build APKs outside of Android Studio: https://github.com/skanti/Android-Manual-Build-Command-Line
• Way nicer and clearer OpenXR examples than hello_xr: https://github.com/KhronosGroup/OpenXR-Tutorials
• Space HDRi that I'm using for the space environment: https://blenderartists.org/t/free-space-hdri/1517850