This simple app displays particles moving thanks to some attraction points that you can move by touching them. By default the app displays 50,000 particles and has a maximum of 5 attraction points (you can change these parameters in the Renderer if you want. You'll have to recompile and install your own APK though). The particles color represents their speed: blue for slow particles, red for fast particles.
If you want a simple example on how to use OpenGL ES and RenderScript, then this app may be just what you need (after checking out the Android tutorials). I initially wanted to learn how to use RenderScript and found [this code] (https://code.google.com/p/renderscript-examples/wiki/Gravity). However most of the APIs were deprecated and I ended up rewriting it almost completely, adding some new features on the way (e.g. several attraction points and colors depending on the particle speed).
The following are general guidelines to compile and install an app on your device (assuming this is
a gradle project). Because you don't have the keystore you cannot sign the release version of the
app and you must use app-debug.apk (which is signed with a debug key). You cannot install an APK
which is not signed on your device.
First, you need to have an environment variable JAVA_HOME pointing to your java SDK and another one
ANDROID_HOME pointing to your Android SDK (you can also create a local.properties file containing
sdk.dir=<PATH TO YOUR ANDROID SDK> in the root directory of the project. Then just do:
$ ./gradlew build
This will generate the APK under ./app/build/outputs/apk/.
If for some reasons you don't want to use the gradle wrapper (gradlew), or if the wrapper is
missing, you can download gradle manually (www.gradle.org) and make sure the bin
directory is in your PATH environment variable. Then run $ gradle build (the APKs will also be
generated in ./app/build/outputs/apks/).
You can either create the new project with "Check out project from Version Control" and use the github URL for this project, or if you already downloaded the code you can use "Import project (Eclipse ADT, Gradle, etc.)".
When your project is created, you just need to build it, plug your device and start the app.
If you just want the APK, you'll still need to run the app once, or at least click on the Run icon
until you get the 'Choose Device' dialog (you don't even need to have a real device connected, you
can then click cancel). Just building the project is not enough to create the APKs on Android
Studio. Again, the APKs are located under ./app/build/outputs/apk/.
To install the APK on your device, you can either start the app using Android Studio (it will compile and install the APK automatically), or you can use a terminal, go to the APK directory and do
$ adb install app-debug.apk
(assuming you have only one device connected to your computer).