Background

This repository is a porting from the Android NDK example More Teapots to a WebAssembly application. The porting code may be found under the directory of wasm.

The project has two goals. The first one is to evaluate the engineering cost of porting an Android application to WASM. The other one is trying to figure out the performance overhead of WASM, compared to native Androis apps. In addition, I also ported a comparative WebJS version of this teapot program, which is under webGL.

Pre-requisites

Android

1. Download and install Android Studio 2.1 from the link or you may choose just to download the command line tools. Both will work.
2. Download and install the latest version of NDK from the link.
3. Make sure the Android SDK Build-tools version 23.0.3 are installed. (This is referenced by android/nativeactivity/build.gradle .) Use the tools/android command to install it. (As of this writing, version 24 of these tools are installed by default.)
4. Set the ANDROID_HOME and ANDROID_NDK_HOME environment variables. On macOS these are typically:

• export ANDROID_HOME=/Users/[username]/Library/Android/sdk
• export ANDROID_NDK_HOME=/Users/[username]/Library/Android/sdk/ndk-bundle

Wasm

1. Emscripten version 1.36.5
2. Emscripten clang version 1.36.5 (https://github.com/kripken/emscripten-fastcomp-clang 4fddcbc67c8950a54b169030ad9b2d66288d5d5f)
3. Emscripten llvm version 1.36.5 (https://github.com/kripken/emscripten-fastcomp 21f1267bad4d8c523fae483104d4348cfb279cfe)
4. For building emscripten and other required toolchains from source, you may refer to this page

Build

Android

1. cd android into the root directory of Android project.
2. Run ./gradlew assembleDebug
3. The generated apk file should be located at android/app/build/outputs/apk/app-debug.apk
4. To install it on the phone (In our experiment, we use Nexus 5 Build/LMY49P, Android 5.1.1), you first connect the phone to the desktop in debug mode, and then run adb install -r <path-to-your-apk>

Wasm

1. cd wasm
2. Run script ./recompile. The wasm files will be compiled in the wasm/build

RUN

Android

1. To run it on emulator: run android avd first and create an Emulator. After you have created one, use emulator -avd <name> to start it. Then you can run adb install -r <path-to-your-apk> to install apk on your emulator.
2. To run it on the phone, just connect the phone to the desktop in debug mode and then run adb install -r <path-to-your-apk> to install apk on your phone.

WASM

1. To run wams application on Chrome, you need to build the latest chromium from source. In our experiment, we used Version 53.0.2775.0 (64-bit).
2. To run wasm on Chrome on Android, you need also get the Developer version Chrome (You can actually download it from Play Store). In our experiment, we use Chrome Dev 53.0.2782.9.

WebGL

1. The webGL files are under the directory webGL

MACROS

Because what we want to do is a comparative experiment finding the graphical performance bottlenecks in wasm, we defined some macros in order to play around and see what kind of things affect the performance most. All macros should be defined in the 'Define macros' section in common/MoreTeapotsRenderer.cpp.

1. Define TEAPOT if you want to draw one instance as a teapot. Define TRIANGLE if you want to draw one instance as a simple triangle. Define Zero if you want to draw one instance as purely a bunch of points located at 0. You must and can only define one macro from one of these three macros.
2. To control the number of instances and the size of one instance,
   • Variables NUM_TEAPOT_X, NUM_TEAPOT_Y and NUM_TEAPOT_Z defined in app/src/main/jni/MoreTeapotsNativeActivity.cpp controls the number of instances drawn along X-axis, Y-axis, Z-axis in Android application. Variables NUM_TEAPOTS_X, NUM_TEAPOTS_Y and NUM_TEAPOTS_Z defined in wasm/MoreTeapots-wasm.cpp controls the number of instances in wasm application.
   • Variable size_instance_ defined in common/MoreTeapotsRenderer.cpp defined the size (number of vertices, also the number of indices) of per instance. That is to say, if you set it to 1, then it remains the same size for one instance. It you set to 2, the size of per instance will become two times than the original one. If you also set the variable offset in Init() larger than 0, then each 'copy' of the original instance will have an offset in the new 'larger' instance.
3. (Optional) Define DRAW_ALL_IN_MIDDLE if you want to draw all instances in the middle of the screen. Otherwise, each instance will have a distance from other instances.
4. (Optional) Define SIMPLE_SHADER if you want use a really simple shader to output solid color.
5. (Optional) Define MULTI_GL_SET_UNIFORM if you want to call glUniform4f in a loop in order to find whether indirect calls to GL APIs is a heavy bottleneck for the performance.

Below is the README from the original project.

More Teapots

More Teapots is an Android C++ sample that draws multiple instances of the same Teapot mesh using GLES 3.0 Instanced Rendering and NativeActivity.

This sample uses the new Gradle Experimental Android plugin with C++ support.

Pre-requisites

• Android Studio 1.3+ with NDK bundle.

Getting Started

1. Download Android Studio
2. Launch Android Studio.
3. Open the sample directory.
4. Open File/Project Structure...

• Click Download or Select NDK location.

1. Click Tools/Android/Sync Project with Gradle Files.
2. Click Run/Run 'app'.

Screenshots

Support

If you've found an error in these samples, please file an issue.

Patches are encouraged, and may be submitted by forking this project and submitting a pull request through GitHub. Please see CONTRIBUTING.md for more details.

• Stack Overflow
• Google+ Community
• Android Tools Feedbacks

License

Copyright 2015 Google, Inc.

Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.