Build Assimp for Android

Assimp is an open source library that allows reading and writing several 3D file formats. In the age of metaverse, If we have to reuse all that investment that we already made in building 3D content — Assimp provides a way. In this article, we are just going to see how to build this library for Android target.

Steps:

1. Pull an Ubuntu base docker image

docker pull ubuntu:bionic

2. Run docker and enter into bash

docker run -v <hostfolder>:/data -it ubuntu:bionic /bin/bash

3. Update Ubuntu repos

apt-get update

4. Install the build tools. This may take few minutes to complete.

apt-get install -y git cmake build-essential software-properties-common wget unzip

5. Install the compilers

add-apt-repository ppa:ubuntu-toolchain-r/test && apt-get update && apt-get install -y gcc g++

6. Install Android NDK

export ANDROID_NDK_HOME="/opt/android-ndk"
export ANDROID_NDK_VERSION="r22"
wget -q https://dl.google.com/android/repository/android-ndk-${ANDROID_NDK_VERSION}-linux-x86_64.zip
unzip android-ndk-${ANDROID_NDK_VERSION}-linux-x86_64.zip
mv android-ndk-${ANDROID_NDK_VERSION} /opt/android-ndk
rm android-ndk-${ANDROID_NDK_VERSION}-linux-x86_64.zip

7. Clone the assimp repository

git clone https://github.com/assimp/assimp.git /opt/assimp
cd /opt/assimp/

8. Checkout assimp git repo and apply a patch

cd /opt/assimp/
git checkout master

Apply the following patch to port/AndroidJNI/CMakeLists.txt

9.Build it. -DANDROID_ABI can be one of armeabi-v7a, arm64-v8a, x86 and x86_64

cd /opt/assimp/
mkdir build && cd build 
cmake -DCMAKE_BUILD_TYPE=Release -DASSIMP_ANDROID_JNIIOSYSTEM=ON -DCMAKE_TOOLCHAIN_FILE=${ANDROID_NDK_HOME}/build/cmake/android.toolchain.cmake -DANDROID_NDK=${ANDROID_NDK_HOME} -DANDROID_ABI=arm64-v8a -DBUILD_SHARED_LIBS=1  ..
make -j4

The built library can be located in /opt/assimp/build/bin/libassimp.so

If you notice the library size > 100 MB, you may run the NDK strip tool to get rid of the debug symbols bundled in the library

aarch64-linux-android-strip -g -S -d --strip-debug --verbose /opt/assimp/build/bin/libassimp.so