Building filament 1.67 for Android on mac - AI powered

[pannonianknight]

Hi,

recently i had started to thinker and experiment with filament. Need a lightweight multiplatform render engine.

Im more a designer then developer, heck, honestly, im not even a D in that word developer. But i found some courage in Cursor and other llms.

I managed to get filament working on iOS, was a fight but it works.
Then came andorid, boy was it hair pulling.

But i managed. Tought i share my findings with the world. Maybe could save some one some hair.

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Filament Build Instructions for Android

Documentation for building Filament rendering engine for Android with c++_shared standard library and C++17 standard.

📋 Prerequisites

Android SDK & NDK

• Android SDK: Installed via Android Studio
• NDK Version: 25.1.8937393
• NDK Path: /Users/marko/Library/Android/sdk/ndk/25.1.8937393
• CMake Version: 3.22.1 (comes with Android SDK)

Java

• Java Version: Java 17+ (Android Studio bundled JDK)
• JAVA_HOME: Set automatically by Android Studio

Build Tools

• Gradle: 8.0+ (comes with Android Studio)
• Ninja: Comes with CMake

🔧 Filament Build Configuration

1. C++ Standard Library: c++_shared

Problem: gltfio::ResourceLoader uses std::stringstream which has known linking issues with c++_static on Android NDK.

Solution: Build Filament with c++_shared instead of c++_static.

2. C++ Standard: C++17 with C++20 Extensions

Problem: Filament source uses some C++20 features (e.g., explicit capture of 'this' with a capture default of '=').

Solution: Build with C++17 standard but allow C++20 extensions.

📝 Build Steps

Step 1: Create filament-cpp17.cmake

Create the file in Filament root directory:

# filament-cpp17.cmake
# Enforce C++17 but allow C++20 extensions for Filament source

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)
add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-std=c++17>)
add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-Wno-c++20-extensions>)

Location: /Users/marko/Desktop/OpenSource/filament/filament-cpp17.cmake

Step 2: Include filament-cpp17.cmake in Filament CMakeLists.txt

Add at the beginning of the main CMakeLists.txt:

# CMakeLists.txt (root Filament directory)
if (ANDROID)
    include(${CMAKE_CURRENT_SOURCE_DIR}/filament-cpp17.cmake)
endif()

Location: /Users/marko/Desktop/OpenSource/filament/CMakeLists.txt

Step 3: Update Android build.gradle

Change -DANDROID_STL=c++_static to -DANDROID_STL=c++_shared:

// android/build.gradle
ext.cmakeArgs = [
    // ... other args ...
    "-DANDROID_STL=c++_shared",  // ← CHANGED: c++_static → c++_shared
    // ... other args ...
]

Location: /Users/marko/Desktop/OpenSource/filament/android/build.gradle

Step 4: Build Filament

export ANDROID_HOME="/Users/marko/Library/Android/sdk"
export PATH="/Users/marko/Library/Android/sdk/cmake/3.22.1/bin:$PATH"

cd /Users/marko/Desktop/OpenSource/filament

# Clean build (optional)
./build.sh -c -p android release

# Build for arm64-v8a (production)
./build.sh -p android -q arm64-v8a release

Build Output:

• Location: /Users/marko/Desktop/OpenSource/filament/out/android-release/filament
• Libraries: lib/${ANDROID_ABI}/lib*.a
• Headers: include/

Step 5: Verify Build Output

ls -lh /Users/marko/Desktop/OpenSource/filament/out/android-release/filament/lib/arm64-v8a/

You should see:

• libfilament.a
• libgltfio_core.a
• libktxreader.a
• libbasis_transcoder.a
• ... and other libraries

🔗 Android App Integration

1. CMakeLists.txt Configuration

# app/src/main/cpp/CMakeLists.txt

# Filament paths
set(FILAMENT_DIR "/Users/marko/Desktop/OpenSource/filament/out/android-release/filament")
set(FILAMENT_INCLUDE_DIR "${FILAMENT_DIR}/include")
set(FILAMENT_LIB_DIR "${FILAMENT_DIR}/lib/${ANDROID_ABI}")

# Link c++_shared
target_link_libraries(core3d-native
    # ... other libs ...
    c++_shared  # ← CHANGED from c++_static
)

# Compiler flags
target_compile_options(core3d-native PRIVATE
    -Wall
    -Wextra
    -Wno-c++20-extensions  # Allow Filament C++20 features
)

2. Gradle Configuration

// app/build.gradle.kts

defaultConfig {
    externalNativeBuild {
        cmake {
            cppFlags += listOf("-std=c++17", "-Wno-c++20-extensions")
            arguments += listOf(
                "-DANDROID_STL=c++_shared",  // ← CHANGED
                "-DANDROID_PLATFORM=android-26"
            )
            abiFilters += listOf("arm64-v8a")
        }
    }
}

3. Include libc++_shared.so in APK

Option A: Manual Copy (Recommended)

mkdir -p app/src/main/jniLibs/arm64-v8a
cp ${ANDROID_NDK}/toolchains/llvm/prebuilt/darwin-x86_64/sysroot/usr/lib/aarch64-linux-android/libc++_shared.so \
   app/src/main/jniLibs/arm64-v8a/

Option B: Gradle sourceSets (Alternative)

sourceSets {
    getByName("main") {
        jniLibs.srcDirs(
            "src/main/jniLibs",
            "${android.ndkDirectory}/toolchains/llvm/prebuilt/darwin-x86_64/sysroot/usr/lib/aarch64-linux-android"
        )
    }
}

✅ Build Verification

1. Verify if the app builds

cd /Users/marko/Desktop/GIT/3d-companion-app-filament-Android
./gradlew :app:assembleDebug

2. Verify that libc++_shared.so exists in APK

unzip -l app/build/outputs/apk/debug/app-debug.apk | grep libc++_shared.so

3. Runtime Verification

In logcat you should see:

✅ Filament JNI initialized
✅ Engine
✅ ResourceLoader created (c++_shared)
✅ Resources loaded (textures + materials) [c++_shared]

🐛 Resolved Issues

Issue 1: stringstream Linker Error

Error: ld: error: undefined symbol: vtable for std::__ndk1::basic_stringstream

Solution: Switch from c++_static to c++_shared in Filament build and app configuration.

Issue 2: C++20 Extensions Error

Error: explicit capture of 'this' with a capture default of '=' is a C++20 extension

Solution: Add -Wno-c++20-extensions flag to compiler options.

Issue 3: libc++_shared.so Not Found

Error: java.lang.UnsatisfiedLinkError: dlopen failed: library "libc++_shared.so" not found

Solution: Copy libc++_shared.so from NDK to app/src/main/jniLibs/arm64-v8a/.

📦 Build Artifacts

Filament Libraries (arm64-v8a)

out/android-release/filament/lib/arm64-v8a/
├── libfilament.a
├── libbackend.a
├── libgltfio_core.a
├── libktxreader.a
├── libbasis_transcoder.a
├── libuberarchive.a
├── libimage.a
├── libibl.a
└── ... (other libraries)

Filament Headers

out/android-release/filament/include/
├── filament/
├── gltfio/
├── ktxreader/
├── image/
└── ... (other headers)

🔄 Rebuild Filament

If you need to rebuild Filament after changes:

cd /Users/marko/Desktop/OpenSource/filament

# Clean build
./build.sh -c -p android -q arm64-v8a release

# Or just rebuild
./build.sh -p android -q arm64-v8a release

📚 Reference

• Filament GitHub: https://github.com/google/filament
• Android NDK Docs: https://developer.android.com/ndk
• CMake Documentation: https://cmake.org/documentation/

✨ Final Notes

• C++ Standard: C++17 with allowed C++20 extensions
• Standard Library: c++_shared (required for ResourceLoader)
• Build Type: Release (optimized)
• ABI: arm64-v8a (64-bit ARM)
• Platform: android-26 (Android 8.0+)

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Date: 2025-11-12
Filament Version: Latest (from OpenSource/filament)
Android NDK: 25.1.8937393
CMake: 3.22.1