The Filament Tools Gradle Plugin helps integrate Filament into your Android project. It automates the use of Filament's command-line tools (matc, cmgen, and filamesh).

This plugin handles:

Material Compilation: Compiles .mat material definitions into .filamat binaries.
IBL Generation: Generates Image-Based Lighting assets from HDR environment maps.
Mesh Compilation: Converts models into Filament's efficient .filamesh binary format. Note: This tool is no longer recommended; instead, use glTF and Filament's gltfio library for model loading.

The plugin hooks directly into the Android build lifecycle (via preBuild) and supports incremental builds, so assets are only recompiled when source files change.

Usage

Apply the plugin in your module's build.gradle file and configure the filament block. You can specify inputs and outputs for any combination of materials, IBLs, or meshes. If a path is not configured, the corresponding task will be disabled.

Example Configuration

plugins {
    id 'filament-plugin'
}

filament {
    materialInputDir = project.layout.projectDirectory.dir("src/main/materials")
    materialOutputDir = project.layout.projectDirectory.dir("src/main/assets/materials")

    iblInputFile = project.layout.projectDirectory.file("path/to/environment.hdr")
    iblOutputDir = project.layout.projectDirectory.dir("src/main/assets/envs")

    meshInputFile = project.layout.projectDirectory.file("path/to/model.obj")
    meshOutputDir = project.layout.projectDirectory.dir("src/main/assets/models")
}

Configuration Details

materialInputDir: The directory containing your source material definitions (.mat files).
materialOutputDir: The directory where the compiled material files (.filamat) will be generated.
iblInputFile: The source high-dynamic-range image file (e.g., .hdr or .exr) used to generate Image Based Lighting assets.
iblOutputDir: The directory where the generated IBL assets (typically .ktx files) will be placed.
meshInputFile: The source mesh file (e.g., .obj) to be compiled.
meshOutputDir: The directory where the compiled mesh file (.filamesh) will be generated.

Automatically adds tasks to your Android build to compile materials, generate an IBL, and compile a mesh. The plugin hooks into preBuild to ensure assets are generated before the application is built.

Configuration Flags

You can control specific compilation options using Gradle properties (e.g., in gradle.properties or via command line -P).

com.google.android.filament.exclude-vulkan When set to true, the Vulkan backend is excluded from the compiled materials. This can be useful to reduce the size of the generated assets if your application does not target Vulkan. Default: false (Vulkan is included)
com.google.android.filament.include-webgpu When set to true, the WebGPU backend is included in the compiled materials. Use this if you intend to use the materials in a context supporting WebGPU. Default: false

Tools Configuration

The Filament Tools plugin requires some binary tools to be available: matc, cmgen, and filamesh.

There are three ways to configure Filament tools:

Point to a local path directly

filament {
    matc {
        path = "/path/to/matc"
    }

    cmgen {
        path = "/path/to/cmgen"
    }

    filamesh {
        path = "/path/to/filamesh"
    }
}

Point to a Maven artifact

filament {
    matc {
        // The minor version (the middle number) must match the Filament dependency's.
        artifact = 'com.google.android.filament:matc:1.68.5'
    }

    cmgen {
        artifact = 'com.google.android.filament:cmgen:1.68.5'
    }
}

Note that the filamesh artifact is not hosted on Maven Central, so it must be provided locally or via another mechanism if needed.

Gradle will automatically handle downloading the tool appropriate for your machine (MacOS/Linux/Windows) from Maven.

Set the com.google.android.filament.tools-dir Gradle property

This will override any other configuration. Gradle will attempt to locate the tools under <tools-dir>/bin (e.g., .../bin/matc, .../bin/cmgen, .../bin/filamesh).