version: "1.0.0" name: filament-build-clean description: > Clean and build Filament targets for development, debugging, and production. Use this skill whenever you need to clean the workspace or compile desktop targets.

Filament Build & Clean Protocols

This skill defines standard procedures and command configurations for cleaning build artifacts and compiling Filament targets on desktop platforms.

1. Full Clean of All Builds

To completely reset the build environment and remove all compiled artifacts, caches, and generated files across all platforms:

./build.sh -C

2. Compiling Desktop Debug Build

For active development, local debugging, and interactive testing, compile the desktop target with debug symbols and no optimizations:

./build.sh -ip desktop debug

3. Compiling Desktop Release Build

For performance analysis, optimizations, profiling, and running local benchmarks on desktop systems, compile the release build:

./build.sh -ip desktop release

4. Incremental Builds with Ninja

For fast iteration you may invoke ninja directly against an existing build directory:

ninja -C out/cmake-debug <target>

Beware of the second build directory. Materials are not compiled by out/cmake-debug/tools/matc/matc. Every material rule in build.ninja invokes the split-build copy of the host tools at out/prebuilt-tools-release/tools/matc/matc. See build_tools_for_split_build in build.sh; note that SPLIT_BUILD_TYPE defaults to release, so this path is prebuilt-tools-release even for a debug build.

As a result, after changing anything that feeds shader generation — libs/filamat/, libs/filabridge/, shaders/, or third_party/spirv-cross/ — a plain ninja -C out/cmake-debug will rebuild and relink binaries while silently reusing stale `.filamat` files. This produces confusing runtime shader compilation errors in which freshly generated code is mixed with previously generated code.

Rebuild the host tools first:

ninja -C out/prebuilt-tools-release matc resgen
ninja -C out/cmake-debug <target>

./build.sh -ip desktop debug performs both steps automatically, so prefer it when in doubt.