### Quick Example: Import and List Geometry Module

Source: https://github.com/facebookresearch/momentum/blob/main/README.md

Installs pymomentum via conda and then imports and lists the contents of the geometry module.

```bash
# Install and run
conda install -c conda-forge pymomentum
python -c "import pymomentum.geometry as geom; print(dir(geom))"
```

--------------------------------

### Warning for Install Examples Without Building

Source: https://github.com/facebookresearch/momentum/blob/main/CMakeLists.txt

Checks if MOMENTUM_INSTALL_EXAMPLES is ON while MOMENTUM_BUILD_EXAMPLES is OFF. If so, it issues a warning indicating that no examples will be built or installed.

```cmake
if(MOMENTUM_INSTALL_EXAMPLES AND NOT MOMENTUM_BUILD_EXAMPLES)
  message(WARNING "MOMENTUM_INSTALL_EXAMPLES is ON, but MOMENTUM_BUILD_EXAMPLES is OFF. No examples will be built or installed.")
endif()
```

--------------------------------

### Run Other Examples

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/01_getting_started.md

View help for running other examples, such as the glb_viewer. Refer to the Examples page for a full list.

```bash
pixi run glb_viewer --help
```

--------------------------------

### Run Hello World Example

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/01_getting_started.md

Execute the 'hello_world' example using Pixi. Alternatively, you can run the executable directly from the build directory.

```bash
pixi run hello_world
```

```bash
# Linux and macOS
./build/hello_world

# Windows
./build/Release/hello_world.exe
```

--------------------------------

### Start Local Development Server

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/README.md

Starts a local development server. Changes are reflected live without a server restart.

```bash
$ yarn start
```

--------------------------------

### Clone and Setup Repository

Source: https://github.com/facebookresearch/momentum/blob/main/CONTRIBUTING.md

Clone the repository and set up the upstream remote for fetching changes.

```bash
git clone https://github.com/YOUR_USERNAME/momentum.git
cd momentum
git remote add upstream https://github.com/facebookresearch/momentum.git
```

--------------------------------

### Setting up Environment with Pixi

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_python/03_developer_guide/04_conda_publishing.md

Command to install project dependencies using the pixi package manager.

```bash
pixi install
```

--------------------------------

### Install Rerun SDK

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/01_viewers.md

Install the Rerun SDK using pixi. Ensure the version matches the one used by Momentum.

```bash
pixi global install rerun-sdk==<same_rerun_sdk_version>
```

--------------------------------

### Install PyMomentum with uv or pip

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_python/01_user_guide/01_getting_started.md

Install PyMomentum from PyPI using uv (recommended) or pip. Explicitly choose CPU or GPU versions.

```bash
# Using uv (preferred over pip)
uv add pymomentum-cpu   # CPU version
uv add pymomentum-gpu   # GPU version (requires CUDA)

# Alternative: Using pip
pip install pymomentum-cpu
pip install pymomentum-gpu
```

--------------------------------

### Install Momentum with Conda/Pixi

Source: https://github.com/facebookresearch/momentum/blob/main/README.md

Recommended installation methods using Conda or Pixi for Python and C++.

```bash
pixi add pymomentum             # Auto-detects GPU/CPU
conda install -c conda-forge pymomentum
```

```bash
# C++ (Conda/Pixi)
pixi add momentum-cpp
conda install -c conda-forge momentum-cpp
```

--------------------------------

### Install Momentum Headers

Source: https://github.com/facebookresearch/momentum/blob/main/CMakeLists.txt

Installs the header files for the Momentum library. It excludes example, test, and website-related directories to keep the installation clean.

```cmake
install(
  DIRECTORY momentum
  DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
  COMPONENT headers
  FILES_MATCHING PATTERN "*.h"
  PATTERN "*/examples/*" EXCLUDE
  PATTERN "*/test/*" EXCLUDE
  PATTERN "*/website/*" EXCLUDE
)
```

--------------------------------

### Install Momentum with PyPI (Experimental)

Source: https://github.com/facebookresearch/momentum/blob/main/README.md

Experimental installation using pip for CPU or GPU versions. Use Conda or Pixi for a more stable experience.

```bash
pip install pymomentum-cpu      # CPU version
```

```bash
pip install pymomentum-gpu      # GPU version with CUDA
```

--------------------------------

### Install Dependencies with Yarn

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/README.md

Run this command to install project dependencies using Yarn.

```bash
$ yarn
```

--------------------------------

### Install Momentum Targets (Libraries)

Source: https://github.com/facebookresearch/momentum/blob/main/CMakeLists.txt

Installs the Momentum libraries, exporting them with the 'momentumTargets' target and setting up runtime, archive, and library destinations. It also installs the export set.

```cmake
install(
  TARGETS ${targets}
  EXPORT momentumTargets
  RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
  ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}"
  LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}"
)
install(
  EXPORT momentumTargets
  NAMESPACE momentum::
  DESTINATION ${MOMENTUM_CONFIG_INSTALL_DIR}
)
```

--------------------------------

### Tests, Tutorials, and Examples Header Inclusion

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/04_developer_guide/02_style_guide.md

Use angle brackets for header inclusion in tests, tutorials, and example code. This mirrors the external user experience and demonstrates correct header usage for installed libraries.

```cpp
// In test files, tutorials, and examples
#include <momentum/character/character.h>
#include <momentum/common/checks.h>
```

--------------------------------

### Build Momentum from Source

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/01_getting_started.md

Build the Momentum C++ project. The first run may take a few minutes to install dependencies.

```bash
pixi run build
```

--------------------------------

### Install Momentum Executables

Source: https://github.com/facebookresearch/momentum/blob/main/CMakeLists.txt

Installs the built Momentum executables to the runtime destination directory.

```cmake
install(
  TARGETS ${executables}
  RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
)
```

--------------------------------

### Build Momentum from Source

Source: https://github.com/facebookresearch/momentum/blob/main/README.md

Clones the repository, navigates into the directory, and uses Pixi to build the C++ library and Python bindings, run tests, or execute an example.

```bash
git clone https://github.com/facebookresearch/momentum
cd momentum
pixi run build      # Builds C++ library and Python bindings
pixi run test       # Runs tests
pixi run hello_world  # Runs example
```

--------------------------------

### Install Momentum Libraries and Executables

Source: https://github.com/facebookresearch/momentum/blob/main/CMakeLists.txt

Installs the Momentum libraries and executables based on the 'targets' and 'executables' properties. It also provides status messages for the installation process.

```cmake
get_property(targets GLOBAL PROPERTY MOMENTUM_TARGETS)
get_property(executables GLOBAL PROPERTY MOMENTUM_EXECUTABLES)

if(targets)
  message(STATUS "[Installing libraries]")
  foreach(target ${targets})
    message(STATUS "  - ${target}")
  endforeach()
else()
  message(STATUS "No libraries to install.")
endif()

if(executables)
  message(STATUS "[Installing executables]")
  foreach(executable ${executables})
    message(STATUS "  - ${executable}")
  endforeach()
else()
  message(STATUS "No executables to install.")
endif()
```

--------------------------------

### Enable Testing and Setup Google Test

Source: https://github.com/facebookresearch/momentum/blob/main/CMakeLists.txt

Enables the testing framework and sets up Google Test. This should be done before defining any tests.

```cmake
if(MOMENTUM_BUILD_TESTING)
  find_package(Boost CONFIG REQUIRED)

  enable_testing()
  mt_setup_gtest()

  mt_library(
    NAME test_helpers
    HEADERS_VARS test_helpers_public_headers
    SOURCES_VARS test_helpers_sources
    PUBLIC_LINK_LIBRARIES
      common
      GTest::gtest
    PRIVATE_LINK_LIBRARIES
      Boost::boost
    NO_INSTALL
  )

  mt_library(
    NAME character_test_helpers_gtest
    HEADERS_VARS character_test_helpers_gtest_public_headers
    SOURCES_VARS character_test_helpers_gtest_sources
    PUBLIC_LINK_LIBRARIES
      character
    PRIVATE_LINK_LIBRARIES
      GTest::gmock
      GTest::gtest
    NO_INSTALL
  )

  mt_library(
    NAME solver_test_helper
    HEADERS_VARS solver_test_helper_public_headers
    PUBLIC_LINK_LIBRARIES
      solver
    NO_INSTALL
  )

  mt_library(
    NAME error_function_helper
    HEADERS_VARS error_function_helper_public_headers
    SOURCES_VARS error_function_helper_sources
    PUBLIC_LINK_LIBRARIES
      character
      character_solver
    PRIVATE_LINK_LIBRARIES
      GTest::gmock
      GTest::gtest
    NO_INSTALL
  )

  set(io_test_helper_libs )
  if(APPLE)
    set(io_test_helper_sources io_test_helper_sources_macos)
    list(APPEND io_test_helper_libs "-framework Foundation")
  elseif(UNIX)
    set(io_test_helper_sources io_test_helper_sources_linux)
  elseif(WIN32)
    set(io_test_helper_sources io_test_helper_sources_windows)
  else()
    message(FATAL_ERROR "Unsupported platform")
  endif()

  mt_library(
    NAME io_test_helper
    HEADERS_VARS io_test_helper_public_headers
    SOURCES_VARS ${io_test_helper_sources}
    PUBLIC_LINK_LIBRARIES
      test_helpers
      Microsoft.GSL::GSL
    PRIVATE_LINK_LIBRARIES
      ${io_test_helper_libs}
    NO_INSTALL
  )

  mt_test(
    NAME common_test
    SOURCES_VARS common_test_sources
    LINK_LIBRARIES common
  )

  mt_test(
    NAME progress_bar_test
    SOURCES_VARS progress_bar_test_sources
    LINK_LIBRARIES progress_bar
  )

  mt_test(
    NAME simd_test
    SOURCES_VARS simd_test_sources
    LINK_LIBRARIES simd
  )

  mt_test(
    NAME online_qr_test
    SOURCES_VARS online_qr_test_sources
    LINK_LIBRARIES online_qr
  )

  mt_test(
    NAME math_test
    SOURCES_VARS math_test_sources
    LINK_LIBRARIES math
  )

  mt_test(
    NAME coordinate_system_test
    SOURCES_VARS coordinate_system_test_sources
    LINK_LIBRARIES coordinate_system
  )

  mt_test(
    NAME simd_generalized_loss_test
    SOURCES_VARS simd_generalized_loss_test_sources
    LINK_LIBRARIES simd_generalized_loss
  )

  # TODO: Add solver_test

  mt_test(
    NAME character_test
    SOURCES_VARS character_test_sources
    LINK_LIBRARIES
      character
      character_test_helpers
      test_helpers
  )

  mt_test(
    NAME character_solver_test
    SOURCES_VARS character_solver_test_sources
    LINK_LIBRARIES
      character_solver
      character_test_helpers
      error_function_helper
      solver_test_helper
  )

  if(NOT APPLE) # TODO: Fix
    mt_test(
      NAME character_solver_simd_test
      SOURCES_VARS character_solver_simd_test_sources
      LINK_LIBRARIES
        character_solver
        character_solver_simd
        character_test_helpers
        error_function_helper
    )
  endif()

  mt_test(
    NAME character_sequence_solver_test
    SOURCES_VARS character_sequence_solver_test_sources
    LINK_LIBRARIES
      character_sequence_solver
      character_test_helpers
      solver_test_helper
  )

  # TODO: Fix test failures on macOS
  if(NOT APPLE)
    mt_test(
      NAME diff_ik_test
      HEADERS_VARS diff_ik_test_headers
      SOURCES_VARS diff_ik_test_sources
      LINK_LIBRARIES
        character_test_helpers
        diff_ik
        io_gltf
        io_skeleton
    )
  endif()

  mt_test(
    NAME io_common_test
    LINK_LIBRARIES io_common
    SOURCES_VARS io_common_test_sources
  )

  # TODO: Add io_gltf_test

  mt_test(
    NAME io_marker_test
    SOURCES_VARS io_marker_test_sources
    LINK_LIBRARIES
      io_marker
      io_test_helper
    ENV
      "TEST_RESOURCES_PATH=${CMAKE_SOURCE_DIR}/momentum/test/resources"
  )

  mt_test(
    NAME io_shape_test
    SOURCES_VARS io_shape_test_sources
    LINK_LIBRARIES
      character
      character_test_helpers
      io_shape
      io_test_helper
  )

  mt_test(
    NAME io_skeleton_test
    SOURCES_VARS io_skeleton_test_sources
    LINK_LIBRARIES
      character_test_helpers
      io_skeleton
      io_test_helper
      character_test_helpers_gtest
  )

  mt_test(
    NAME io_bvh_test
    SOURCES_VARS io_bvh_test_sources
    LINK_LIBRARIES
      io_bvh
      io_test_helper
    ENV
      "TEST_RESOURCES_PATH=${CMAKE_SOURCE_DIR}/momentum/test/resources"
  )

  mt_test(
    NAME io_motion_test
    SOURCES_VARS io_motion_test_sources
    LINK_LIBRARIES
      character
      character_test_helpers
      io_motion
      io_test_helper
  )

  mt_test(
    NAME io_legacy_json_test

```

--------------------------------

### Install Specific PyMomentum Version with CUDA

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_python/01_user_guide/01_getting_started.md

Install a specific version of PyMomentum, including constraints for CUDA compatibility. This example installs version 0.1.74 with CUDA 12.9 support.

```bash
# Example: Install version 0.1.74 with CUDA 12.9
conda install -c conda-forge pymomentum=0.1.74="cuda129*"
```

--------------------------------

### Install PyMomentum with Pixi

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_python/01_user_guide/01_getting_started.md

Use Pixi to add PyMomentum to your environment. It auto-detects GPU/CPU or allows explicit selection.

```bash
pixi add pymomentum

pixi add pymomentum-cpu  # CPU-only
pixi add pymomentum-gpu  # GPU (CUDA) support
```

--------------------------------

### Convert Model with FBX SDK on Windows (Powershell)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/01_getting_started.md

Example of converting a model to FBX format using Momentum on Windows with FBX SDK support enabled. This command requires the FBX SDK to be installed.

```powershell
$env:MOMENTUM_BUILD_WITH_FBXSDK = "ON"; pixi run convert_model -d <input.glb> -o <out.fbx>
```

--------------------------------

### Build and Install PyMomentum

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_python/01_user_guide/01_getting_started.md

Build and install PyMomentum using pip within your activated conda environment. This method respects the dependencies already installed in your environment.

```bash
pip install .
```

--------------------------------

### Install PyMomentum Package

Source: https://github.com/facebookresearch/momentum/blob/main/pymomentum/CMakeLists.txt

Installs the PyMomentum package using the 'mt_install_pymomentum()' command. This is typically the final step in the build process for deployment.

```cmake
mt_install_pymomentum()
```

--------------------------------

### Build Momentum with FBX SDK on Windows (cmd)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/01_getting_started.md

Build Momentum from source with FBX SDK support enabled on Windows using cmd. The SDK is automatically installed on Linux.

```cmd
set MOMENTUM_BUILD_WITH_FBXSDK=ON && pixi run <target>
```

--------------------------------

### Build export_objs with buck

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/examples/export_objs/README.md

Build the export_objs utility using buck2. This command compiles the necessary components for the example.

```bash
buck2 build path/to/momentum/examples:export_objs
```

--------------------------------

### Install Momentum with Pixi

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/01_getting_started.md

Use Pixi to add the Momentum C++ package to your environment.

```bash
pixi add momentum-cpp
```

--------------------------------

### Installing Specific Conda Package Versions

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_python/03_developer_guide/04_conda_publishing.md

Instructions for installing exact versions of a conda package, including version and build constraints.

```bash
conda install -c conda-forge pymomentum=0.1.77
```

```bash
conda install -c conda-forge "pymomentum=0.1.77=cuda129*"
```

```bash
conda install -c conda-forge "pymomentum=0.1.77=*py312*"
```

--------------------------------

### Define 'hello_world' Executable

Source: https://github.com/facebookresearch/momentum/blob/main/CMakeLists.txt

Defines the 'hello_world' executable, specifying its source files and linked libraries. This is a basic example executable.

```cmake
if(MOMENTUM_BUILD_EXAMPLES)
  mt_executable(
    NAME hello_world
    SOURCES_VARS hello_world_sources
    LINK_LIBRARIES
      math
  )

  mt_executable(
    NAME convert_model
    SOURCES_VARS convert_model_sources
    LINK_LIBRARIES
      io_character
      io_marker
      CLI11::CLI11
  )

  if(MOMENTUM_BUILD_RERUN)
    mt_executable(
      NAME glb_viewer
      SOURCES_VARS glb_viewer_sources
      LINK_LIBRARIES
        io_gltf
        rerun
        CLI11::CLI11
        rerun_sdk
    )

    mt_executable(
      NAME fbx_viewer
      SOURCES_VARS fbx_viewer_sources
      LINK_LIBRARIES
        io_fbx
        rerun
        CLI11::CLI11
        rerun_sdk
    )

    mt_executable(
      NAME c3d_viewer
      SOURCES_VARS c3d_viewer_sources
      LINK_LIBRARIES
        io_marker
        rerun
        CLI11::CLI11
        rerun_sdk
    )

    mt_executable(
      NAME urdf_viewer
      SOURCES_VARS urdf_viewer_sources
      LINK_LIBRARIES
        io_urdf
        rerun
        CLI11::CLI11
        rerun_sdk
    )

    mt_executable(
      NAME bvh_viewer
      SOURCES_VARS bvh_viewer_sources
      LINK_LIBRARIES
        io_bvh
        rerun
        CLI11::CLI11
        rerun_sdk
    )
  endif()

  mt_executable(
    NAME animate_shapes
    SOURCES_VARS animate_shapes_sources
    LINK_LIBRARIES
      io_character
      io_shape
      CLI11::CLI11
  )

  mt_executable(
    NAME process_markers_app
    SOURCES_VARS process_markers_app_sources
    LINK_LIBRARIES
      app_utils
      common
      process_markers
  )

  mt_executable(
    NAME refine_motion
    SOURCES_VARS refine_motion_sources
    LINK_LIBRARIES
      app_utils
      io_gltf
      io_marker
      io_skeleton
      marker_tracker
  )

  mt_executable(
    NAME export_objs
    SOURCES_VARS export_objs_sources
    LINK_LIBRARIES
      character
      io_fbx
      io_gltf
      CLI11::CLI11
  )

  if(MOMENTUM_BUILD_IO_USD AND MOMENTUM_BUILD_RERUN)
    mt_executable(
      NAME usd_viewer
      SOURCES_VARS usd_viewer_sources
      LINK_LIBRARIES
        io_usd
        rerun
        CLI11::CLI11
        rerun_sdk
    )
  endif()

endif()
```

--------------------------------

### Install Momentum with Conda

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/01_getting_started.md

Use Conda to install the Momentum C++ package from the conda-forge channel.

```bash
conda install -c conda-forge momentum-cpp
```

--------------------------------

### Check PyTorch Installation

Source: https://github.com/facebookresearch/momentum/blob/main/pymomentum/CMakeLists.txt

Verifies if PyTorch is installed at the determined base path. If not found, it raises a fatal error.

```cmake
if(NOT EXISTS "${libtorch_base_path}")
  message(FATAL_ERROR
    "PyTorch not found in the expected location: ${libtorch_base_path}.\n"
    "Please ensure PyTorch is installed in your Conda/Pixi environment."
  )
endif()
```

--------------------------------

### Install Momentum

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/02_creating_your_applications.md

Installs Momentum and its dependencies within a Pixi virtual environment. This command builds Momentum in Release mode and sets up environment variables for CMake.

```bash
pixi run install
```

--------------------------------

### Install PyMomentum with Conda

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_python/01_user_guide/01_getting_started.md

Use Conda to install PyMomentum from the conda-forge channel. It supports auto-detection or explicit CPU/GPU backend selection.

```bash
conda install -c conda-forge pymomentum

conda install -c conda-forge pymomentum-cpu  # CPU-only
conda install -c conda-forge pymomentum-gpu  # GPU (CUDA) support
```

--------------------------------

### Build Momentum with FBX SDK on Windows (Powershell)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/01_getting_started.md

Build Momentum from source with FBX SDK support enabled on Windows using Powershell. The SDK is automatically installed on Linux.

```powershell
$env:MOMENTUM_BUILD_WITH_FBXSDK = "ON"; pixi run <target>
```

--------------------------------

### Install Core Dependencies with Conda

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_python/01_user_guide/01_getting_started.md

Install essential dependencies such as PyTorch, Eigen, and Ceres Solver using conda. Adjust versions as needed.

```bash
# Install core dependencies (adjust versions as needed)
conda install -c conda-forge pytorch eigen ceres-solver
```

--------------------------------

### Ground Plane Shadow Generation Setup

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_python/02_examples/02_visualization_pymomentum_rasterizer.md

Sets up lights and a separate z-buffer for generating ground plane shadows using a two-step rasterization process. This technique projects the mesh onto the ground plane to create shadow effects.

```python
# Two lights, the first is above the person and casts shadows while the other
# is co-located with the camera to ensure good fill.
lights = [
    pym_renderer.Light.create_point_light(
        np.asarray([-20, 200, 30]), color=np.asarray([0.7, 0.7, 0.7])
    ),
    pym_renderer.Light.create_point_light(
        camera.center_of_projection,
        np.asarray([0.3, 0.3, 0.3]),
    ),
]

# Create a separate z buffer for the shadows.
shadow_buffer = pym_renderer.create_z_buffer(camera)
# Rasterize the body mesh onto the shadow Z buffer using a projection matrix

```

--------------------------------

### Enable Testing and Setup Google Test

Source: https://github.com/facebookresearch/momentum/blob/main/pymomentum/CMakeLists.txt

Enables testing for the project and sets up Google Test if the MOMENTUM_BUILD_TESTING flag is enabled. This is a prerequisite for running any tests.

```cmake
if(MOMENTUM_BUILD_TESTING)
  enable_testing()
  mt_setup_gtest()
endif()
```

--------------------------------

### Build Momentum with FBX SDK on macOS

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/01_getting_started.md

Build Momentum from source with FBX SDK support enabled on macOS. The SDK is automatically installed on Linux.

```bash
MOMENTUM_BUILD_WITH_FBXSDK=ON pixi run <target>
```

--------------------------------

### Configure and Install CMake Package Config File

Source: https://github.com/facebookresearch/momentum/blob/main/CMakeLists.txt

Generates and installs the 'momentum-config.cmake' file, which is essential for CMake to find and use the Momentum package. It uses CMake's package configuration helpers.

```cmake
include(CMakePackageConfigHelpers)
set(MOMENTUM_CONFIG_INPUT cmake/momentum-config.cmake.in)
set(MOMENTUM_CONFIG_OUTPUT ${CMAKE_BINARY_DIR}/cmake/momentum-config.cmake)
set(MOMENTUM_CONFIG_INSTALL_DIR ${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME})
configure_package_config_file(
  ${MOMENTUM_CONFIG_INPUT}
  ${MOMENTUM_CONFIG_OUTPUT}
  INSTALL_DESTINATION ${MOMENTUM_CONFIG_INSTALL_DIR}
)
install(
  FILES ${MOMENTUM_CONFIG_OUTPUT}
  DESTINATION ${MOMENTUM_CONFIG_INSTALL_DIR}
)
```

--------------------------------

### Fetch pybind11 using FetchContent

Source: https://github.com/facebookresearch/momentum/blob/main/pymomentum/CMakeLists.txt

Includes pybind11 as a dependency using FetchContent if not using a system-wide installation. It specifies the Git repository and tag.

```cmake
include(FetchContent)
FetchContent_Declare(
  pybind11
  GIT_REPOSITORY https://github.com/pybind/pybind11.git
  GIT_TAG v2.13.6
)
set(PYBIND11_TEST OFF CACHE BOOL "" FORCE)
FetchContent_MakeAvailable(pybind11)
```

--------------------------------

### Displaying Conda Package Information

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_python/03_developer_guide/04_conda_publishing.md

Commands to inspect details and installed files of a specific conda package.

```bash
conda info pymomentum
```

```bash
conda list pymomentum --show-channel-urls
```

--------------------------------

### Local Conda Package Building

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_python/03_developer_guide/04_conda_publishing.md

Steps to build a conda package locally using conda-build. Ensure conda-build is installed first.

```bash
conda install conda-build

conda build recipe/
```

--------------------------------

### Run Application (Windows)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/02_creating_your_applications.md

Executes the built application on Windows. Assumes the executable is located at 'momentum/examples/hello_world/build/Release/hello_world.exe'.

```bash
# Windows
momentum/examples/hello_world/build/Release/hello_world.exe
```

--------------------------------

### Install CMake Modules

Source: https://github.com/facebookresearch/momentum/blob/main/CMakeLists.txt

Installs specific CMake modules ('Findre2.cmake', 'FindFbxSdk.cmake') to the designated installation directory. These modules help CMake find external dependencies.

```cmake
install(
  FILES cmake/Findre2.cmake cmake/FindFbxSdk.cmake
  DESTINATION ${MOMENTUM_CONFIG_INSTALL_DIR}
)
```

--------------------------------

### Run Application (Linux/macOS)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/02_creating_your_applications.md

Executes the built application on Linux or macOS. Assumes the executable is located at './momentum/examples/hello_world/build/hello_world'.

```bash
# Linux and macOS
./momentum/examples/hello_world/build/hello_world
```

--------------------------------

### Build Application (Windows)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/02_creating_your_applications.md

Builds the application using CMake on Windows after configuration. Assumes the build directory is 'momentum/examples/hello_world/build' and Release configuration.

```bash
# Windows
pixi run cmake --build momentum/examples/hello_world/build --config Release
```

--------------------------------

### Build and Test PyMomentum from Source

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_python/01_user_guide/01_getting_started.md

Build the project using the pixi run build command and then run the Python tests with pixi run test_py.

```bash
pixi run build

pixi run test_py
```

--------------------------------

### Build and Test Project

Source: https://github.com/facebookresearch/momentum/blob/main/CONTRIBUTING.md

Commands to build the C++ library and Python bindings, and run associated tests.

```bash
pixi run build        # C++ library
pixi run build_py     # Python bindings
```

```bash
pixi run test         # C++ tests
pixi run test_py      # Python tests
```

--------------------------------

### Run USD Viewer (OSS)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/01_viewers.md

Use the pixi run command to launch the USD viewer with an input file.

```bash
pixi run usd_viewer --input <my_file.usd>
```

--------------------------------

### Configure Camera Test

Source: https://github.com/facebookresearch/momentum/blob/main/CMakeLists.txt

Sets up the camera test, linking the camera library.

```cmake
mt_test(
  NAME camera_test
  SOURCES_VARS camera_test_sources
  LINK_LIBRARIES
    camera
  )

```

--------------------------------

### CMakeLists.txt for Library

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/02_creating_your_applications.md

Demonstrates how to configure CMake to build either a shared or static library that depends on Momentum. Links the library against momentum::math.

```cmake
add_library(my_lib SHARED my_lib.hpp my_lib.cpp)  # shared
add_library(my_lib STATIC my_lib.hpp my_lib.cpp)  # static
target_link_libraries(my_lib PUBLIC momentum::math)
```

--------------------------------

### Build Application (Linux/macOS)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/02_creating_your_applications.md

Builds the application using CMake on Linux or macOS after configuration. Assumes the build directory is 'momentum/examples/hello_world/build'.

```bash
# Linux and macOS
pixi run cmake --build momentum/examples/hello_world/build
```

--------------------------------

### Run GLB Viewer (OSS)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/01_viewers.md

Use the pixi run command to launch the GLB viewer with an input file.

```bash
pixi run glb_viewer --input <my_file.glb>
```

--------------------------------

### Configure USD I/O Test

Source: https://github.com/facebookresearch/momentum/blob/main/CMakeLists.txt

Sets up the test for USD I/O, including Python 3 linkage and resource path environment variable.

```cmake
mt_test(
  NAME io_usd_test
  SOURCES_VARS io_usd_test_sources
  LINK_LIBRARIES
    character_test_helpers
    io_usd
    io_test_helper
    Python3::Python
  ENV
    "TEST_RESOURCES_PATH=${CMAKE_SOURCE_DIR}/momentum/test/resources"
  )

```

--------------------------------

### Activate Conda Environment

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_python/01_user_guide/01_getting_started.md

Activate your target conda environment before proceeding with the installation.

```bash
conda activate your_environment_name
```

--------------------------------

### Generate and Inspect PyPI Configurations Locally

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_python/03_developer_guide/03_pypi_publishing.md

Execute local commands to generate PyPI configuration files and inspect the generated CPU and GPU constraints.

```bash
pixi run generate_pyproject
cat pyproject-pypi-cpu.toml    # Check CPU constraints
cat pyproject-pypi-gpu.toml    # Check GPU constraints
```

--------------------------------

### Run Process Markers with Calibration Config

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/02_process_markers.md

Use this command to calibrate the skeleton and marker layout, then track motion data. Requires a configuration file.

```bash
pixi run process_markers -c process_markers_calib.config
```

```bash
buck run @arvr/mode/win/opt process_markers_app -- -c process_markers_calib.config
```

--------------------------------

### Run Process Markers with Tracking Config

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/02_process_markers.md

Use this command to track motion data using a pre-calibrated model. Requires a configuration file.

```bash
pixi run process_markers -c process_markers_tracking.config
```

```bash
buck run @arvr/mode/win/opt process_markers_app -- -c process_markers_tracking.config
```

--------------------------------

### Run FBX Viewer (OSS)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/01_viewers.md

Use the pixi run command to launch the FBX viewer with an input file.

```bash
pixi run fbx_viewer --input <my_file.fbx>
```

--------------------------------

### Run FBX Viewer (Internal)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/01_viewers.md

Use the buck run command to launch the FBX viewer with an input file in an internal environment.

```bash
buck run @arvr/mode/win/opt fbx_viewer -- --input <my_file.fbx>
```

--------------------------------

### Troubleshoot Test Failures

Source: https://github.com/facebookresearch/momentum/blob/main/CONTRIBUTING.md

Use verbose test output to get detailed information for debugging failing tests.

```bash
pixi run test_verbose
```

--------------------------------

### Run USD Viewer (Internal)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/01_viewers.md

Use the buck run command to launch the USD viewer with an input file in an internal environment.

```bash
buck run @arvr/mode/win/opt usd_viewer -- --input <my_file.usd>
```

--------------------------------

### Run refine_motion with Config (OSS)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/04_refine_motion.md

Execute the refine_motion tool using pixi and a specified configuration file. This is the standard way to run the tool in an open-source environment.

```bash
pixi run refine_motion -c refine_motion.config
```

--------------------------------

### Build Static Website Content

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/README.md

Generates static website content into the 'build' directory, ready for hosting.

```bash
$ yarn build
```

--------------------------------

### Run GLB Viewer (Internal)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/01_viewers.md

Use the buck run command to launch the GLB viewer with an input file in an internal environment.

```bash
buck run @arvr/mode/win/opt glb_viewer -- --input <my_file.glb>
```

--------------------------------

### Run C3D Viewer (OSS)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/01_viewers.md

Use the pixi run command to launch the C3D viewer with an input file.

```bash
pixi run c3d_viewer --input <my_file.c3d>
```

--------------------------------

### Find PyTorch Packages

Source: https://github.com/facebookresearch/momentum/blob/main/pymomentum/CMakeLists.txt

Locates the ATen and Torch CMake configuration packages. It searches in standard locations for both conda and PyPI installations.

```cmake
# Try both locations for CMake files (conda and PyPI have different structures)
find_package(ATen CONFIG REQUIRED HINTS
  ${libtorch_base_path}/share/cmake/ATen
  ${libtorch_base_path}
)
find_package(Torch CONFIG REQUIRED HINTS
  ${libtorch_base_path}/share/cmake/Torch
  ${libtorch_base_path}
)
```

--------------------------------

### Clean Momentum Build Artifacts

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/01_getting_started.md

Remove build artifacts and the Pixi virtual environment to start over. This cleans the 'build/' directory and '.pixi/'.

```bash
pixi run clean
```

--------------------------------

### Open Project in Visual Studio

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/04_developer_guide/01_development_environment.md

Opens the Momentum project in Microsoft Visual Studio 2022 on Windows using Pixi.

```bash
pixi run open_vs
```

--------------------------------

### Create and Configure Camera

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_python/02_examples/02_visualization_pymomentum_rasterizer.md

Demonstrates how to create a camera with a pinhole intrinsics model and set its extrinsics using look_at and frame methods. This is useful for defining the viewpoint and framing objects in the scene.

```python
import pymomentum.camera as pym_camera
import pymomentum.renderer as pym_renderer
import numpy as np

image_height, image_width = 800, 1000

# Create a pinhole intrinsics model
intrinsics = pym_camera.PinholeIntrinsicsModel(
    image_width=image_width,
    image_height=image_height,
    fx=800.0,  # focal length in pixels
    fy=800.0,
    cx=image_width / 2.0,  # principal point
    cy=image_height / 2.0
)

# Create a camera with the intrinsics
camera = pym_camera.Camera(intrinsics)

# Move the camera along -z and look at the origin
camera = camera.look_at(
    position=np.array([0, 0, 1]), target=np.zeros(3), up=np.array([0, 1, 0])
)

# Make sure the entire object is in view:
camera = camera.frame(vertex_positions)
```

--------------------------------

### Include Public Momentum Headers

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/04_developer_guide/02_style_guide.md

In public Momentum header files, use angle brackets for includes. This ensures that downstream users can find these headers in their system include paths after installation.

```cpp
// In public header files (e.g., momentum/character/character.h)
#include <momentum/common/checks.h>
#include <momentum/math/mesh.h>
```

--------------------------------

### Basic C++ Source Code

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/02_creating_your_applications.md

A simple C++ program that includes the Momentum mesh header and creates a Mesh object. This serves as a starting point for applications using Momentum's math functionalities.

```cpp
#include <momentum/math/mesh.h>

using namespace momentum;

int main() {
  auto mesh = Mesh();
  mesh.updateNormals();
  return EXIT_SUCCESS;
}
```

--------------------------------

### Run refine_motion with Config (Internal)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/04_refine_motion.md

Execute the refine_motion tool using buck run with a specific mode for Windows. This command is intended for internal Facebook/Meta development environments.

```bash
buck run @arvr/mode/win/opt refine_motion -- -c refine_motion.config
```

--------------------------------

### Configure CMake Project (Windows)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/02_creating_your_applications.md

Configures the CMake build for a project on Windows. Assumes the project root is at 'momentum/examples/hello_world/'.

```bash
# Windows
pixi run cmake -S momentum/examples/hello_world -B momentum/examples/hello_world/build
```

--------------------------------

### Standard CMake Build Options

Source: https://github.com/facebookresearch/momentum/blob/main/CMakeLists.txt

Defines various build options for Momentum, such as USD I/O, Python bindings, testing, examples, Rerun visualization, profiling, and SIMD instructions. These are typically set to OFF by default unless specified otherwise.

```cmake
mt_option(MOMENTUM_BUILD_IO_USD "Build USD I/O support" OFF)
mt_option(MOMENTUM_BUILD_PYMOMENTUM "Build Python binding" OFF)
mt_option(MOMENTUM_BUILD_TESTING "Enable building tests" OFF)
mt_option(MOMENTUM_BUILD_EXAMPLES "Enable building examples" OFF)
mt_option(MOMENTUM_BUILD_RERUN "Build native Rerun C++ visualization support" ON)
mt_option(MOMENTUM_ENABLE_PROFILING "Enable building with profiling annotations" OFF)
mt_option(MOMENTUM_ENABLE_SIMD "Enable building with SIMD instructions" ON)
mt_option(MOMENTUM_INSTALL_EXAMPLES "Install examples" OFF)
mt_option(MOMENTUM_USE_SYSTEM_GOOGLETEST "Use GoogleTest installed in system" OFF)
mt_option(MOMENTUM_USE_SYSTEM_MDSPAN "Use mdspan installed in system" OFF)
mt_option(MOMENTUM_USE_SYSTEM_PYBIND11 "Use pybind11 installed in system" OFF)
mt_option(MOMENTUM_USE_SYSTEM_RERUN_CPP_SDK "Use Rerun C++ SDK installed in system" OFF)
mt_option(MOMENTUM_USE_SYSTEM_TRACY "Use Tracy installed in system" OFF)
```

--------------------------------

### Build Python Bindings

Source: https://github.com/facebookresearch/momentum/blob/main/CONTRIBUTING.md

Commands to build Python bindings, run Python tests, and build Python documentation.

```bash
pixi run build_py      # Build Python bindings
pixi run test_py       # Run Python tests
pixi run doc_py        # Build Python docs
```

--------------------------------

### Build C++ Library

Source: https://github.com/facebookresearch/momentum/blob/main/CONTRIBUTING.md

Commands for building the C++ library in release or debug mode, and running tests.

```bash
pixi run build         # Release build
pixi run build_dev     # Debug build
pixi run test          # Run tests
```

--------------------------------

### Refine Motion with Config and Overrides (Internal)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/04_refine_motion.md

Execute the refine_motion tool using buck run, specifying a Windows mode, and overriding input, output, and smoothing parameters. This is for internal development workflows.

```bash
buck run @arvr/mode/win/opt refine_motion -- -c refine_motion.config -i track.glb -o refined.glb --smoothing 2.5
```

--------------------------------

### Run C3D Viewer (Internal)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/01_viewers.md

Use the buck run command to launch the C3D viewer with an input file in an internal environment.

```bash
buck run @arvr/mode/win/opt c3d_viewer -- --input <my_file.c3d>
```

--------------------------------

### Set up TorchBridge Include Directory

Source: https://github.com/facebookresearch/momentum/blob/main/pymomentum/CMakeLists.txt

Configures the include directory for the TorchBridge interface library and creates the necessary directory structure. This is typically used for OSS builds.

```cmake
set(TORCH_BRIDGE_INCLUDE_DIR ${CMAKE_CURRENT_BINARY_DIR}/torch_bridge_include)
file(MAKE_DIRECTORY ${TORCH_BRIDGE_INCLUDE_DIR}/pymomentum)
configure_file(
  ${CMAKE_CURRENT_SOURCE_DIR}/oss/torch_bridge.h.in
  ${TORCH_BRIDGE_INCLUDE_DIR}/pymomentum/torch_bridge.h
  COPYONLY
)
```

--------------------------------

### Run BVH Viewer (OSS)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/01_viewers.md

Use the pixi run command to launch the BVH viewer with an input file.

```bash
pixi run bvh_viewer --input <my_file.bvh>
```

--------------------------------

### Build Test Wheels Locally

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_python/03_developer_guide/03_pypi_publishing.md

Commands to clean previous build artifacts, build PyPI wheels for a specific Python version, and check the built wheel.

```bash
pixi run -e py312 clean_dist
pixi run -e py312 build_pypi_wheel
pixi run -e py312 check_pypi
```

--------------------------------

### Refine Motion with Config and Overrides (OSS)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/04_refine_motion.md

Run the refine_motion tool with a configuration file and override specific parameters like input, output, and smoothing factor via command-line arguments. Suitable for open-source usage.

```bash
pixi run refine_motion -c refine_motion.config -i track.glb -o refined.glb --smoothing 2.5
```

--------------------------------

### Run All Tests

Source: https://github.com/facebookresearch/momentum/blob/main/CONTRIBUTING.md

Commands to execute all C++ and Python tests, including verbose output options.

```bash
pixi run test              # C++ tests
pixi run test_py           # Python tests
pixi run test_verbose      # C++ verbose output
pixi run test_py_verbose   # Python verbose output
```

--------------------------------

### Run URDF Viewer (OSS)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/01_viewers.md

Use the pixi run command to launch the URDF viewer with an input file.

```bash
pixi run urdf_viewer --input <my_file.urdf>
```

--------------------------------

### Configure Glove Utilities Test

Source: https://github.com/facebookresearch/momentum/blob/main/CMakeLists.txt

Sets up the glove utilities test, linking character test helpers and marker tracker libraries.

```cmake
mt_test(
  NAME glove_utils_test
  SOURCES_VARS glove_utils_test_sources
  LINK_LIBRARIES
    character_test_helpers
    marker_tracker
  )

```

--------------------------------

### Configure CMake Project (Linux/macOS)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/02_creating_your_applications.md

Configures the CMake build for a project on Linux or macOS. Assumes the project root is at 'momentum/examples/hello_world/'.

```bash
# Linux and macOS
pixi run cmake -S momentum/examples/hello_world -B momentum/examples/hello_world/build -DCMAKE_BUILD_TYPE=Release
```

--------------------------------

### Convert FBX Animation to GLB with Model Parameters

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/03_convert_model.md

Converts an FBX animation file to GLB format, using a specified model parameter file for mapping. Note that the conversion may not be lossless and uses InverseParameterTransform for parameter fitting.

```bash
pixi run convert_model -d animation.fbx -p character.model -o animation.glb
```

```bash
buck run @arvr/mode/win/opt convert_model -- -d animation.fbx -p character.model -o animation.glb
```

--------------------------------

### Run URDF Viewer (Internal)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/01_viewers.md

Use the buck run command to launch the URDF viewer with an input file in an internal environment.

```bash
buck run @arvr/mode/win/opt urdf_viewer -- --input <my_file.urdf>
```

--------------------------------

### Troubleshoot Build Failures

Source: https://github.com/facebookresearch/momentum/blob/main/CONTRIBUTING.md

Commands to clean the build and rebuild the project to resolve build failures.

```bash
pixi run clean && pixi run build
```

--------------------------------

### Create Depth and RGB Buffers

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_python/02_examples/02_visualization_pymomentum_rasterizer.md

Create z_buffer and rgb_buffer using the camera object. The buffer size is padded to the nearest multiple of 8 for SIMD performance.

```python
import pymomentum.renderer as pym_renderer
z_buffer = pym_renderer.create_z_buffer(camera)
rgb_buffer = pym_renderer.create_rgb_buffer(camera)
```

--------------------------------

### Print Build Options

Source: https://github.com/facebookresearch/momentum/blob/main/CMakeLists.txt

Calls a CMake function to print the currently configured build options. This is useful for verifying the build configuration.

```cmake
mt_print_options()
```

--------------------------------

### Run BVH Viewer (Internal)

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/03_examples/01_viewers.md

Use the buck run command to launch the BVH viewer with an input file in an internal environment.

```bash
buck run @arvr/mode/win/opt bvh_viewer -- --input <my_file.bvh>
```

--------------------------------

### Configure Legacy JSON I/O Test

Source: https://github.com/facebookresearch/momentum/blob/main/CMakeLists.txt

Sets up the test for legacy JSON I/O, specifying source variables, linked libraries, and environment paths.

```cmake
mt_test(
  NAME io_legacy_json_test
  SOURCES_VARS io_legacy_json_test_sources
  LINK_LIBRARIES
    character_test_helpers
    io_legacy_json
    io_test_helper
  ENV
    "TEST_RESOURCES_PATH=${CMAKE_SOURCE_DIR}/momentum/test/resources"
  )

```

--------------------------------

### Generate Video Frame by Frame

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_python/02_examples/02_visualization_pymomentum_rasterizer.md

Demonstrates how to render individual frames and write them to a video file using OpenCV. Ensure the image buffer is converted from RGB to BGR for OpenCV compatibility.

```python
import cv2

# Initialize video writer
fourcc = cv2.VideoWriter_fourcc(*'mp4v')
video_writer = cv2.VideoWriter(file_path, fourcc, video_fps, (video_width, video_height))

for i_frame in range(n_frames):
    full_image = np.zeros(shape=(video_height, video_width, 3), dtype=np.uint8)
    # ... render your frame ...
    # Convert RGB to BGR for OpenCV
    bgr_image = full_image[..., ::-1]
    video_writer.write(bgr_image)

video_writer.release()
```

--------------------------------

### Run export_objs with buck

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/examples/export_objs/README.md

Execute the export_objs utility using buck2. Specify the input animation file and the output folder for OBJ files. Optional arguments for frame range and stride can be provided.

```bash
buck2 run path/to/momentum/examples:export_objs -- \
  -i <input_file> \
  -o <output_folder> \
  [--first <frame_number>] \
  [--last <frame_number>] \
  [--stride <frame_stride>]
```

--------------------------------

### Antialiasing with Supersampling in PyMomentum

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_python/02_examples/02_visualization_pymomentum_rasterizer.md

Demonstrates how to implement antialiasing by supersampling the camera and then downsampling the output. This improves visual quality, especially for thin structures.

```python
import pymomentum.renderer as pym_renderer
sup_samp: int = 2
cam_supersample = cam.upsample(sup_samp)
z_buffer = pym_renderer.create_z_buffer(cam_supersample)
rgb_buffer = pym_renderer.create_rgb_buffer(cam_supersample)

# render
pym_renderer.rasterize_mesh(...)

output_image = np.zeros(shape=(cam.image_height, cam.image_width, 3))
# Alpha_matte function knows how to handle alpha with upsampled cameras (will
# correctly blend along edges using the averaged alpha).
pym_renderer.alpha_matte(z_buffer, rgb_buffer, output_image)
```

--------------------------------

### Export all frames from GLB with buck

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/examples/export_objs/README.md

Export all animation frames from a GLB file to a specified output folder using buck2.

```bash
buck2 run path/to/momentum/examples:export_objs -- \
  -i test.glb \
  -o /tmp/exported_objs
```

--------------------------------

### Configure USD glTF Roundtrip Test

Source: https://github.com/facebookresearch/momentum/blob/main/CMakeLists.txt

Sets up the test for USD glTF roundtrip functionality, linking necessary helper and I/O libraries, including Python 3.

```cmake
mt_test(
  NAME io_usd_gltf_roundtrip_test
  SOURCES_VARS io_usd_gltf_roundtrip_test_sources
  LINK_LIBRARIES
    character_test_helpers
    character_test_helpers_gtest
    io_gltf
    io_test_helper
    io_usd
    Python3::Python
)

```

--------------------------------

### Test Momentum Build

Source: https://github.com/facebookresearch/momentum/blob/main/momentum/website/docs_cpp/02_user_guide/01_getting_started.md

Run the test suite for the Momentum C++ project after building.

```bash
pixi run test
```

--------------------------------

### Feature Branch Workflow

Source: https://github.com/facebookresearch/momentum/blob/main/CONTRIBUTING.md

Steps for creating a feature branch, making changes, linting, and testing before committing.

```bash
git checkout -b feature/your-feature
# Make your changes
pixi run lint         # Format code
pixi run test         # Verify tests pass
```

--------------------------------

### Configure Marker Gap Fill Test

Source: https://github.com/facebookresearch/momentum/blob/main/CMakeLists.txt

Sets up the marker gap fill test, linking character test helpers and marker tracker libraries.

```cmake
mt_test(
  NAME marker_gap_fill_test
  SOURCES_VARS marker_gap_fill_test_sources
  LINK_LIBRARIES
    character_test_helpers
    marker_tracker
  )

```