Add io_usd target for OpenUSD I/O support (#818)

Summary:
Adds `io_usd` target to CMake builds, enabling OpenUSD character I/O functionality.

**Key changes:**
- Add `io_usd` library with USD character loading/saving support
- Link `io_usd` to `io` target for unified I/O interface
- Add `io_usd_test` when testing is enabled
- Fix USD target names (use `usd`, `usdGeom`, `usdSkel` without `pxr::` prefix)
- Support dual USD initialization for internal/external builds
- Add TBB version compatibility (2019, 2020.3, 2021+)
- Fix `mt_python_library` to filter out non-file items from install lists

## Checklist:

- [x] Adheres to the style guidelines
- [x] Codebase formatted by running `pixi run lint`

Pull Request resolved: #818

Test Plan: `pixi run test` - All 20/20 C++ tests passed

Reviewed By: cstollmeta

Differential Revision: D87025592

Pulled By: jeongseok-meta

fbshipit-source-id: 1e655b79c916b8842d6830935957b7f57b1f9d56

Author: jeongseok-meta

CMakeLists.txt

@@ -117,8 +117,10 @@ find_package(fx-gltf CONFIG REQUIRED)
 find_package(indicators 2.3 CONFIG REQUIRED)
 find_package(nlohmann_json CONFIG REQUIRED)
 find_package(openfbx CONFIG REQUIRED)
+find_package(pxr CONFIG REQUIRED HINTS ${CMAKE_INSTALL_PREFIX} ${CMAKE_INSTALL_PREFIX}/cmake)
 find_package(re2 MODULE REQUIRED)
 find_package(spdlog CONFIG REQUIRED)
+find_package(TBB CONFIG REQUIRED)
 find_package(urdfdom CONFIG REQUIRED)
 
 if(MOMENTUM_BUILD_RENDERER)
@@ -448,6 +450,22 @@ mt_library(
     urdfdom::urdf_parser
 )
 
+mt_library(
+  NAME io_usd
+  HEADERS_VARS io_usd_public_headers
+  SOURCES_VARS io_usd_sources
+  PUBLIC_LINK_LIBRARIES
+    character
+    io_common
+    io_skeleton
+  PRIVATE_LINK_LIBRARIES
+    usd
+    usdGeom
+    usdSkel
+    TBB::tbb
+    Python3::Python  # Conda USD has Python symbols on both Linux and macOS
+)
+
 mt_library(
   NAME io_legacy_json
   HEADERS_VARS io_legacy_json_public_headers
@@ -493,6 +511,7 @@ mt_library(
     io_marker
     io_shape
     io_skeleton
+    io_usd
 )
 
 mt_library(
@@ -798,6 +817,18 @@ if(MOMENTUM_BUILD_TESTING)
       "TEST_RESOURCES_PATH=${CMAKE_SOURCE_DIR}/momentum/test/resources"
   )
 
+  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"
+  )
+
   mt_test(
     NAME rasterizer_test
     SOURCES_VARS rasterizer_test_sources

cmake/mt_defs.cmake

@@ -597,6 +597,16 @@ function(mt_python_library)
     mt_append_pymomentum_filelist("${var}" libs)
   endforeach()
 
+  # Filter out non-file items (e.g., library names that get incorrectly included)
+  # Only keep items that are actual files
+  set(filtered_libs "")
+  foreach(lib ${libs})
+    if(EXISTS "${lib}")
+      list(APPEND filtered_libs "${lib}")
+    endif()
+  endforeach()
+  set(libs "${filtered_libs}")
+
   if(NOT ${_ARG_NO_INSTALL})
     if(${_ARG_PRESERVE_DIRECTORY_STRUCTURE})
       # Store files with their directory structure preserved

momentum/io/usd/usd_io.cpp

@@ -34,9 +34,30 @@
 #include <pxr/usd/usdSkel/skinningQuery.h>
 
 #include <tbb/global_control.h>
-#include <tbb/task_scheduler_init.h>
 
+// TBB version compatibility:
+// - TBB 2019 and older: uses task_scheduler_init.h
+// - TBB 2020.3 and newer: uses global_control.h only (task_scheduler_init is deprecated)
+// - TBB 2021 and newer: task_scheduler_init.h completely removed
+#ifdef TBB_INTERFACE_VERSION
+#if TBB_INTERFACE_VERSION < 12000 // TBB 2020.3 has interface version 12000
+#include <tbb/task_scheduler_init.h>
+#define MOMENTUM_USE_TBB_TASK_SCHEDULER_INIT 1
+#endif
+#else
+// Try to include the header and define if successful
+#if __has_include(<tbb/task_scheduler_init.h>)
+#include <tbb/task_scheduler_init.h>
+#define MOMENTUM_USE_TBB_TASK_SCHEDULER_INIT 1
+#endif
+#endif
+
+// Conditional include for internal Meta environment vs open source
+// In open source builds, this header won't exist and MOMENTUM_WITH_USD_PLUGIN_INIT will be
+// undefined
+#ifdef MOMENTUM_WITH_USD_PLUGIN_INIT
 #include <UsdPluginInit.h>
+#endif
 
 #include <cstdio>
 #include <cstdlib>
@@ -48,6 +69,9 @@
 #include <thread>
 #include <vector>
 
+// Import USD namespace
+PXR_NAMESPACE_USING_DIRECTIVE
+
 namespace momentum {
 
 namespace {
@@ -83,22 +107,38 @@ std::mutex g_usdInitMutex;
 std::mutex g_usdOperationMutex;
 bool g_usdInitialized = false;
 std::unique_ptr<ResolverWarningsSuppressor> g_suppressor;
+#ifdef MOMENTUM_WITH_USD_PLUGIN_INIT
 std::unique_ptr<UsdPluginInit> g_usdPluginInit;
+#endif
 std::unique_ptr<tbb::global_control> g_tbbControl;
 
+// TBB compatibility variables for older versions
+#ifdef MOMENTUM_USE_TBB_TASK_SCHEDULER_INIT
+std::unique_ptr<tbb::task_scheduler_init> g_tbbTaskScheduler;
+#endif
+
 void initializeUsdWithSuppressedWarnings() {
   std::lock_guard<std::mutex> lock(g_usdInitMutex);
 
   if (g_usdInitialized) {
     return;
   }
 
+  // Initialize TBB with the appropriate method based on version
+#ifdef MOMENTUM_USE_TBB_TASK_SCHEDULER_INIT
+  // Use legacy task_scheduler_init for older TBB versions
+  g_tbbTaskScheduler = std::make_unique<tbb::task_scheduler_init>(1);
+#else
+  // Use modern global_control for newer TBB versions
   g_tbbControl =
       std::make_unique<tbb::global_control>(tbb::global_control::max_allowed_parallelism, 1);
+#endif
 
   g_suppressor = std::make_unique<ResolverWarningsSuppressor>();
   TfDiagnosticMgr::GetInstance().AddDelegate(g_suppressor.get());
 
+#ifdef MOMENTUM_WITH_USD_PLUGIN_INIT
+  // Internal Meta environment: Use UsdPluginInit for embedded plugins
   auto tempDir = filesystem::temp_directory_path();
 
   // Try a few fixed paths to avoid accumulating many plugin folders
@@ -122,6 +162,11 @@ void initializeUsdWithSuppressedWarnings() {
   } else {
     g_usdPluginInit = std::make_unique<UsdPluginInit>();
   }
+#else
+  // Open source environment: USD is already initialized via standard discovery
+  // The pxr package config automatically handles plugin paths via PXR_PLUGINPATH_NAME
+  MT_LOGI("USD I/O initialized with system USD installation");
+#endif
 
   g_usdInitialized = true;
 }