Initial implementation of MuJoCo Live.

This is a combination of minor tweaks to the existing Studio WASM application, CMake cleanup to make it buildable, and integration with GitHub Actions for deployment.

The new features added are drag-and-drop, model specification through `?model=` URL parameter, HTTP and HTTPS resource provider, and a user-visible loading message while the model is loading.

PiperOrigin-RevId: 904594610
Change-Id: I3a73b1ca0fcd6fc9ba192469942b2dab010a9308

cmake/MujocoOptions.cmake

@@ -18,7 +18,11 @@ set(CMAKE_C_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
-set(CMAKE_C_EXTENSIONS OFF)
+if(EMSCRIPTEN)
+  set(CMAKE_C_EXTENSIONS ON)
+else()
+  set(CMAKE_C_EXTENSIONS OFF)
+endif()
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON) # For LLVM tooling
 
 if(NOT CMAKE_CONFIGURATION_TYPES)

cmake/third_party_deps/filament.cmake

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 set(MUJOCO_DEP_VERSION_filament
-    a4945939de514d049baeed654efbbdd06bc5bdbf
+    06793c4a80dd467025b2db1b3b7ea63bf1a865bb
     CACHE STRING "Tag/version of `filament` to be fetched."
 )
 mark_as_advanced(MUJOCO_DEP_VERSION_filament)
@@ -23,6 +23,15 @@ include(FindOrFetch)
 set(BUILD_SHARED_LIBS_OLD ${BUILD_SHARED_LIBS})
 set(BUILD_SHARED_LIBS OFF)
 
+# Filament's ShaderMinifier.cpp uses strlen without including <cstring>, and
+# PostProcessManager.h uses std::optional without including <optional>.
+set(CMAKE_CXX_FLAGS_OLD "${CMAKE_CXX_FLAGS}")
+if(MSVC)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /FI cstring /FI optional")
+else()
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -include cstring -include optional")
+endif()
+
 set(FILAMENT_ENABLE_EXPERIMENTAL_GCC_SUPPORT ON)
 set(FILAMENT_SKIP_SDL2 ON)
 set(FILAMENT_USE_EXTERNAL_ABSL ON)
@@ -39,3 +48,4 @@ fetchpackage(
 )
 
 set(BUILD_SHARED_LIBS ${BUILD_SHARED_LIBS_OLD})
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS_OLD}")