Page Comparison

0. Legal requirements

1. Build system changes

Add Dockerfile to standardize Emscripten build (using an Ubunutu 22.04 LTS base image)

• • Using known good Emscripten version (2.0.24)

Update build_usd.py build script to support:

Adding an --emscripten build option to specify a WebAssembly target

Potential to replace "–-emscripten" with "–-wasm"? Decision TBD.

https://github.com/autodesk-forks/USD/blob/adsk/feature/webgpu/build_scripts/build_usd.py#L2198

Using emcmake/emmake as a drop-in replacement for cmake when targeting WebAssembly build

Replacing TBB with WasmTBB

Listing USD components incompatible with WebAssembly build to warn Users that Python, usdview, imaging have been disabled

Add CMakeLists.txt for JavaScript/WebAssembly bindings in order to:

• • List USD binding dependencies (usd, usdLux, usdGeom, usdUtils, sdf, tf)
  • Specify location of WebAssembly build artifacts (WASM bundle, WebWorker, JavaScript bindings)

Include tests to validate WebAssembly build, using a NodeJS dependency in order to enable tests from headless environments. Test examples include (but are not limited to):

1. 1. Loading a USDA stage
   2. Exporting USDA stage to string
   3. Traversing the USDA stage
   4. Running WebWorkers
   5. etc.

2. Core USD changes

arch library

• Add #if defined(__EMSCRIPTEN__) guards to integrate Emscripten as an alternative to Linux platform:

pxr/base/arch/debugger.cpp

• • ArchDebuggerTrap()

• •  ArchAbort()
  •  ARCH_BITS_32

https://github.com/autodesk-forks/USD/blob/adsk/feature/webgpu/pxr/base/arch/debugger.cpp#L597

https://github.com/autodesk-forks/USD/blob/adsk/feature/webgpu/pxr/base/arch/debugger.cpp#L646

Note sure what to do with ARCH_BITS_32

pxr/base/arch/fileSystem.cpp


• • ArchStatIsWritable()

• • ArchGetModificationTime()

• • ArchGetAccessTime()

• • ArchGetStatusChangeTime()

• • ArchGetFileLength()

https://github.com/autodesk-forks/USD/blob/adsk/feature/webgpu/pxr/base/arch/fileSystem.cpp#L162

https://github.com/autodesk-forks/USD/blob/adsk/feature/webgpu/pxr/base/arch/fileSystem.cpp#L199

https://github.com/autodesk-forks/USD/blob/adsk/feature/webgpu/pxr/base/arch/fileSystem.cpp#L456

https://github.com/autodesk-forks/USD/blob/adsk/feature/webgpu/pxr/base/arch/fileSystem.cpp#L469

https://github.com/autodesk-forks/USD/blob/adsk/feature/webgpu/pxr/base/arch/fileSystem.cpp#L501

https://github.com/autodesk-forks/USD/blob/adsk/feature/webgpu/pxr/base/arch/debugger.cpp#L660

pxr/base/arch/library.cpp

• ArchLibraryOpen()
•  ArchLibraryError()
• ArchLibraryClose()
• ArchLibraryGetSymbolAddress()

• ArchGetStartTickTime()
•  ArchGetStopTickTime()

https://github.com/autodesk-forks/USD/blob/adsk/feature/webgpu/pxr/base/arch/timing.h#L76

https://github.com/autodesk-forks/USD/blob/adsk/feature/webgpu/pxr/base/arch/timing.h#L133

• Consider options for running tests in a NodeJS runtime
• Include a few JavaScript tests demonstrating running tests of the arch lib built from Emscripten

Milestone: Share the code changes made up to this point with the greater USD community, seek feedback, framed around the changes up to this point as early end-to-end demo.

tf library

• Add type registration for USD symbols to be exposed to/from C++/JavaScript
  • Used to wrap TfToken, double, int, etc.
• Add TfPointerAndBits to specify operations on 32-bit architectures (as USD only specifies 64-bit operations by default)

vt library

• Add type registration for USD symbols to be exposed to/from C++/JavaScript
  • Add getJsObj to VtValue (similar to the existing getPyObj for Python)

sdf library

• Add type registration for USD symbols to be exposed to/from C++/JavaScript
  • Used to wrap SdfPath objects

usd library

• Add type registration for USD symbols to be exposed to/from C++/JavaScript
  • Used to wrap UsdPrim, UsdStage objects to expose CreateNew(), ExportToString() and other API bindings.

3. ThreeJS Hydra renderer