guc is a glTF to Universal Scene Description (USD) converter.
Unlike...
guc furthermore supports near-lossless material translation via the MaterialX standard.
All glTF features except animation and skinning are implemented and get continuously tested in guc's test suite.
Wayfair's Iridescent Dish with Olives (CC BY) converted to USD+MaterialX with guc and rendered in hdStorm (left). The same model in Khronos's glTF Sample Viewer (right).
You need USD v23.11+ (e.g. v24.05) with MaterialX support enabled.
Do a recursive clone of the repository and set up a build folder:
git clone https://github.com/pablode/guc --recursive
mkdir guc/build && cd guc/build
Pass following parameters in the CMake generation phase:
cmake .. -Wno-dev -DCMAKE_BUILD_TYPE=Release
Build the executable:
cmake --build . -j8 --config Release
Note: set
BUILD_SHARED_LIBS
for shared builds, andCMAKE_MSVC_RUNTIME_LIBRARY
to USD's MSVC ABI.
guc 0.4 - glTF to USD converter
Usage: guc [options] [--] <gltf_path> <usd_path>
Options:
-m, --emit-mtlx Emit MaterialX materials in addition to UsdPreviewSurfaces
-u, --mtlx-as-usdshade Convert and inline MaterialX materials into the USD layer using UsdMtlx
-c, --hdstorm-compat Apply compatibility tweaks for the USD Storm Hydra render delegate
-v, --default-material-variant=<index> Index of the material variant that is selected by default
-l, --licenses Print the license of guc and third-party libraries
-h, --help Show the command help
Both glTF and GLB file types are valid input. USDA, USDC and USDZ formats can be written.
An example asset conversion is described in the Structure Mapping document.
Name | Status |
---|---|
KHR_lights_punctual | ✅ Partial 1 |
KHR_materials_clearcoat | ✅ Complete |
KHR_materials_emissive_strength | ✅ Complete |
KHR_materials_ior | ✅ Complete |
KHR_materials_iridescence | ✅ Complete |
KHR_materials_sheen | ✅ Complete |
KHR_materials_specular | ✅ Complete |
KHR_materials_transmission | ✅ Complete |
KHR_materials_unlit | ✅ Complete |
KHR_materials_variants | ✅ Complete |
KHR_materials_volume | ✅ Partial 2 |
KHR_texture_transform | ✅ Complete |
[1] Spotlight cone falloff is ignored.
[2] Thickness is not supported by the MaterialX glTF PBR implementation.
The usdGlTF library implements USD's Sdf file format interface. Enable the GUC_BUILD_USDGLTF
CMake option before building and install it as follows:
cmake --install . --component usdGlTF --config Release --prefix <USD_INSTALL_DIR>/plugin/usd
glTF files can now be referenced as layers and opened with USD tooling. The emitMtlx dynamic Sdf file format argument controls MaterialX material emission.
Copyright 2024 Pablo Delgado Krämer
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.