Tiny USD

A tutorial on creating the smallest possible viable USD program, using the dev branch of the official usd distribution.

In the spirit of minimalism, it skips Hydra, and Python bindings.

Prerequisites

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• git
• cmake 3.26 or greater installed for the command line
• Xcode command line tools, tested with Apple Clang 14

Building

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Shallow clone the USD dev branch into this project's packages directory:

cd tinyusd
mkdir packages
cd packages
git clone --depth 1 https://github.com/PixarAnimationStudios/USD.git -b dev

boost

Fetch boost and unarchive it. Boost will not be built, the headers as is are sufficient.

./get_boost.sh

tbb

Fetch and build tbb. In the root directory:

./get_tbb.sh

OpenSubdiv

If you are building USD with Hydra, you'll need OpenSubdiv.

./get_opensubdiv.sh

Configure USD

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Once again, starting in the packages directory:

mkdir usd-build;cd usd-build

We are going to build USD without python, as python adds complexity, by requiring that boost python be built.

First, configure the build, from within the usd-build directory.

In the command below, replace the PREFIX and TOOLCHAIN variable values with appropriate paths.

with Hydra

cmake -DPXR_ENABLE_PYTHON_SUPPORT=OFF -DPXR_BUILD_MONOLITHIC=ON -DPXR_BUILD_DOCUMENTATION=OFF -DPXR_BUILD_TESTS=OFF -DCMAKE_INSTALL_PREFIX=..  -G "Xcode" ../USD

without Hydra

cmake -DPXR_ENABLE_PYTHON_SUPPORT=OFF -DPXR_BUILD_MONOLITHIC=ON -DPXR_BUILD_DOCUMENTATION=OFF -DPXR_BUILD_TESTS=OFF -DPXR_BUILD_IMAGING=OFF -DCMAKE_INSTALL_PREFIX=..  -G "Xcode" ../USD

Build USD

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cmake --build . --config Release --target install

Finish up the installation

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In a little while, packages/lib will contain the libusd_ms.dylib, and packages/include will have the headers, packages/bin will have sdfdump and sdffilter.

Double check your work

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There is an executable in the bin directory called sdfdump. Running it should result in the executable describing its input arguments, without any complaints of missing dylibs.

TinyUsd

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Go back into the packages directory we made earlier, and create a tinyusd-build directory, and cd into it.

mkdir tinyusd-build;cd tinyusd-build

Then, configure the cmake build files. Once again, make sure the INSTALL_PREFIX and TOOLCHAIN variables are pointed appropriately.

cmake -G "Xcode" ../.. -DCMAKE_INSTALL_PREFIX=.. -DCMAKE_PREFIX_PATH=..

Build tinyusd.

cmake --build . --config Release --target install

Haven't got the rpath installation set up correctly in the cmake file yet, so go to the bin directory, and add it.

cd ../bin
install_name_tool -add_rpath ../lib tinyusd

Now, run tinyusd.

./tinyusd

Sanity check that tinyusd generated a file named test.usd, containing the following:

#usda 1.0

def Cube "Box"
{
    float3 xformOp:scale = (5, 5, 5)
    uniform token[] xformOpOrder = ["xformOp:scale"]
}