UsdAbc : Alembic File Format Plugin

Overview

This library currently exists to provide the alembic file format plugin for USD, and currently has no user-level API.

Behavior

SDF_FORMAT_ARGS

UsdAbc accepts some SDF_FORMAT_ARGS for controlling behavior.

SDF_FORMAT_ARGS Meaning Default Value
abcReRoot=STRING 'ReRoot' the immediate children of the IArchive on a single Xform whose name is the value of STRING empty / ""
abcLayers=LAYER_1,LAYER_2,LAYER_N Additional / Layered alembic files for IFactory::getArchive.
These are expected as paths already resolved (likely absolute)
empty / []

testenv/testUsdAbcSDFArguments/testUsdAbcSDFArguments.usda has the following example, which will load all children in testUsdAbcSDFArgumentsMesh.abc into the 'AlembicRoot' Xform, using layered Alembic to load UVs from testUsdAbcSDFArgumentsUV.abc.

def Xform "AlembicRoot" (
    references = @./testUsdAbcSDFArgumentsMesh.abc:SDF_FORMAT_ARGS:abcReRoot=AlembicRoot&abcLayers=./testUsdAbcSDFArgumentsUV.abc@
)
{
}

TfEnvSettings

UsdAbc exposes some TfEnvSettings for controlling behavior.

Setting Name Meaning Default Value
USD_ABC_NUM_OGAWA_STREAMS The number of threads available for reading ogawa-backed files. 4
USD_ABC_EXPAND_INSTANCES Force alembic instances to be expanded false
USD_ABC_DISABLE_INSTANCES Disable instancing on prototypes created from alembic false
USD_ABC_PARENT_INSTANCES Make parent of instance source into prototypes where possible true
USD_ABC_WARN_ALL_UNSUPPORTED_VALUES Issue warnings for all unsupported values encountered. false