Animation Export strategy

[Ennosch]

Animation Export

Is there a way to determine the root primitive when using the the cmds.file or cmds.mayaUSDExport command ?
Or is there a way to only export a section from maya to a .usd file ?

For example:

Given this maya hierarchy:

the goal would be a .usd file that looks like this:
(note the defaultPrim = "testoid" here)

#usda 1.0
(
    defaultPrim = "testoid"
    metersPerUnit = 0.01
    upAxis = "Y"
)

def Xform "testoid" (
    kind = "component"
)
{
    def Mesh "testoid_body_geo"
    {
        ...
    }

    def Mesh "testoid_head_geo"
    {
        ...
    }
}

However with both cmds.file and cmds.mayaUSDExport the translators always export the nodes parent DAG node as the root primitive. Even with a flag like
exportSelected = 1
selection = True

Using cmds.file function like this:

import maya.cmds as cmds

kwargs = {
    "-options" :
        "\
exportUVs=0;\
exportColorSets=0;\
defaultMeshScheme=catmullClark;\
defaultUSDFormat=usda;\
animation=0;\
eulerFilter=0;\
startTime=1;\
endTime=1;\
frameStride=1;\
frameSample=0.0;\
parentScope=;\
exportDisplayColor=0;\
shadingMode=none;\
exportInstances=0;\
exportVisibility=1;\
mergeTransformAndShape=1;\
stripNamespaces=1\
",
    "-typ" : "USD Export",
    "-preserveReferences" : 1,
    "-exportSelected" : 1,
}

cmds.select("testoid")
mfile = "/tmp/export_test/export_1.usda"
cmds.file(mfile, **kwargs)

cmds.file output:

#usda 1.0
(
    defaultPrim = "rig"
    metersPerUnit = 0.01
    upAxis = "Y"
)

def Xform "rig" (
    kind = "component"
)
{
    def Xform "geo"
    {
        def Xform "testoid"                              # <------ we want this to be the root primitive not "rig"
        {
            def Mesh "testoid_body_geo"
            {
                ...
            }

            def Mesh "testoid_head_geo"
            {
                ...
            }
        }
    }
}

Using cmds.mayaUSDExport function like this:

import maya.cmds as cmds

cmds.select("testoid")
mfile = "/tmp/export_test/export_2.usda"
kwargs = {
    "selection" : 1,
    "f": mfile,
    "frameRange" : (1,25)
}
cmds.mayaUSDExport(mfile, **kwargs)

cmds.mayaUSDExport output:

#usda 1.0
(
    defaultPrim = "rig"
    endTimeCode = 25
    framesPerSecond = 24
    metersPerUnit = 0.01
    startTimeCode = 1
    timeCodesPerSecond = 24
    upAxis = "Y"
)

def Xform "rig" (
    kind = "component"
)
{
    def Xform "geo"
    {
        def Xform "testoid"                              # <------ we want this to be the root primitive not "rig"
        {
            def Mesh "testoid_body_geo" (
                prepend apiSchemas = ["MaterialBindingAPI"]
            )
            {
                ...
            }

            def Mesh "testoid_head_geo" (
                prepend apiSchemas = ["MaterialBindingAPI"]
            )
            {
                ...
            }
        }
    }

    def Scope "Looks"
    {
        def Material "initialShadingGroup"
        {
        }
    }
}

[kxl-adsk]

We have an open PR that adds this functionality - please have a look at #1111

[Ennosch]

That's great @kxl-adsk
Thank you