Get the current directory
import os
print(os.getcwd()) Change working directory
new_directory = <'/your/path/to/new/directory'>
os.chdir(new_directory) Note: For Google Colab only, use code below
from google.colab import files
files.download('your_file.usd')
import os
new_directory = <'/content/drive/My Drive/your_chosen_folder'>
os.chdir(new_directory) Create and save a Stage
from pxr import Usd, UsdGeom
stage = Usd.Stage.CreateNew("sphere.usda")
world_prim = UsdGeom.Xform.Define(stage, '/World')
xform_prim = UsdGeom.Xform.Define(stage, '/World/Xform')
sphere_prim = UsdGeom.Sphere.Define(stage, '/World/Sphere')
stage.Save() Open an existing .usd file
stage = Usd.Stage.Open("sphere.usda") 3.1.1 Viewing the Sphere¶
Print every prim path
for prim in stage.Traverse():
print(prim.GetPath().pathString) Retrieve prims
world_prim = stage.GetPrimAtPath('/World') List child prims
children_prims = world_prim.GetChildren()
for prim in children_prims:
print(prim.GetPath().pathString) Get parent prims
xform_prim = stage.GetPrimAtPath('/World/Xform')
parent_prim = xform_prim.GetParent() Remove a prim from a stage
successful = stage.RemovePrim('/World/Xform')
if successful:
print("/World/Xform has been removed") 3.3.2 Considering Directories & File Paths when Referencing¶
Setting working directory
Note: Make sure the new ‘blocks.usda’ is located in your ‘Ch03’ directory
import os
new_directory = <'/your/path/to/Ch03'>
os.chdir(new_directory) Note: For users of Colab, you will need to place a copy of the downloaded ‘Ch03’ folder onto your GDrive, remembering to mount your GDrive in your Colab notebook. Then you will be able to change your working directory using
import os
new_directory = <your file path to Ch03 ex: '/content/drive/My Drive/Ch03'>
os.chdir(new_directory) 3.3.3 Using References¶
from pxr import Usd, Sdf
def internal_reference(prim: Usd.Prim, ref_target_path: Sdf.Path):
references: Usd.References = prim.GetReferences()
references.AddInternalReference(
primPath=ref_target_path
)
def external_reference(prim: Usd.Prim, ref_asset_path: str):
references: Usd.References = prim.GetReferences()
references.AddReference(
assetPath=ref_asset_path
)create external reference to the example ‘Block_Blue.usd’
from pxr import Usd, UsdGeom, Sdf
stage = Usd.Stage.CreateNew("blocks.usda")
block1 = UsdGeom.Xform.Define(stage, "/World/Block1")
external_reference(
block1.GetPrim(),
<your file path to Block_Blue.usd ex:"./Assets/Block_Blue.usd">
)
stage.Save()3.3.4 Using Payloads¶
Create payload to the example ‘Block_Blue.usd’.
from pxr import Usd, Sdf, UsdGeom
def add_payload(prim: Usd.Prim, payload_asset_path: str):
payloads: Usd.Payloads = prim.GetPayloads()
payloads.AddPayload(
assetPath=payload_asset_path
)
stage = Usd.Stage.CreateNew("blocks_payload.usd")
block1 = UsdGeom.Xform.Define(stage, '/World/Block1')
add_payload(
block1.GetPrim(),
<your file path to Block_Blue.usd ex: "./Assets/Block_Blue.usd">
)
stage.Save()Unload
block1.GetPrim().Unload() Check if the data associated with the block1 prim is loaded. If the data is unloaded, the method will return False
block1.GetPrim().IsLoaded() Load back
block1.GetPrim().Load() 3.4 Setting Stage Properties¶
Set stage’s up-axis
from pxr import UsdGeom
UsdGeom.SetStageUpAxis(stage, UsdGeom.Tokens.y) Set the unit measurement
UsdGeom.SetStageMetersPerUnit(stage, 0.01) Set the default prim
stage.SetDefaultPrim(world_prim)
default_prim = stage.GetDefaultPrim()
stage.Save()3.5 Saving the Scene¶
Export blocks.usda stage to a different format
stage = Usd.Stage.Open("blocks.usda")
stage.Export("blocks.usdc") Export a .usd file as a .usdz
from pxr import UsdUtils
UsdUtils.CreateNewUsdzPackage("blocks.usda", "blocks.usdz")