Exercise: Assemblies#

In this exercise, we will create a new assembly asset called city_blockA that will reference lrg_bldgF multiple times to create a city block. We will set the model kind of the new asset to assembly.

  1. In Visual Studio Code, open the following file: asset_structure/exercise_10/create_assembly.py

  2. First, let’s set the model kind to assembly. Add the code below into the designated PART 1 section:

1Usd.ModelAPI(world_prim).SetKind(Kind.Tokens.assembly)

  1. Now we will populate the asset by referencing the component assets. Add the code below into the designated PART 2 section:

1for x in range(1,7):
2    ref_path: Sdf.Path = world_prim.GetPath().AppendChild(f"lrg_bldgF_{x:02}")
3    ref_target_prim = UsdGeom.Xform.Define(stage, ref_path).GetPrim()
4    ref_target_prim.GetReferences().AddReference("./lrg_bldgF/lrg_bldgF.usd")
5    position_bldg(ref_target_prim, x)

Assemblies aggregate assets made up of component assets or other assemblies. Here we are referencing lrg_bldgF six times and positioning them into a city block.

  1. Save the file and then execute the script using the following command:

Windows:

python .\asset_structure\exercise_10\create_assembly.py

Linux:

python ./asset_structure/exercise_10/create_assembly.py

  1. Run the following command in Visual Studio Code to open the file in usdview:

Windows:

.\scripts\usdview.bat .\asset_structure\exercise_10\city_blockA.usd

Linux:

./scripts/usdview.sh ./asset_structure/exercise_10/city_blockA.usd

  1. In usdview, click on the “World” (default) prim in the tree view. Note that the Meta Data tab shows that the kind field is set to assembly. This is an assembly asset.

  1. In usdview, click on “lrg_bldgF_01” prim in the tree view. Note that the Meta Data tab shows that the kind field is set to component. This is a component asset.

  1. Note that we have created a valid model hierarchy:

World (assembly)
    lrg_bldgF_01 (component)
    lrg_bldgF_02 (component)
    lrg_bldgF_03 (component)
    lrg_bldgF_04 (component)
    lrg_bldgF_05 (component)
    lrg_bldgF_06 (component)