Read and process Action Graph from USD file

Omniverse General Discussion
1

Hi,

I am trying to write an extension which has to open an USD file, find an Action Graph in it and execute the graph.
I could read the .usda file this way:

stage: Usd.Stage = Usd.Stage.Open(filename)

‘fileName’ comes from the extension.toml as a property.

But when I try to get the Action Graph in it like this:

(graph, _, _, _) = og.Controller.edit("/World/ag1")

I get this error:
2023-10-03 08:05:01 [2,240,102ms] [Error] [omni.ui.python] OmniGraphError: Could not find orchestration graph for stage GraphPipelineStage.GRAPH_PIPELINE_STAGE_SIMULATION

So it seems for me somehow the stage should be bundled to OmniGraph or application context but I don’t know how to do it from python code.
I tried to get the given graph on an other way too (e.g.: path = Sdf.Path(“/World/ag1”) …), I have found some examples but none of them works, obviously OmniGraph can’t see the stage I have loaded from .usda file.

How should I make Omnigraph connected to the stage I read from an .usda file, to be able to use the graph for further actions?

2

Try using something like the code below. It could be the stage has not loaded so it cannot grab the graph:

import asyncio
import carb
import omni.usd
import omni.graph.core as og

path_to_usd_file = 'path'
graph_id = '/World/ActionGraph'

async def open_stage():
	result, error = await omni.usd.get_context().open_stage_async(path_to_usd_file, load_set=omni.usd.UsdContextInitialLoadSet.LOAD_NONE)
	stage = omni.usd.get_context().get_stage()
	controller = og.Controller()
	graph = controller.graph(graph_id)
	if graph:
		carb.log_info("graph exists")
run_loop = asyncio.get_event_loop()
run_loop.create_task(open_stage())