MJCF Importer Extension [omni.importer.mjcf]

MJCF Import Commands

The following commands can be used to simplify the import process. Below is a sample demonstrating how to import the Ant MJCF included with this extension

import omni.kit.commands
from pxr import UsdLux, Sdf, Gf, UsdPhysics, PhysicsSchemaTools

# setting up import configuration:
status, import_config = omni.kit.commands.execute("MJCFCreateImportConfig")
import_config.set_fix_base(True)
import_config.set_import_inertia_tensor(True)

# Get path to extension data:
ext_manager = omni.kit.app.get_app().get_extension_manager()
ext_id = ext_manager.get_enabled_extension_id("omni.importer.mjcf")
extension_path = ext_manager.get_extension_path(ext_id)

# import MJCF
omni.kit.commands.execute(
    "MJCFCreateAsset",
    mjcf_path=extension_path + "/data/mjcf/nv_ant.xml",
    import_config=import_config,
    prim_path="/ant"
)

# get stage handle
stage = omni.usd.get_context().get_stage()

# enable physics
scene = UsdPhysics.Scene.Define(stage, Sdf.Path("/physicsScene"))
# set gravity
scene.CreateGravityDirectionAttr().Set(Gf.Vec3f(0.0, 0.0, -1.0))
scene.CreateGravityMagnitudeAttr().Set(9.81)

# add lighting
distantLight = UsdLux.DistantLight.Define(stage, Sdf.Path("/DistantLight"))
distantLight.CreateIntensityAttr(500)

class omni.importer.mjcf.scripts.commands.MJCFCreateImportConfig(*args: Any, **kwargs: Any)

Returns an ImportConfig object that can be used while parsing and importing. Should be used with the MJCFCreateAsset command

Returns: Parsed MJCF stored in an internal structure.
Return type: omni.importer.mjcf._mjcf.ImportConfig

class omni.importer.mjcf.scripts.commands.MJCFCreateAsset(*args: Any, **kwargs: Any)

This command parses and imports a given mjcf file.

Parameters

arg0 (str) – The absolute path the mjcf file
arg1 (omni.importer.mjcf._mjcf.ImportConfig) – Import configuration
arg2 (str) – Path to the robot on the USD stage
arg3 (str) – destination path for robot usd. Default is “” which will load the robot in-memory on the open stage.

This extension provides an interface to the MJCF importer.

Example

Setup the configuration parameters before importing. Files must be parsed before imported.

from omni.importer.mjcf import _mjcf
mjcf_interface = _mjcf.acquire_mjcf_interface()

# setup config params
import_config = _mjcf.ImportConfig()
import_config.fix_base = True

# parse and import file
mjcf_interface.create_asset_mjcf(mjcf_path, prim_path, import_config)

Refer to the sample documentation for more examples and usage

class omni.importer.mjcf._mjcf.Mjcf

create_asset_mjcf(self: omni.importer.mjcf._mjcf.Mjcf, fileName: str, primName: str, config: omni.importer.mjcf._mjcf.ImportConfig, stage_identifier: str = '') → None

Parse and import MJCF file.

Parameters

arg0 (str) – The absolute path to the mjcf
arg1 (str) – Path to the robot on the USD stage
arg2 (omni.importer.mjcf._mjcf.ImportConfig) – Import configuration
arg3 (str) – optional: path to stage to use for importing. leaving it empty will import on open stage. If the open stage is a new stage, textures will not load.

class omni.importer.mjcf._mjcf.ImportConfig

property convex_decomp: Decompose a convex mesh into smaller pieces for a closer fit

property create_body_for_fixed_joint: creates body for fixed joint

property create_physics_scene: add a physics scene to the stage on import

property default_drive_strength: default drive stiffness used for joints

property density: default density used for links

property distance_scale: Set the unit scaling factor, 1.0 means meters, 100.0 means cm

property fix_base: Create fix joint for base link

property import_inertia_tensor: Import inertia tensor from mjcf, if not specified in mjcf it will import as identity

property instanceable_usd_path: USD file to store instanceable mehses in

property make_default_prim: set imported robot as default prim

property make_instanceable: Creates an instanceable version of the asset. All meshes will be placed in a separate USD file

property merge_fixed_joints: Consolidating links that are connected by fixed joints

property override_com: whether to compute the center of mass from geometry and override values given in the original asset

property override_inertia_tensor: Whether to compute the inertia tensor from geometry and override values given in the original asset

property self_collision: Self collisions between links in the articulation

set_convex_decomp(self: omni.importer.mjcf._mjcf.ImportConfig, arg0: bool) → None

set_create_body_for_fixed_joint(self: omni.importer.mjcf._mjcf.ImportConfig, arg0: bool) → None

set_create_physics_scene(self: omni.importer.mjcf._mjcf.ImportConfig, arg0: bool) → None

set_default_drive_strength(self: omni.importer.mjcf._mjcf.ImportConfig, arg0: float) → None

set_density(self: omni.importer.mjcf._mjcf.ImportConfig, arg0: float) → None

set_distance_scale(self: omni.importer.mjcf._mjcf.ImportConfig, arg0: float) → None

set_fix_base(self: omni.importer.mjcf._mjcf.ImportConfig, arg0: bool) → None

set_import_inertia_tensor(self: omni.importer.mjcf._mjcf.ImportConfig, arg0: bool) → None

set_import_sites(self: omni.importer.mjcf._mjcf.ImportConfig, arg0: bool) → None

set_instanceable_usd_path(self: omni.importer.mjcf._mjcf.ImportConfig, arg0: str) → None

set_make_default_prim(self: omni.importer.mjcf._mjcf.ImportConfig, arg0: bool) → None

set_make_instanceable(self: omni.importer.mjcf._mjcf.ImportConfig, arg0: bool) → None

set_merge_fixed_joints(self: omni.importer.mjcf._mjcf.ImportConfig, arg0: bool) → None

set_override_com(self: omni.importer.mjcf._mjcf.ImportConfig, arg0: bool) → None

set_override_inertia(self: omni.importer.mjcf._mjcf.ImportConfig, arg0: bool) → None

set_self_collision(self: omni.importer.mjcf._mjcf.ImportConfig, arg0: bool) → None

set_visualize_collision_geoms(self: omni.importer.mjcf._mjcf.ImportConfig, arg0: bool) → None