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rigid_dynamic_prim

RigidDynamicPrim

Bases: RigidPrim

Provides high level functions to deal with a dynamic rigid body prim and its attributes/properties. This class is used for rigid bodies that are not kinematic-only, meaning they are subject to physics simulation dynamics like gravity, forces, and collisions.

Parameters:

Name Type Description Default
relative_prim_path str

Scene-local prim path of the Prim to encapsulate or create.

 required
name str

Name for the object. Names need to be unique per scene.

 required
load_config None or dict

If specified, should contain keyword-mapped values that are relevant for loading this prim at runtime.

 None
Source code in OmniGibson/omnigibson/prims/rigid_dynamic_prim.py 
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class RigidDynamicPrim(RigidPrim):
    """
    Provides high level functions to deal with a dynamic rigid body prim and its attributes/properties.
    This class is used for rigid bodies that are not kinematic-only, meaning they are subject to physics simulation
    dynamics like gravity, forces, and collisions.

    Args:
        relative_prim_path (str): Scene-local prim path of the Prim to encapsulate or create.
        name (str): Name for the object. Names need to be unique per scene.
        load_config (None or dict): If specified, should contain keyword-mapped values that are relevant for
            loading this prim at runtime.
    """

    def __init__(
        self,
        relative_prim_path,
        name,
        load_config=None,
    ):
        # Set up rigid body view which will be filled in later
        self._rigid_prim_view = None

        # Run super init
        super().__init__(
            relative_prim_path=relative_prim_path,
            name=name,
            load_config=load_config,
        )

    def _post_load(self):
        # Make sure it's set to be a rigid body (not kinematic)
        if not self.is_attribute_valid("physics:kinematicEnabled"):
            self.create_attribute("physics:kinematicEnabled", False)
        if not self.is_attribute_valid("physics:rigidBodyEnabled"):
            self.create_attribute("physics:rigidBodyEnabled", True)
        self.set_attribute("physics:kinematicEnabled", False)
        self.set_attribute("physics:rigidBodyEnabled", True)

        # Create the rigid prim view
        # Import now to avoid too-eager load of Omni classes due to inheritance
        from omnigibson.utils.deprecated_utils import RigidPrimView

        # set reset_xform_properties to False for load time
        self._rigid_prim_view = RigidPrimView(self.prim_path, reset_xform_properties=False)

        # Run super method to handle common functionality
        super()._post_load()

    def update_handles(self):
        """
        Updates all internal handles for this prim, in case they change since initialization
        """
        # Validate that the view is valid if physics is running
        if og.sim.is_playing() and self.initialized:
            assert (
                self._rigid_prim_view.is_physics_handle_valid() and self._rigid_prim_view._physics_view.check()
            ), "Rigid prim view must be valid if physics is running!"

        assert not (
            og.sim.is_playing() and not self._rigid_prim_view.is_valid
        ), "Rigid prim view must be valid if physics is running!"

        self._rigid_prim_view.initialize(og.sim.physics_sim_view)

    def set_linear_velocity(self, velocity):
        """
        Sets the linear velocity of the prim in stage.

        Args:
            velocity (th.tensor): linear velocity to set the rigid prim to. Shape (3,).
        """
        self._rigid_prim_view.set_linear_velocities(velocity[None, :])

    def get_linear_velocity(self, clone=True):
        """
        Args:
            clone (bool): Whether to clone the internal buffer or not when grabbing data

        Returns:
            th.tensor: current linear velocity of the the rigid prim. Shape (3,).
        """
        return self._rigid_prim_view.get_linear_velocities(clone=clone)[0]

    def set_angular_velocity(self, velocity):
        """
        Sets the angular velocity of the prim in stage.

        Args:
            velocity (th.tensor): angular velocity to set the rigid prim to. Shape (3,).
        """
        self._rigid_prim_view.set_angular_velocities(velocity[None, :])

    def get_angular_velocity(self, clone=True):
        """
        Args:
            clone (bool): Whether to clone the internal buffer or not when grabbing data

        Returns:
            th.tensor: current angular velocity of the the rigid prim. Shape (3,).
        """
        return self._rigid_prim_view.get_angular_velocities(clone=clone)[0]

    def set_position_orientation(self, position=None, orientation=None, frame: Literal["world", "scene"] = "world"):
        """
        Set the position and orientation of the dynamic rigid body.

        Args:
            position (None or 3-array): The position to set the object to. If None, the position is not changed.
            orientation (None or 4-array): The orientation to set the object to. If None, the orientation is not changed.
            frame (Literal): The frame in which to set the position and orientation. Defaults to world.
                Scene frame sets position relative to the scene.
        """
        assert frame in ["world", "scene"], f"Invalid frame '{frame}'. Must be 'world' or 'scene'."

        # If no position or no orientation are given, get the current position and orientation of the object
        if position is None or orientation is None:
            current_position, current_orientation = self.get_position_orientation(frame=frame)
        position = current_position if position is None else position
        orientation = current_orientation if orientation is None else orientation

        # Convert to th.Tensor if necessary
        position = th.as_tensor(position, dtype=th.float32)
        orientation = th.as_tensor(orientation, dtype=th.float32)

        # Assert validity of the orientation
        assert math.isclose(
            th.norm(orientation).item(), 1, abs_tol=1e-3
        ), f"{self.prim_path} desired orientation {orientation} is not a unit quaternion."

        # Convert to from scene-relative to world if necessary
        if frame == "scene":
            assert self.scene is not None, "cannot set position and orientation relative to scene without a scene"
            position, orientation = self.scene.convert_scene_relative_pose_to_world(position, orientation)

        self._rigid_prim_view.set_world_poses(positions=position[None, :], orientations=orientation[None, [3, 0, 1, 2]])
        PoseAPI.invalidate()

    def get_position_orientation(self, frame: Literal["world", "scene"] = "world", clone=True):
        """
        Gets prim's pose with respect to the specified frame.

        Args:
            frame (Literal): frame to get the pose with respect to. Default to world.
                scene frame gets position relative to the scene.
            clone (bool): Whether to clone the internal buffer or not when grabbing data

        Returns:
            2-tuple:
                - th.Tensor: (x,y,z) position in the specified frame
                - th.Tensor: (x,y,z,w) quaternion orientation in the specified frame
        """
        assert frame in ["world", "scene"], f"Invalid frame '{frame}'. Must be 'world', or 'scene'."

        # Get the pose from the rigid prim view and convert to our format
        positions, orientations = self._rigid_prim_view.get_world_poses(clone=clone)
        position = positions[0]
        orientation = orientations[0][[1, 2, 3, 0]]  # Convert from (w,x,y,z) to (x,y,z,w)

        # Assert that the orientation is a unit quaternion
        assert math.isclose(
            th.norm(orientation).item(), 1, abs_tol=1e-3
        ), f"{self.prim_path} orientation {orientation} is not a unit quaternion."

        # If requested, compute the scene-local transform
        if frame == "scene":
            assert self.scene is not None, "Cannot get position and orientation relative to scene without a scene"
            position, orientation = self.scene.convert_world_pose_to_scene_relative(position, orientation)

        return position, orientation

    @property
    def center_of_mass(self):
        """
        Returns:
            th.Tensor: (x,y,z) position of link CoM in the link frame
        """
        positions, orientations = self._rigid_prim_view.get_coms(clone=True)
        position = positions[0][0]
        return position

    @center_of_mass.setter
    def center_of_mass(self, com):
        """
        Args:
            com (th.Tensor): (x,y,z) position of link CoM in the link frame
        """
        self._rigid_prim_view.set_coms(positions=com.reshape(1, 1, 3))

    @property
    def mass(self):
        """
        Returns:
            float: mass of the rigid body in kg.
        """
        mass = self._rigid_prim_view.get_masses()[0]

        # Fallback to analytical computation of volume * density
        if mass == 0:
            return self.volume * self.density

        return mass

    @mass.setter
    def mass(self, mass):
        """
        Args:
            mass (float): mass of the rigid body in kg.
        """
        self._rigid_prim_view.set_masses(th.tensor([mass]))

    @property
    def density(self):
        """
        Returns:
            float: density of the rigid body in kg / m^3.
        """
        mass = self._rigid_prim_view.get_masses()[0]
        # We first check if the mass is specified, since mass overrides density. If so, density = mass / volume.
        # Otherwise, we try to directly grab the raw usd density value, and if that value does not exist,
        # we return 1000 since that is the canonical density assigned by omniverse
        if mass != 0.0:
            density = mass / self.volume
        else:
            density = self._rigid_prim_view.get_densities()[0]
            if density == 0.0:
                density = 1000.0

        return density

    @density.setter
    def density(self, density):
        """
        Args:
            density (float): density of the rigid body in kg / m^3.
        """
        self._rigid_prim_view.set_densities(th.tensor([density]))

    @property
    def is_asleep(self):
        """
        Returns:
            bool: whether this rigid prim is asleep or not
        """
        return og.sim.psi.is_sleeping(og.sim.stage_id, lazy.pxr.PhysicsSchemaTools.sdfPathToInt(self.prim_path))

    def enable_gravity(self):
        """
        Enables gravity for this rigid body
        """
        self._rigid_prim_view.enable_gravities()

    def disable_gravity(self):
        """
        Disables gravity for this rigid body
        """
        self._rigid_prim_view.disable_gravities()

    def wake(self):
        """
        Enable physics for this rigid body
        """
        prim_id = lazy.pxr.PhysicsSchemaTools.sdfPathToInt(self.prim_path)
        og.sim.psi.wake_up(og.sim.stage_id, prim_id)

    def sleep(self):
        """
        Disable physics for this rigid body
        """
        prim_id = lazy.pxr.PhysicsSchemaTools.sdfPathToInt(self.prim_path)
        og.sim.psi.put_to_sleep(og.sim.stage_id, prim_id)

    @property
    def stabilization_threshold(self):
        """
        Returns:
            float: threshold for stabilizing this rigid body
        """
        return self.get_attribute("physxRigidBody:stabilizationThreshold")

    @stabilization_threshold.setter
    def stabilization_threshold(self, threshold):
        """
        Sets threshold for stabilizing this rigid body

        Args:
            threshold (float): stabilizing threshold
        """
        self.set_attribute("physxRigidBody:stabilizationThreshold", threshold)

    @property
    def sleep_threshold(self):
        """
        Returns:
            float: threshold for sleeping this rigid body
        """
        return self.get_attribute("physxRigidBody:sleepThreshold")

    @sleep_threshold.setter
    def sleep_threshold(self, threshold):
        """
        Sets threshold for sleeping this rigid body

        Args:
            threshold (float): Sleeping threshold
        """
        self.set_attribute("physxRigidBody:sleepThreshold", threshold)

    @property
    def solver_position_iteration_count(self):
        """
        Returns:
            int: How many position iterations to take per physics step by the physx solver
        """
        return self.get_attribute("physxRigidBody:solverPositionIterationCount")

    @solver_position_iteration_count.setter
    def solver_position_iteration_count(self, count):
        """
        Sets how many position iterations to take per physics step by the physx solver

        Args:
            count (int): How many position iterations to take per physics step by the physx solver
        """
        self.set_attribute("physxRigidBody:solverPositionIterationCount", count)

    @property
    def solver_velocity_iteration_count(self):
        """
        Returns:
            int: How many velocity iterations to take per physics step by the physx solver
        """
        return self.get_attribute("physxRigidBody:solverVelocityIterationCount")

    @solver_velocity_iteration_count.setter
    def solver_velocity_iteration_count(self, count):
        """
        Sets how many velocity iterations to take per physics step by the physx solver

        Args:
            count (int): How many velocity iterations to take per physics step by the physx solver
        """
        self.set_attribute("physxRigidBody:solverVelocityIterationCount", count)

    def _dump_state(self):
        # Grab pose from super class
        state = super()._dump_state()

        state["lin_vel"] = self.get_linear_velocity(clone=False)
        state["ang_vel"] = self.get_angular_velocity(clone=False)

        return state

    def _load_state(self, state):
        # If we are part of an articulation, there's nothing to do, the entityprim will take care
        # of setting everything for us.
        if self._belongs_to_articulation:
            return

        # Call super first
        super()._load_state(state=state)

        # Set velocities
        self.set_linear_velocity(
            state["lin_vel"] if isinstance(state["lin_vel"], th.Tensor) else th.tensor(state["lin_vel"])
        )
        self.set_angular_velocity(
            state["ang_vel"] if isinstance(state["ang_vel"], th.Tensor) else th.tensor(state["ang_vel"])
        )

    def serialize(self, state):
        # Run super first
        state_flat = super().serialize(state=state)

        return th.cat(
            [
                state_flat,
                state["lin_vel"],
                state["ang_vel"],
            ]
        )

    def deserialize(self, state):
        # Call supermethod first
        state_dic, idx = super().deserialize(state=state)
        # We deserialize deterministically by knowing the order of values -- lin_vel, ang_vel
        state_dic["lin_vel"] = state[idx : idx + 3]
        state_dic["ang_vel"] = state[idx + 3 : idx + 6]

        return state_dic, idx + 6

center_of_mass property writable

Returns:

Type Description
Tensor

(x,y,z) position of link CoM in the link frame

density property writable

Returns:

Type Description
float

density of the rigid body in kg / m^3.

is_asleep property

Returns:

Type Description
bool

whether this rigid prim is asleep or not

mass property writable

Returns:

Type Description
float

mass of the rigid body in kg.

sleep_threshold property writable

Returns:

Type Description
float

threshold for sleeping this rigid body

solver_position_iteration_count property writable

Returns:

Type Description
int

How many position iterations to take per physics step by the physx solver

solver_velocity_iteration_count property writable

Returns:

Type Description
int

How many velocity iterations to take per physics step by the physx solver

stabilization_threshold property writable

Returns:

Type Description
float

threshold for stabilizing this rigid body

disable_gravity()

Disables gravity for this rigid body

Source code in OmniGibson/omnigibson/prims/rigid_dynamic_prim.py 
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def disable_gravity(self):
    """
    Disables gravity for this rigid body
    """
    self._rigid_prim_view.disable_gravities()

enable_gravity()

Enables gravity for this rigid body

Source code in OmniGibson/omnigibson/prims/rigid_dynamic_prim.py 
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def enable_gravity(self):
    """
    Enables gravity for this rigid body
    """
    self._rigid_prim_view.enable_gravities()

get_angular_velocity(clone=True)

Parameters:

Name Type Description Default
clone bool

Whether to clone the internal buffer or not when grabbing data

 True

Returns:

Type Description
tensor

current angular velocity of the the rigid prim. Shape (3,).
Source code in OmniGibson/omnigibson/prims/rigid_dynamic_prim.py 
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def get_angular_velocity(self, clone=True):
    """
    Args:
        clone (bool): Whether to clone the internal buffer or not when grabbing data

    Returns:
        th.tensor: current angular velocity of the the rigid prim. Shape (3,).
    """
    return self._rigid_prim_view.get_angular_velocities(clone=clone)[0]

get_linear_velocity(clone=True)

Parameters:

Name Type Description Default
clone bool

Whether to clone the internal buffer or not when grabbing data

 True

Returns:

Type Description
tensor

current linear velocity of the the rigid prim. Shape (3,).
Source code in OmniGibson/omnigibson/prims/rigid_dynamic_prim.py 
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def get_linear_velocity(self, clone=True):
    """
    Args:
        clone (bool): Whether to clone the internal buffer or not when grabbing data

    Returns:
        th.tensor: current linear velocity of the the rigid prim. Shape (3,).
    """
    return self._rigid_prim_view.get_linear_velocities(clone=clone)[0]

get_position_orientation(frame='world', clone=True)

Gets prim's pose with respect to the specified frame.

Parameters:

Name Type Description Default
frame Literal

frame to get the pose with respect to. Default to world. scene frame gets position relative to the scene.

 'world'
clone bool

Whether to clone the internal buffer or not when grabbing data

 True

Returns:

Type Description
2 - tuple
  • th.Tensor: (x,y,z) position in the specified frame
  • th.Tensor: (x,y,z,w) quaternion orientation in the specified frame
Source code in OmniGibson/omnigibson/prims/rigid_dynamic_prim.py 
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def get_position_orientation(self, frame: Literal["world", "scene"] = "world", clone=True):
    """
    Gets prim's pose with respect to the specified frame.

    Args:
        frame (Literal): frame to get the pose with respect to. Default to world.
            scene frame gets position relative to the scene.
        clone (bool): Whether to clone the internal buffer or not when grabbing data

    Returns:
        2-tuple:
            - th.Tensor: (x,y,z) position in the specified frame
            - th.Tensor: (x,y,z,w) quaternion orientation in the specified frame
    """
    assert frame in ["world", "scene"], f"Invalid frame '{frame}'. Must be 'world', or 'scene'."

    # Get the pose from the rigid prim view and convert to our format
    positions, orientations = self._rigid_prim_view.get_world_poses(clone=clone)
    position = positions[0]
    orientation = orientations[0][[1, 2, 3, 0]]  # Convert from (w,x,y,z) to (x,y,z,w)

    # Assert that the orientation is a unit quaternion
    assert math.isclose(
        th.norm(orientation).item(), 1, abs_tol=1e-3
    ), f"{self.prim_path} orientation {orientation} is not a unit quaternion."

    # If requested, compute the scene-local transform
    if frame == "scene":
        assert self.scene is not None, "Cannot get position and orientation relative to scene without a scene"
        position, orientation = self.scene.convert_world_pose_to_scene_relative(position, orientation)

    return position, orientation

set_angular_velocity(velocity)

Sets the angular velocity of the prim in stage.

Parameters:

Name Type Description Default
velocity tensor

angular velocity to set the rigid prim to. Shape (3,).

 required
Source code in OmniGibson/omnigibson/prims/rigid_dynamic_prim.py 
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def set_angular_velocity(self, velocity):
    """
    Sets the angular velocity of the prim in stage.

    Args:
        velocity (th.tensor): angular velocity to set the rigid prim to. Shape (3,).
    """
    self._rigid_prim_view.set_angular_velocities(velocity[None, :])

set_linear_velocity(velocity)

Sets the linear velocity of the prim in stage.

Parameters:

Name Type Description Default
velocity tensor

linear velocity to set the rigid prim to. Shape (3,).

 required
Source code in OmniGibson/omnigibson/prims/rigid_dynamic_prim.py 
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def set_linear_velocity(self, velocity):
    """
    Sets the linear velocity of the prim in stage.

    Args:
        velocity (th.tensor): linear velocity to set the rigid prim to. Shape (3,).
    """
    self._rigid_prim_view.set_linear_velocities(velocity[None, :])

set_position_orientation(position=None, orientation=None, frame='world')

Set the position and orientation of the dynamic rigid body.

Parameters:

Name Type Description Default
position None or 3 - array

The position to set the object to. If None, the position is not changed.

 None
orientation None or 4 - array

The orientation to set the object to. If None, the orientation is not changed.

 None
frame Literal

The frame in which to set the position and orientation. Defaults to world. Scene frame sets position relative to the scene.

 'world'
Source code in OmniGibson/omnigibson/prims/rigid_dynamic_prim.py 
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def set_position_orientation(self, position=None, orientation=None, frame: Literal["world", "scene"] = "world"):
    """
    Set the position and orientation of the dynamic rigid body.

    Args:
        position (None or 3-array): The position to set the object to. If None, the position is not changed.
        orientation (None or 4-array): The orientation to set the object to. If None, the orientation is not changed.
        frame (Literal): The frame in which to set the position and orientation. Defaults to world.
            Scene frame sets position relative to the scene.
    """
    assert frame in ["world", "scene"], f"Invalid frame '{frame}'. Must be 'world' or 'scene'."

    # If no position or no orientation are given, get the current position and orientation of the object
    if position is None or orientation is None:
        current_position, current_orientation = self.get_position_orientation(frame=frame)
    position = current_position if position is None else position
    orientation = current_orientation if orientation is None else orientation

    # Convert to th.Tensor if necessary
    position = th.as_tensor(position, dtype=th.float32)
    orientation = th.as_tensor(orientation, dtype=th.float32)

    # Assert validity of the orientation
    assert math.isclose(
        th.norm(orientation).item(), 1, abs_tol=1e-3
    ), f"{self.prim_path} desired orientation {orientation} is not a unit quaternion."

    # Convert to from scene-relative to world if necessary
    if frame == "scene":
        assert self.scene is not None, "cannot set position and orientation relative to scene without a scene"
        position, orientation = self.scene.convert_scene_relative_pose_to_world(position, orientation)

    self._rigid_prim_view.set_world_poses(positions=position[None, :], orientations=orientation[None, [3, 0, 1, 2]])
    PoseAPI.invalidate()

sleep()

Disable physics for this rigid body

Source code in OmniGibson/omnigibson/prims/rigid_dynamic_prim.py 
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def sleep(self):
    """
    Disable physics for this rigid body
    """
    prim_id = lazy.pxr.PhysicsSchemaTools.sdfPathToInt(self.prim_path)
    og.sim.psi.put_to_sleep(og.sim.stage_id, prim_id)

update_handles()

Updates all internal handles for this prim, in case they change since initialization

Source code in OmniGibson/omnigibson/prims/rigid_dynamic_prim.py 
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def update_handles(self):
    """
    Updates all internal handles for this prim, in case they change since initialization
    """
    # Validate that the view is valid if physics is running
    if og.sim.is_playing() and self.initialized:
        assert (
            self._rigid_prim_view.is_physics_handle_valid() and self._rigid_prim_view._physics_view.check()
        ), "Rigid prim view must be valid if physics is running!"

    assert not (
        og.sim.is_playing() and not self._rigid_prim_view.is_valid
    ), "Rigid prim view must be valid if physics is running!"

    self._rigid_prim_view.initialize(og.sim.physics_sim_view)

wake()

Enable physics for this rigid body

Source code in OmniGibson/omnigibson/prims/rigid_dynamic_prim.py 
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def wake(self):
    """
    Enable physics for this rigid body
    """
    prim_id = lazy.pxr.PhysicsSchemaTools.sdfPathToInt(self.prim_path)
    og.sim.psi.wake_up(og.sim.stage_id, prim_id)