isaaclab_newton.sim.spawners

Sub-module for Newton material configuration exports.

Classes

NewtonMaterialCfg	newton:* rigid-body material attributes read by Newton's USD material schema resolver.
NewtonDeformableBodyMaterialCfg	Newton-specific physics material parameters for volume deformable bodies.
NewtonDeformableMaterialCfg	Newton-specific material properties for a deformable body.
NewtonSurfaceDeformableBodyMaterialCfg	Newton-specific physics material parameters for surface deformable bodies.

Rigid Materials

class isaaclab_newton.sim.spawners.materials.NewtonMaterialCfg

Bases: RigidBodyMaterialFragment

newton:* rigid-body material attributes read by Newton’s USD material schema resolver.

Single-namespace fragment (see RigidBodyMaterialFragment) for the Newton-only friction knobs (torsional and rolling friction) and the per-material contact model (contact stiffness/damping, friction gain, adhesion) that replaces the deprecated per-shape ke/kd/kf/ka parameters. The NewtonMaterialAPI schema is applied (and the newton:* attributes authored) by the generic apply_namespaced() writer. None fields are left unchanged.

Note

The generated NewtonMaterialAPI USD schema currently only declares the two friction attributes; the four contact attributes are still authored as raw newton:* USD attributes and are read directly by Newton’s schema resolver.

Composes with other rigid-body material fragments (e.g. UsdPhysicsRigidBodyMaterialCfg) in the same fragment list passed to spawn_rigid_body_material_from_fragments(). For the legacy (non-fragment) equivalent, see NewtonMaterialPropertiesCfg.

Attributes:

torsional_friction	Torsional friction coefficient (resistance to spinning at a contact point) [dimensionless].
rolling_friction	Rolling friction coefficient (resistance to rolling motion) [dimensionless].
contact_stiffness	Contact normal-force stiffness [N/m].
contact_damping	Contact normal-force damping coefficient [N·s/m].
contact_friction_gain	Friction-force stiffness gain used by the tangential (friction) contact response [N·s/m].
contact_adhesion	shapes closer than this threshold experience an attractive (adhesive) force [m].

torsional_friction: float | None

Torsional friction coefficient (resistance to spinning at a contact point) [dimensionless].

Writes newton:torsionalFriction. Range: [0, inf).

rolling_friction: float | None

Rolling friction coefficient (resistance to rolling motion) [dimensionless].

Writes newton:rollingFriction. Range: [0, inf).

contact_stiffness: float | None

Contact normal-force stiffness [N/m].

Writes newton:contactStiffness. Replaces the deprecated per-shape ke contact parameter; used by the SemiImplicit, Featherstone, MuJoCo, and VBD solvers.

contact_damping: float | None

Contact normal-force damping coefficient [N·s/m].

Writes newton:contactDamping. Replaces the deprecated per-shape kd contact parameter; used by the SemiImplicit, Featherstone, MuJoCo, and VBD solvers.

contact_friction_gain: float | None

Friction-force stiffness gain used by the tangential (friction) contact response [N·s/m].

Writes newton:contactFrictionGain. Replaces the deprecated per-shape kf contact parameter; used by the SemiImplicit and Featherstone solvers.

contact_adhesion: float | None

shapes closer than this threshold experience an attractive (adhesive) force [m].

Writes newton:contactAdhesion. Replaces the deprecated per-shape ka contact parameter; used by the SemiImplicit and Featherstone solvers.

Type:

Contact adhesion distance

Deformable Materials

Newton provides the backend-specific deformable material cfgs. Deformable material spawning is unified in isaaclab.sim.spawners.materials.spawn_deformable_body_material().

class isaaclab_newton.sim.spawners.materials.NewtonDeformableBodyMaterialCfg

Bases: DeformableBodyMaterialBaseCfg, NewtonDeformableMaterialCfg

Newton-specific physics material parameters for volume deformable bodies.

Attributes:

k_mu	First Lame material parameter [Pa].
k_lambda	Second Lame material parameter [Pa].
k_damp	Damping stiffness for tetrahedral elements [Pa*s].
density	The material density [kg/m^3].
particle_radius	Particle radius [m] used by the Newton backend.

k_mu: float

First Lame material parameter [Pa]. Defaults to 1e5 Pa.

k_lambda: float

Second Lame material parameter [Pa]. Defaults to 1e5 Pa.

k_damp: float

Damping stiffness for tetrahedral elements [Pa*s]. Defaults to 0.0.

density: float

The material density [kg/m^3]. Defaults to 1.0 kg/m^3.

particle_radius: float

Particle radius [m] used by the Newton backend.

class isaaclab_newton.sim.spawners.materials.NewtonDeformableMaterialCfg

Bases: object

Newton-specific material properties for a deformable body.

These properties are set with the prefix newton:<property_name>.

Attributes:

density	The material density [kg/m^3].
particle_radius	Particle radius [m] used by the Newton backend.

density: float

The material density [kg/m^3]. Defaults to 1.0 kg/m^3.

particle_radius: float

Particle radius [m] used by the Newton backend.

class isaaclab_newton.sim.spawners.materials.NewtonSurfaceDeformableBodyMaterialCfg

Bases: SurfaceDeformableBodyMaterialBaseCfg, NewtonDeformableMaterialCfg

Newton-specific physics material parameters for surface deformable bodies.

Attributes:

tri_ke	Triangle area-preserving stiffness [Pa].
tri_ka	Triangle area stiffness [Pa].
tri_kd	Triangle area damping [Pa*s].
edge_ke	Bending stiffness [N*m].
density	The material density [kg/m^3].
particle_radius	Particle radius [m] used by the Newton backend.
edge_kd	Bending damping [N*m*s].

tri_ke: float

Triangle area-preserving stiffness [Pa]. Used by Newton backend for cloth meshes.

tri_ka: float

Triangle area stiffness [Pa]. Used by Newton backend for cloth meshes.

tri_kd: float

Triangle area damping [Pa*s]. Used by Newton backend for cloth meshes.

edge_ke: float

Bending stiffness [N*m]. Used by Newton backend for cloth meshes.

density: float

The material density [kg/m^3]. Defaults to 1.0 kg/m^3.

particle_radius: float

Particle radius [m] used by the Newton backend.

edge_kd: float

Bending damping [N*m*s]. Used by Newton backend for cloth meshes.

Newton MPM particle spawner utilities.

Classes

MPMParticleSpawnerCfg	Base configuration for declarative Newton MPM particle generation.
MPMGridCfg	Generate a regular MPM particle lattice in an axis-aligned local box.
MPMPointsCfg	Generate MPM particles from explicit local-space positions.
MPMParticleMaterialCfg	Per-particle material values consumed by Newton's implicit MPM solver.

MPM Particles

Declarative particle generation for MPMObject. The spawner creates a placeholder Xform prim; the particles themselves are emitted into the Newton model builder during replication.

class isaaclab_newton.sim.spawners.mpm.MPMParticleSpawnerCfg

Bases: SpawnerCfg

Base configuration for declarative Newton MPM particle generation.

Particle geometry is emitted directly into Newton during scene replication. The USD spawner creates only a lightweight placeholder prim used by Isaac Lab’s scene and cloning machinery.

Attributes:

material	Physical material values applied to generated particles.
visual_color	RGB display color for particle visualization.
visual_material	Optional visual-material spawner configuration bound to each particle cloud.
visible	Whether the spawned asset should be visible.
semantic_tags	List of semantic tags to add to the spawned asset.
copy_from_source	Whether to copy the asset from the source prim or inherit it.
spawn_path	Path where the prototype is spawned.
visual_update_frequency	USD-stage particle visualization update frequency in render frames.

material: MPMParticleMaterialCfg

Physical material values applied to generated particles.

visual_color: Sequence[float]

RGB display color for particle visualization.

visual_material: VisualMaterialCfg | None

Optional visual-material spawner configuration bound to each particle cloud.

visible: bool

Whether the spawned asset should be visible. Defaults to True.

semantic_tags: list[tuple[str, str]] | None

List of semantic tags to add to the spawned asset. Defaults to None, which means no semantic tags will be added.

The semantic tags follow the Replicator Semantic tagging system. Each tag is a tuple of the form (type, data), where type is the type of the tag and data is the semantic label associated with the tag. For example, to annotate a spawned asset in the class avocado, the semantic tag would be [("class", "avocado")].

You can specify multiple semantic tags by passing in a list of tags. For example, to annotate a spawned asset in the class avocado and the color green, the semantic tags would be [("class", "avocado"), ("color", "green")].

See also

For more information on the semantics filter, see the documentation for the semantics schema editor.

copy_from_source: bool

Whether to copy the asset from the source prim or inherit it. Defaults to True.

This parameter is only used when cloning prims. If False, then the asset will be inherited from the source prim, i.e. all USD changes to the source prim will be reflected in the cloned prims.

spawn_path: str | None

Path where the prototype is spawned. Defaults to None.

visual_update_frequency: int

USD-stage particle visualization update frequency in render frames.

class isaaclab_newton.sim.spawners.mpm.MPMGridCfg

Bases: MPMParticleSpawnerCfg

Generate a regular MPM particle lattice in an axis-aligned local box.

Attributes:

visible	Whether the spawned asset should be visible.
semantic_tags	List of semantic tags to add to the spawned asset.
copy_from_source	Whether to copy the asset from the source prim or inherit it.
spawn_path	Path where the prototype is spawned.
material	Physical material values applied to generated particles.
visual_color	RGB display color for particle visualization.
visual_material	Optional visual-material spawner configuration bound to each particle cloud.
visual_update_frequency	USD-stage particle visualization update frequency in render frames.
lower	Lower local-space corner [m], shape (3,).
upper	Upper local-space corner [m], shape (3,).
voxel_size	Target MPM voxel size [m], used with particles_per_cell to choose lattice resolution.
particles_per_cell	Particle resolution multiplier applied independently along each axis.
particle_placement	Particle placement convention.
jitter	Width of Newton's uniform per-axis jitter interval [m].
mass	Per-particle mass [kg].
radius	Particle radius [m].

visible: bool

Whether the spawned asset should be visible. Defaults to True.

semantic_tags: list[tuple[str, str]] | None

List of semantic tags to add to the spawned asset. Defaults to None, which means no semantic tags will be added.

The semantic tags follow the Replicator Semantic tagging system. Each tag is a tuple of the form (type, data), where type is the type of the tag and data is the semantic label associated with the tag. For example, to annotate a spawned asset in the class avocado, the semantic tag would be [("class", "avocado")].

You can specify multiple semantic tags by passing in a list of tags. For example, to annotate a spawned asset in the class avocado and the color green, the semantic tags would be [("class", "avocado"), ("color", "green")].

See also

For more information on the semantics filter, see the documentation for the semantics schema editor.

copy_from_source: bool

Whether to copy the asset from the source prim or inherit it. Defaults to True.

This parameter is only used when cloning prims. If False, then the asset will be inherited from the source prim, i.e. all USD changes to the source prim will be reflected in the cloned prims.

spawn_path: str | None

Path where the prototype is spawned. Defaults to None.

material: MPMParticleMaterialCfg

Physical material values applied to generated particles.

visual_color: Sequence[float]

RGB display color for particle visualization.

visual_material: VisualMaterialCfg | None

Optional visual-material spawner configuration bound to each particle cloud.

visual_update_frequency: int

USD-stage particle visualization update frequency in render frames.

lower: Sequence[float]

Lower local-space corner [m], shape (3,).

upper: Sequence[float]

Upper local-space corner [m], shape (3,).

voxel_size: float

Target MPM voxel size [m], used with particles_per_cell to choose lattice resolution.

particles_per_cell: float

Particle resolution multiplier applied independently along each axis.

For example, 2 doubles the lattice resolution along every axis and therefore creates approximately eight times as many particles in 3D.

particle_placement: Literal['boundary', 'cell_center']

Particle placement convention.

"boundary" preserves the original behavior by emitting particles on both box boundaries. "cell_center" emits one equal-volume particle at each lattice-cell center, so derived particle masses sum to the requested box mass.

jitter: float

Width of Newton’s uniform per-axis jitter interval [m].

Newton samples each position component in [-jitter / 2, jitter / 2].

mass: float | None

Per-particle mass [kg].

If None, mass is derived from the generated lattice-cell volume and material density.

radius: float | None

Particle radius [m].

If None, cell-centered placement uses the equal-volume radius whose represented cube volume matches the lattice-cell volume. Boundary placement uses half the largest lattice-cell size.

class isaaclab_newton.sim.spawners.mpm.MPMPointsCfg

Bases: MPMParticleSpawnerCfg

Generate MPM particles from explicit local-space positions.

Attributes:

visible	Whether the spawned asset should be visible.
semantic_tags	List of semantic tags to add to the spawned asset.
copy_from_source	Whether to copy the asset from the source prim or inherit it.
spawn_path	Path where the prototype is spawned.
material	Physical material values applied to generated particles.
visual_color	RGB display color for particle visualization.
visual_material	Optional visual-material spawner configuration bound to each particle cloud.
visual_update_frequency	USD-stage particle visualization update frequency in render frames.
positions	Local-space particle positions [m], shape (num_particles, 3).
velocities	Local-space particle velocities [m/s], shape (num_particles, 3).
mass	Positive particle masses [kg], either scalar or one value per particle.
radius	Positive particle radii [m], either scalar or one value per particle.

visible: bool

Whether the spawned asset should be visible. Defaults to True.

semantic_tags: list[tuple[str, str]] | None

List of semantic tags to add to the spawned asset. Defaults to None, which means no semantic tags will be added.

The semantic tags follow the Replicator Semantic tagging system. Each tag is a tuple of the form (type, data), where type is the type of the tag and data is the semantic label associated with the tag. For example, to annotate a spawned asset in the class avocado, the semantic tag would be [("class", "avocado")].

You can specify multiple semantic tags by passing in a list of tags. For example, to annotate a spawned asset in the class avocado and the color green, the semantic tags would be [("class", "avocado"), ("color", "green")].

See also

For more information on the semantics filter, see the documentation for the semantics schema editor.

copy_from_source: bool

Whether to copy the asset from the source prim or inherit it. Defaults to True.

This parameter is only used when cloning prims. If False, then the asset will be inherited from the source prim, i.e. all USD changes to the source prim will be reflected in the cloned prims.

spawn_path: str | None

Path where the prototype is spawned. Defaults to None.

material: MPMParticleMaterialCfg

Physical material values applied to generated particles.

visual_color: Sequence[float]

RGB display color for particle visualization.

visual_material: VisualMaterialCfg | None

Optional visual-material spawner configuration bound to each particle cloud.

visual_update_frequency: int

USD-stage particle visualization update frequency in render frames.

positions: Sequence[Sequence[float]]

Local-space particle positions [m], shape (num_particles, 3).

velocities: Sequence[Sequence[float]] | None

Local-space particle velocities [m/s], shape (num_particles, 3).

If None, all initial velocities are zero.

mass: float | Sequence[float]

Positive particle masses [kg], either scalar or one value per particle.

radius: float | Sequence[float]

Positive particle radii [m], either scalar or one value per particle.

class isaaclab_newton.sim.spawners.mpm.MPMParticleMaterialCfg

Bases: object

Per-particle material values consumed by Newton’s implicit MPM solver.

This lightweight value configuration does not create or bind a USD material. Its values are forwarded to Newton as mpm:* custom attributes when particles are emitted into the model builder. Density is used only when a particle generator derives mass.

The defaults model a dry sand-like granular material.

Attributes:

density	Particle material density [kg/m^3] used to derive particle mass.
young_modulus	Young's modulus [Pa].
poisson_ratio	Dimensionless Poisson's ratio for elasticity.
viscosity	Plastic viscosity [Pa·s].
friction	Dimensionless particle friction coefficient.
damping	Elastic damping relaxation time [s].
yield_pressure	Pressure at which the material yields [Pa].
tensile_yield_ratio	Dimensionless tensile-to-compressive yield ratio.
yield_stress	Von Mises yield stress [Pa].
hardening	Dimensionless plastic hardening factor.
dilatancy	Dimensionless granular dilatancy factor.

density: float

Particle material density [kg/m^3] used to derive particle mass.

young_modulus: float

Young’s modulus [Pa].

poisson_ratio: float

Dimensionless Poisson’s ratio for elasticity.

viscosity: float

Plastic viscosity [Pa·s].

friction: float

Dimensionless particle friction coefficient.

damping: float

Elastic damping relaxation time [s].

yield_pressure: float

Pressure at which the material yields [Pa].

tensile_yield_ratio: float

Dimensionless tensile-to-compressive yield ratio.

yield_stress: float

Von Mises yield stress [Pa].

hardening: float

Dimensionless plastic hardening factor.

dilatancy: float

Dimensionless granular dilatancy factor.