gs.materials.FEM.Cloth#

gs.materials.FEM.Cloth simulates thin shells such as cloth and fabric using a shell-based FEM formulation in the IPC backend. Use it for garments, flags, and membranes where bending and stretching of a thin surface matter.

class genesis.engine.materials.FEM.cloth.Cloth(*, use_visual_raycasting: bool = False, E: float = 10000.0, nu: float = 0.49, rho: float = 200.0, hydroelastic_modulus: float = 10000000.0, friction_mu: float = 0.1, contact_resistance: float | None = None, hessian_invariant: bool = False, build: Any = None, pre_compute: Any = None, update_stress: Any = None, compute_energy_gradient_hessian: Any = None, compute_energy_gradient: Any = None, compute_energy: Any = None, mu: float = 0.0, lam: float = 0.0, idx: int | None = None, thickness: float = 0.001, bending_stiffness: float | None = None, model: Literal['linear', 'stable_neohookean', 'linear_corotated'] = 'stable_neohookean') → None[source]#

Cloth material for thin shell/membrane simulation using IPC.

This material is designed for cloth, fabric, and other thin flexible materials. It uses shell-based FEM formulation (NeoHookeanShell) in the IPC backend.

When used with FEMEntity, it signals to IPCCoupler that this entity should be treated as a 2D shell (cloth) rather than a 3D volumetric FEM object.

Parameters:

  • E (float, optional) – Young’s modulus (Pa), controlling stiffness. Default is 1e4 (10 kPa).

  • nu (float, optional) – Poisson’s ratio, describing volume change under stress. Default is 0.49 (nearly incompressible).

  • rho (float, optional) – Material density (kg/m³). Default is 200 (typical fabric).

  • thickness (float, optional) – Shell thickness (m). Default is 0.001 (1mm).

  • bending_stiffness (float, optional) – Bending resistance coefficient. If None, no bending resistance. Default is None.

  • model (str, optional) – FEM material model (not used for cloth, kept for compatibility). Default is “stable_neohookean”.

  • friction_mu (float, optional) – Friction coefficient. Default is 0.1.

  • contact_resistance (float | None, optional) – IPC contact resistance/stiffness override. None uses the IPC coupler global default. Default is None.

Notes

  • Only works with IPCCoupler enabled

  • Requires GPU backend

  • Only accepts surface mesh morphs (Mesh, etc.)

  • Uses FEMEntity infrastructure but simulated as 2D shell in IPC

Examples

>>> cloth = scene.add_entity(
...     morph=gs.morphs.Mesh(file="cloth.obj"),
...     material=gs.materials.FEM.Cloth(
...         E=10e3, nu=0.49, rho=200, thickness=0.001, bending_stiffness=10.0
...     ),
... )
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