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Concepts

Physics Backends

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Isaac Lab supports PhysX, Newton, and OvPhysX through shared asset, sensor, and scene APIs. Choose a backend for the runtime and solvers you need, then select a preset supported by your task. See Backends and Presets for launch commands.

Choose a backend

IsaacSim PhysX

PhysX simulation through Isaac Sim and Omniverse Kit, with TGS and PGS solvers.

Newton

Warp-native simulation without Isaac Sim. Choose from MJWarp, Kamino, VBD, and MPM solvers.

OvPhysX

PhysX simulation without Omniverse Kit, configured through USD. Install with the ovphysx extra.

Follow Installation for the supported installation paths and current optional extras. Do not combine OvPhysX with a Kit runtime in the same process.

For the general PhysX—Newton policy validation workflow, see /source/how-to/transfer_policies_between_physx_and_newton. When a checkpoint’s joint or body ordering differs from the target backend, use the articulation ordering guide.

IsaacSim PhysX

IsaacSim PhysX runs through Isaac Sim and Omniverse Kit. It uses the Temporal Gauss-Seidel (TGS) solver by default, with Projective Gauss-Seidel (PGS) also available. Configure scene settings through PhysxCfg and asset properties through schema_cfgs. Large or contact-rich scenes may need additional GPU buffer capacity.

See the IsaacSim PhysX guide for runtime details and Tune the PhysX Solver for solver and buffer settings.

Newton

Newton runs on Warp without requiring Isaac Sim. Its solvers cover different simulation needs: MJWarp and Kamino for rigid robots, VBD for cloth and soft bodies, and MPM for particle materials. Configure the backend with NewtonCfg and select a solver through solver_cfg. Native Warp arrays are available for custom simulation code.

See the Newton guide for solver choices, tuning guides, and native data access.

OvPhysX

OvPhysX runs PhysX without Isaac Sim or Omniverse Kit. It supports rigid objects, articulations, contact and motion sensors, and CUDA-based deformables, and can pair with OVRTX for rendering. Scene-level solver settings come primarily from USD’s PhysicsScene; OvPhysxCfg holds additional settings such as GPU buffer capacities. It cannot share a process with Kit.

See the OvPhysX guide for installation, supported features, and their configuration limits.

Find supported tasks and APIs

Backend support is task-specific. Use /source/isaaclab/environments to browse registered environments and presets, or ask a task for its current choices:

uv run isaaclab train --rl_library rsl_rl \
   --task Isaac-Cartpole-Direct --help

The help output is the source of truth for that task’s physics= choices. For native solver data and views, see the PhysX, Newton, and OvPhysX access guides. For field-level configuration, follow the generated API links for PhysxCfg, NewtonCfg, its solver configurations, and OvPhysxCfg.