Getting started

Install

After the public release, ovnewton will be available from PyPI.

pip install ovnewton

Run the installed example

Run the installed example without rendering:

python -m ovnewton.examples.example_ovnewton_basic --device cpu --no-render

The example loads the scene_rigid_bodies.usda scene included in the ovnewton wheel. Install the examples extra to render it with ovrtx:

pip install "ovnewton[examples]"
python -m ovnewton.examples.example_ovnewton_basic

The simulation runs on cuda:0 by default. Pass --device cpu to simulate on the CPU. The wheel also includes a complete cartpole scene:

python -m ovnewton.examples.example_ovnewton_basic --stage scene_cartpole

Run a simulation

The scene_path below must point to a USD file supplied by your application.

import newton
import ovnewton
import ovstage
from ovstage import PopulationDomain, population

scene_path = "/path/to/scene.usd"

stage = ovstage.Stage()
population.open_usd(stage, scene_path, ordinal=1, domains=PopulationDomain.ALL)
stage.advance_write_floor(ordinal=1).wait()

binding = ovnewton.attach_ovstage(stage)
model = binding.model
solver = newton.solvers.SolverXPBD(model)
state_0 = model.state()
state_1 = model.state()
control = model.control()
contacts = model.contacts()

num_substeps = 4
dt = 1.0 / (60 * num_substeps)
ordinal = 2

for _ in range(240):
    for _ in range(num_substeps):
        state_0.clear_forces()
        model.collide(state_0, contacts)
        solver.step(state_0, state_1, control, contacts, dt)
        state_0, state_1 = state_1, state_0

    binding.update_to_ovstage(state_0, ordinal=ordinal)
    stage.advance_write_floor(ordinal).wait()
    ordinal += 1

Call binding.update_from_ovstage(state_0, control) before a step to apply all supported state and drive target fields from sealed stage changes. This updates both state_0 and control; callers cannot select a subset. If you supply model=, its body and joint labels must match the stage paths.