Jenga

Many contacts

Lift a loose block and add it to the top of the tower.

Play0.00 s

¼×½×1×2×

Loop

The steel preset (the default), recordedon an NVIDIA RTX PRO 6000 Blackwell.

Run it

cd examples
# the default preset (steel), then the others
uv run shelf play jenga
# change solver settings live
uv run shelf tune jenga

Source: examples/shelf/02_many_contacts/jenga/ · ported from steel-webgpu assets/scenes/jenga (hero_montage export) @ ad03e49

Presets

Preset	Solver	Status	Checked
steeldefault	steel	works	2026-11-10, newton f6fc82a8b, NVIDIA RTX PRO 6000 Blackwell Server Edition

Solvers with no row are untested on this example. The full settings are inpresets.toml.

Code

example.py

examples/shelf/02_many_contacts/jenga/example.py

# SPDX-FileCopyrightText: Copyright (c) 2026 Skild AI and the Steel contributors
# SPDX-License-Identifier: Apache-2.0
# Direct source: steel-webgpu; see presets.toml and THIRD_PARTY.md.
# Modified for Steel Shelf: preset-driven execution and shared runner integration.

###########################################################################
# Example Jenga
#
# The arm picks up a loose block and places it across the top of the tower, continuing the alternating pattern.
#
# Rebuilt from steel-webgpu's exported scene (assets/scenes/jenga: scene.json
# and scene.bin, copied next to this file); see common/exported_scene.py. The
# visual meshes draw when a steel-webgpu checkout sits next to the shelf.
#
# Command: python -m shelf run jenga
#
###########################################################################

import newton.examples
from common.exported_scene import ExportedSceneExample


class Example(ExportedSceneExample):
    file = __file__


if __name__ == "__main__":
    parser = Example.create_parser()
    viewer, args = newton.examples.init(parser)
    newton.examples.run(Example(viewer, args), args)

example.py on GitHub

presets.toml

examples/shelf/02_many_contacts/jenga/presets.toml

example = "jenga"
source = "steel-webgpu assets/scenes/jenga (hero_montage export) @ ad03e49"
default = "steel"

[check]
# Arguments `python -m shelf check` passes in test mode.
args = []

[gallery]
short = "Lift a loose block and add it to the top of the tower."
title = "Jenga"
frame = 420

[xpbd]
status = "untested"

[vbd]
status = "untested"

[mujoco]
status = "untested"

[featherstone]
status = "untested"

[semi_implicit]
status = "untested"

[feather_pgs]
status = "untested"

[steel]
status = "works"
# 2 substeps x 16 iterations, colored response: 3.8 ms a frame on an RTX PRO 6000 (the port's 4 x 8 with sleeping:
# 6.3 ms). The block lands on the tower 2.8-3.8 mm from the top layer's centre, square to it, and the tower shifts
# under 1.5 mm, as at 4 x 8 and within 1.9 mm of a 16 x 32 run; penetration 1.0 mm peak, 0.17 mm mean (4 x 8: 0.8 /
# 0.13). 2 x 8 and 4 x 4 let the tower creep 3-19 mm, 2 x 12 doubles the mean penetration, point friction
# (friction_anchor_beta = 0) slides it 26 mm, and the immediate response costs 2.5x here (500 rows in one world).
# Sleeping off: the tower never sleeps under the arm, so it only cost 8%. Joint limits for the fingers, built within
# 0.1 of a limit; no joint has a finite velocity limit, so those rows are off.
sim = { fps = 60, substeps = 2 }
solver = { solve_mode = "matrix_free", iterations = 16, articulated_contact_response = "propagation_colored", enable_joint_limits = true, joint_limit_activation_gap = 0.1, enable_joint_velocity_limits = false, enable_sleeping = false, free_body_constraint_max = 8192, articulation_constraint_max = 1024, propagation_constraint_max = 16384 }
checked = "2026-11-10, newton f6fc82a8b, NVIDIA RTX PRO 6000 Blackwell Server Edition"

[kamino]
status = "untested"

[implicit_mpm]
status = "untested"

[style3d]
status = "untested"

presets.toml on GitHub

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