viser4d 0.2.0

A viser extension with out-of-the-box support for the time dimension

viser4d

viser4d is a small wrapper around viser that adds a time dimension. It records scene operations across timesteps and can seek or play them back.

Quickstart

pip install viser4d

import numpy as np
import viser4d

server = viser4d.Viser4dServer(num_steps=10)

point_cloud = None
for i in range(10):
    with server.at(i):
        points = np.random.uniform(-1.0, 1.0, size=(200, 3))
        if point_cloud is None:
            point_cloud = server.scene.add_point_cloud(
                "/points",
                points=points,
                colors=(255, 200, 0),
            )
        else:
            point_cloud.points = points

server.play(fps=10, loop=True)
server.sleep_forever()

Timestep callbacks

If you have your own visualization logic and just want to use viser4d's timeline infrastructure (playback controls, seeking, scrubbing), you can register a callback that fires whenever the timestep changes:

import viser4d

server = viser4d.Viser4dServer(num_steps=100)

def on_timestep(t: int) -> None:
    # Update your custom visualizations here
    update_video_frames(t)
    update_body_meshes(t)
    update_3d_keypoints(t)

server.on_timestep_change(on_timestep)
server.play(fps=30, loop=True)
server.sleep_forever()

Callbacks are invoked after viser4d applies its own recorded state, so you can mix both approaches - record some operations with at(t) and handle others via callbacks.

How it works

Context determines behavior. server.scene always returns the same ProxyScene object, but it behaves differently based on whether you're inside an at(t) context:

Inside at(t):                          Outside at(t):
─────────────                          ──────────────
scene.add_frame(...)                   scene.add_frame(...)
       │                                      │
       ▼                                      ▼
    records to Timeline                    forwards to live viser scene

• Inside at(t): Operations are recorded to a timeline, not executed.
• Outside at(t): Operations forward directly to viser's live scene.
• Playback: seek(t) or play() applies recorded state to the live scene.

See examples/ for more.

Quality checks

uvx ruff format .
uvx ruff check .
uvx ty check

Tests

uv run --group dev pytest -q