Viser Viewer

The Viser viewer is an interactive browser-based visualization entry point for SAP Warp scenes. It loads the same YAML scene files used by benchmark.py, steps SolverSAP, and streams visual geometry through the official viser package.

Quick Run

Launch the default scene:

uv run python -m viewer.viser.sap_viewer --num-worlds 1

Launch a specific scene:

uv run python -m viewer.viser.sap_viewer --scene assets/yaml/multi_joints.yaml

The command prints a local URL such as http://localhost:8080. Open that URL in a browser to inspect the simulation.

Useful Runtime Flags

--scene

YAML scene file. Defaults to assets/yaml/unitree_g1_usd.yaml.

--duration and --frames

Stop after a simulated duration or exact frame count. Leave both unset for an interactive run.

--dt

Timestep override. Defaults to simulation.dt in the scene file.

--num-worlds

Number of replicated worlds. Defaults to simulation.num_worlds.

--viewer-fps

Target viewer display update rate. Higher values can look smoother but increase viewer overhead. The actual achieved viewer FPS depends on scene complexity, browser rendering cost, and recording overhead.

--substeps-per-frame

Number of simulation steps between viewer updates. Defaults to 1. Increasing this can improve simulation throughput at the cost of less frequent visual updates.

--disable-cuda-graph

Disable CUDA graph replay and step through the direct Python path.

MP4 Recording

Record the Viser browser output to an MP4 file:

uv run python -m viewer.viser.sap_viewer \
  --scene assets/yaml/multi_joints.yaml \
  --duration 5 \
  --record-mp4 outputs/multi_joints.mp4

Recording options:

--record-mp4

Output MP4 path.

--record-fps

Recording FPS. Defaults to --viewer-fps.

--record-width and --record-height

Browser capture size in pixels. Defaults to 1280x720.

--record-webgl

WebGL backend for the recording browser. The default gpu mode requests hardware WebGL. Use swiftshader only as a software fallback if headless GPU WebGL is unavailable on the machine.

Notes

The viewer uses visual meshes when the scene loader provides them. Primitive inline shapes can set a display color with a top-level color field:

shapes:
  - type: box
    hx: 0.1
    hy: 0.1
    hz: 0.75
    color: [0.1, 0.75, 1.0]

The viewer is not the benchmark path. For timing-only measurements, prefer benchmark.py.