Animation

usdtweak supports USD's time-sampled data through the Timeline panel and time-aware property editors.

Timeline panel

Enable the Timeline from Windows > Timeline. The Timeline provides:

• Playhead -- A draggable indicator showing the current frame. Drag it to scrub through the animation.
• Play/Stop -- Start and stop animation playback. During playback, the frame advances in real time based on the stage's timeCodesPerSecond metadata.
• Frame range -- The timeline range is determined by the stage's startTimeCode and endTimeCode metadata. If these are not set, the timeline defaults to a single frame.

The current time code set in the Timeline is shared across all viewports and property editors.

Playback behavior

When playback is active:

• The viewport updates each frame to show animated geometry, transforms, and materials.
• Property editors display the interpolated values at the current time.
• When playback reaches the end time code, it loops back to the start.

Stopping playback snaps the current time to the nearest whole frame.

Editing time-sampled attributes

Time-sampled attributes (attributes with values that change over time) can be viewed and edited in several places:

Stage Property Editor

The Stage Property Editor shows property values at the current time code. For time-sampled attributes, the displayed value corresponds to the current frame in the Timeline.

Attribute Editor

The Attribute Editor panel (Windows > Attribute editor) provides a detailed view of time samples, displaying values across multiple frames in a spreadsheet-like format. This is useful for:

• Inspecting animation curves and keyframe values
• Adding or removing time samples
• Editing individual keyframe values

Layer Property Editor

The Layer Property Editor shows the raw time samples authored in the current layer, including the full list of time-value pairs.

Animation metadata

Key stage-level metadata that controls animation:

Metadata	Description
startTimeCode	The first frame of the stage's animation range.
endTimeCode	The last frame of the stage's animation range.
timeCodesPerSecond	The playback speed in time codes per second (e.g., 24 for film).
framesPerSecond	The intended display rate in frames per second.

These can be set through the stage's root layer metadata.