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Sequencer Property Tracks

property name, optional component id, value type, enum type name, and reflected/writable/animatable flags.

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This document records the TODOS.phase-72.72.15.1.4 cinematic sequencer property-track contract. Property tracks animate reflected properties through a stable PropertyPath, binding id, reflected property metadata, typed keyframes, and the existing interpolation system.

Runtime Ownership#

  • Runtime module: V2Cinematics
  • Property value enum: EV2SequencerPropertyValueType
  • Property issue enum: EV2SequencerPropertyTrackIssueType
  • Reflected property spec: FV2SequencerReflectedPropertySpec
  • Property evaluation: FV2SequencerPropertyTrackEvaluation
  • Property issue: FV2SequencerPropertyTrackIssue
  • Automation: V2.Cinematics.Sequencer.PropertyTracks
  • CI checker: V2/ue/Tools/check-v2-sequencer-property-tracks.py

Reflected Property Metadata#

FV2SequencerReflectedPropertySpec declares the property path, reflected property name, optional component id, value type, enum type name, and reflected/writable/animatable flags. A spec is valid only when it names a reflected property path and points to a writable animatable property. Enum property tracks must also declare EnumTypeName.

Supported Property Types#

The default property-track fixture covers the required reflected property families:

  • Transform: Track.Property.Cassia.Transform animates Transform.Location.
  • Color: Track.Property.Cassia.EmissiveTint animates Material.EmissiveTint.
  • Float: Track.Property.Cassia.Opacity animates Material.Opacity.
  • Bool: Track.Property.Cassia.Hidden animates Actor.bHiddenInGame.
  • Enum: Track.Property.Cassia.CombatStance animates Combat.Stance with EV2CombatStance values.

BuildSequencerPropertyKeyframe adds color and enum payloads to the existing keyframe model without changing older keyframe builders. Bool and enum tracks use step interpolation so discrete reflected properties do not drift between authored values.

Evaluation#

EvaluateSequencerPropertyTrack verifies that a track is a property-compatible track, resolves reflected property metadata, evaluates keyframe interpolation at the requested frame, checks that the resulting keyframe value type matches the reflected property type, and returns a typed FV2SequencerPropertyTrackEvaluation.

Validation issues cover non-property tracks, missing property paths, missing reflected metadata, empty tracks, interpolation failures, unsupported value types, missing enum type names, and missing enum values.

Verification#

Run:

bash
python3 V2/ue/Tools/check-v2-sequencer-property-tracks.py

Adjacent verification should include python3 V2/ue/Tools/check-v2-sequencer-keyframe-interpolation.py, python3 V2/ue/Tools/check-v2-sequencer-timeline-playback.py, python3 V2/ue/Tools/check-v2-sequencer-data-model.py, and python3 V2/ue/Tools/check-v2-cinematics-module.py.