Fighting Game · Guides & deep dives

Sequencer Thumbnail Preview

panel spec, and request.

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Task: TODOS.phase-72.72.15.2.12

The sequence thumbnail preview is a V2Editor TimelineVisualizer surface for auto-generating a PNG thumbnail from the first frame of a sequence and registering it for asset browser display.

Runtime API#

  • Panel spec: FV2SequencerThumbnailPreviewPanelSpec
  • Request: FV2SequencerThumbnailPreviewRequest
  • Thumbnail: FV2SequencerThumbnailPreviewSpec
  • Result: FV2SequencerThumbnailPreviewResult
  • Issue enum: EV2SequencerThumbnailPreviewIssueType

GenerateSequencerThumbnailPreview accepts the current sequence, thumbnail panel spec, and request. It validates first-frame generation, output path, dimensions, sequence duration, and camera-track availability before returning thumbnail metadata with a render target path, PNG output path, camera binding, size estimate, and asset-browser registration state.

Behavior#

  • The panel targets TimelineVisualizer and uses /V2Editor/RenderTargets/RT_SequencerThumbnailPreview.RT_SequencerThumbnailPreview.
  • Requests generate from frame 0 and write PNG output to the requested directory and file name stem.
  • Generated thumbnails preserve the selected sequence id, resolved camera binding id, thumbnail path, dimensions, render target, and first-frame time.
  • Results mark the thumbnail as generated, PNG written, and registered with the asset browser.
  • Validation rejects invalid panel settings, missing output paths, non-first frame requests, missing camera tracks, dimensions above panel limits, invalid frames, and invalid sequences.

QA Inventory#

  • Panel: verify render target, PNG output, first-frame generation, regeneration, camera preview, and asset browser registration support.
  • Generate: verify a default sequence produces Saved/SequencerThumbnails/CouncilIntro.png at 512x288 from frame 0.
  • Camera: verify the thumbnail resolves the first camera track binding.
  • Asset browser: verify generated state includes asset-browser-ready and PNG written flags.
  • Off-path: reject missing camera tracks, invalid frames, oversize thumbnails, missing output paths, and non-first-frame requests.

js_repl Playwright interaction was unavailable in this session and the affected surface is Unreal editor data rather than browser-rendered UI, so verification is through UE editor automation and contract gates.

Verification#

  • python3 V2/ue/Tools/check-v2-sequencer-thumbnail-preview.py
  • V2.Editor.Sequencer.ThumbnailPreview
  • python3 V2/ue/Tools/check-v2-editor-module.py
  • python3 V2/ue/Tools/check-v2-ci-workflow.py