A composition is a timeline of scene objects for cuts and cutscenes.
This first step brings the model and the pure evaluation behind it.
The tab and placing it in a scene follow in the next steps.
- CompositionAsset holds objects, tracks, items and clips. Each item
owns exactly one object with overrides and container edits.
- The composition is a third object holder next to scene and
container. Delete cascade, undo, usages and references work with it.
- Duplicating gives the copy new object ids and moves the item ids
along with them.
- compositionAt() tells which items live at a frame. The top track is
drawn in front.
- A clip acts on the item of its own track that it overlaps. After its
end it holds the last value until the item ends. The animation's
play mode is ignored, a clip is one pass.
- Clip targets are found by template path, else by name path, like
the runtime's animation system.
- The root sprite of an item plays its video driven at offset plus
time. Children follow unless they are already driven by hand.
- fittedLength() gives the video or clip length minus the offset, or
3 s without media.
- fps (60) and loop live in their own properties file. Keeping them in
PropertySchema would close an import cycle.
- The type is listed under Visuals with its own icon. It is not
placeable yet.
Tests: the gate passed with 300 files and 4625 tests. That is 25 new
tests in tests/core/composition.test.ts and 2 icon checks that run
for every icon. Four counter-checks (track order, overlap rule, child
videos, ids on duplicate) each turned exactly their test red. e2e 04
passed with 67 checks and now counts 33 asset types.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
adminandClaude Opus 5.5
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