Task 11.3 standalone proof

Split-Flap Primitive

This route is intentionally isolated from provider sync, dashboard composition, and the account app. It proves the primitive contract only: one active atlas, one physical track, local track indices, sprite-sheet glyphs, and a fixed top-then-bottom animation sequence driven by SetSymbol(index).

Home

Background sheet

480 x 240 sheet

Three 160 x 240 frames: stable flap, motion flap, and explicit blank.

Character atlas

2560 x 1920 / 16 x 8

One atlas cell is 160 x 240, with printable ASCII ordering on a tintable character sheet.

Production cadence

80ms / 100ms

The caller never manages intermediate frames or timings, and the proof now uses the locked 1x flip speed.

Live primitive

One flap, one atlas, one track.

Track

Uppercase / Characters

Phase

stable

Current

Blank

Target

Blank

Symbol Color

White

Controls

Change target state only.

The proof now assumes one shared character atlas with explicit per-flap tracks and the locked production cadence. Stable halves use the base atlas sheet, quarter overlays use the motion atlas sheet, and tintable atlases take their color from the flap instead of the sheet.

Symbol color
Local symbol targets

Asset contract

Two sheet families

  • Flap sheet owns the body and quarter-flip transition art.
  • Character atlas owns glyph lookup in printable ASCII order and stays tintable.
  • Tracks define the physical flip sequence per flap and stay explicit.

Animation contract

Fixed phase order

  • flipTop: outgoing top overlay is visible while the stable top commits immediately.
  • flipBottom: incoming bottom overlay is visible before the stable bottom settles.
  • Multi-step moves repeat the same local track step sequence at the locked production cadence.

Next integration

Ready for card composition

  • Keep the atlas lookup and track-local index model unchanged.
  • Carry per-flap symbol color only on tintable atlases.
  • Carry this primitive into card composition only after the primitive stays convincing.

Proof route: https://deetsdash.com/proof/split-flap