a6-numeral-roller

name	A6-numeral-roller
description	motion-graphic scene archetype — slot-machine-style digit swap with partial visibility of adjacent digits (previous on top, next on bottom). distinct from count-up which is smooth interpolation. canonical to stopwatch / odometer / dial idiom. composes numeral-roller as the sole hero effect on a single huge digit.

A6 — numeral roller

Composes

• numeral-roller (the hero effect — sole element of the scene)
• Optional decorative tick-marks (static SVG overlay) implying a physical dial

Layout

canvas: 1080x1920 (or pack-specified)

numeral_zone:
  anchor: center
  origin: { x: canvas_w/2, y: canvas_h/2 }
  align: center
  font_size: ~70% of frame height       # numerals are HUGE
  font_family: from pack (display)

tick_marks:                              # optional
  position: top-anchored across canvas
  count: 12
  color: pack.ink (white on black, etc.)

Per-digit layout balancing is required: '12' and '5' have different visual widths, so the digit's x-position rebalances per-glyph to keep visual mass centered. This is NOT pure center-align.

Choreography

phase_per_digit:
  beat_duration_frames: 24                # ~0.8s per digit at 30fps
  digit_roller_window_frames: 4           # how long the digit takes to "wipe" in
  hold_after_wipe_frames: 20              # static digit before next wipe

mechanical_easing: linear                 # the roller is mechanical, NOT springy

Each digit slides vertically through the frame slot-machine-style. The previous digit's bottom edge is briefly visible at the top, then the new digit is fully shown, then the next digit's top edge starts peeking at the bottom — implying a rotating drum.

Style pack compatibility

supported: [SP-A]
preferred_in: [SP-A]
incompatible: [SP-C, SP-D, SP-F, SP-G]

This archetype is rare; only SP-A has the mechanical-mono feel that fits it. Custom packs might support it.

Pack-specific overrides

SP-A (marshmallow) — adapted for "stopwatch" mode

• Bg: black (#0F0F0F) or pack ink (override of normal pink/cream).
• Numeral: white, Inter Black at ~960px font size on 1080×1920.
• Tick-marks: small white triangles, 12 of them across the top of canvas.

Duration

duration_seconds: [scene depends on digit count]
per_digit_seconds: 0.8                    # 12 digits = 9.6s total

Quality Checks

• Per-digit layout balance: '1' is positioned differently than '8' so visual mass stays centered.
• Linear motion only — no spring, no bezier overshoot. The roller is mechanical.
• Partial-digit visibility at top + bottom during the wipe window (3-5 frames).
• Tick-marks are static — they don't reposition with the digit.

Failure Modes

• Roller feels too snappy. Easing is non-linear; switch to linear.
• Digit appears to teleport (no partial visibility). Wipe window too short; bump to 4-5 frames.
• Visual mass shifts as digits change. Per-digit layout balance missing. Compute glyph width per digit and shift x accordingly.