Ae Transition Kit

AE Transition Kit — reusable seams (→ .mogrt library)

Premiere's native transition registry is unreliable on recent versions; the premium path is a house library of AE-authored transitions exported as .mogrt (placed in Premiere via pr_import_mogrt on the track above the seam). This skill is how those get BUILT.

The transition comp template (start every build here)

• One comp, duration 0.5-0.8s (12-20 frames at 25/30fps) — transitions are seasoning, not scenes.
• Two placeholders: solid OUT_PLATE (what's leaving) and solid IN_PLATE (what's arriving), full-frame, bottom of the stack. Build all motion ABOVE/ON them; in Premiere the plates are replaced by (or revealed over) the real clips.
• Resolution-agnostic by construction: every position/size as an expression off thisComp.width / thisComp.height (e.g. anchor at [thisComp.width/2, thisComp.height/2]), never a baked pixel number — one build must work at 1920×1080 AND 1080×1920 (our vertical focus).
• Boundary-frame invariant: frame 0 = 100% outgoing plate, last frame = 100% incoming plate — no half-state at either end, or the seam pops in Premiere. Verify with ae_export_frame at first/last frame + ae_audit_frame if a reference exists.

Exposed-controls discipline (what makes it a LIBRARY piece, not a one-off)

• Parametrize, don't re-bake: hero tweakables live as Expression Controls on ONE CTRL null — Slider for duration-scale/blur amount/direction, Color for accent tints. Layers reference the control via expressions; a style change = one value, zero re-building.
• Cap at a handful (≤5) with tasteful defaults — a wall of sliders is worse than none.
• These controls are exactly what gets dragged into Essential Graphics for .mogrt export — name them like a human ("Direction (deg)", "Accent"), they become the template's public UI.
• Give text params stable names across the whole library (one convention → pr_import_mogrt's returned textParams are predictable for the agent driving them).

Worked builds (all geometry from comp-relative expressions; cubic bezier ease per ae-animation-principles)

Door open

Two full-frame layers, each masked to its half of the frame (left/right), anchors at the OUTER edges, 3D on. Y-rotate each to ±90° across the comp — the frame "opens" revealing IN_PLATE behind. Ease: slow-out heavy (doors accelerate); add a subtle exposure dip at the midpoint.

Card / cube flip

OUT_PLATE and IN_PLATE as 3D layers parented to one rotating null at frame centre; IN_PLATE pre-rotated 180° (back-to-back). Null Y-rotates 0→180° — out face leaves, in face arrives. A ~10% scale dip at the mid-rotation sells perspective without a camera.

Page peel

Use AE's native CC Page Turn on OUT_PLATE (fold position keyframed corner→opposite corner); IN_PLATE below. Don't hand-build the curl from masks — the effect exists, spend the effort on the ease and the drop shadow under the curl.

When NOT to reach for this kit

• Most seams want a hard cut (see the Premiere seam grammar) — a 3D transition on every cut reads as a 2010 wedding video. One family per project (STYLE LOCK applies to motion too), used at chapter changes, not between every shot.
• A plain crossfade/dip need is cheaper served by the Premiere keyframe fallback family (premiere-editing-reference Recipe I) — no AE round-trip.