Decision Engine

decision-engine

Purpose

When a fork appears in a traversal or inside a skill, pick the option using the documented choice libraries — not taste, not "it depends" without a rule.

Scope

Part 5 trees 5.1–5.19 and the style-dependent edges (Part 3.8). Does not execute the chosen workflow; returns the choice plus consequences.

Activation Conditions

• User asks "which / should I / Cycles or EEVEE / sim or fake / IK or FK / toon or realistic"
• Orchestrator or any skill hits a documented fork
• Use decision-engine

Non-Activation Conditions

• The choice is already locked in shared state
• The question is how to build the chosen system (that belongs to the owning skill)
• No fork exists (pure procedure)

Instructions

1. Identify the tree (5.1–5.19).
2. Ask only the missing condition that the table needs.
3. Return: choice, why, what it reconfigures downstream, what it forbids.
4. Write the lock into shared state when the choice is production-binding (style, engine, fps, naming, rig type).

Procedures

5.1 Style & look (fires at D04)

Realistic → anatomy, SSS, Cycles. Cartoon/game/toon, fast → stylized, EEVEE. Anime → 2-tone Shader-to-RGB, bold palettes. Abstract → GN + sims + comp. Hybrid → match grounding (lighting/render) to the hero element. Rule: decide at D04; switching mid-production = redoing lookdev.

5.2 Render engine (D113)

Film realism / refraction / SSS / volumes / time available → Cycles. Realtime, stylized, tight deadline, long film → EEVEE. Game pipeline → EEVEE or export. Blockout/previs → Workbench. Hybrid iterate EEVEE, hero Cycles — keep materials PBR-pure so the swap is settings, not re-lookdev.

5.3 Modeling workflow

Realistic human/creature film → sculpt-first → retopo → bake. Stylized boxy/cute → box-model + subdiv. Hard-surface → box + bevels + booleans + modifiers. City/backgrounds → modular + procedural. Original creature → sculpt-first + spec sheet. Hero prop → hybrid box + sculpt detail + bake.

5.4 Rig type

Biped → FK/IK switch + FK/BBone spine + stretch option. Quadruped → 4× leg IK + spine BBone + neck + tail. 6+ legs → per-leg IK + gait driver. Snake/tentacle/tail → BBone or FK + stretch. Wings → feather-row hierarchy + IK wingtip + fold. Mechanical → constrained axis, pistons, no soft deform. Cartoon stretchy → Stretch-to + squash/stretch global. Realistic facial → shape-key + bone control rig. Stylized facial → bone-driven. Minimal prop → single bone/constraint. Do not over-rig.

5.5 Hair / fur / feathers

Hero film hair → curves + manual groom + dynamics. Stylized hair → curves + simple sim or driver sway. Mammal fur → GN fur or curves + noise. Feathers → GN instances + wing hierarchy. Background → low-density or alpha cards. Realtime → cards/planes or low strand counts.

5.6 / 5.18 Sim vs fake

Rule: fake first. Sim only when faking is harder or visibly worse. Hero cloak → sim. Distant flag → vertex sway driver. Ocean → Ocean modifier. Puddle → ripple shader. Hero splash → sim or splash assets. Stylized fire breath → emissive curve + particles + glow. Realistic fire → sim. Rain → particles + wetness, not fluid. Jiggle → drivers/bones or soft body.

5.7 DoF & motion blur

Stylized/cheap DoF → comp Defocus on Z. Hero close-up realism → render DoF. Fast action MB → render 2–8% shutter. Cheap MB → vector blur in comp. Heavy scene → comp both; render MB off.

5.8 Format & color

Final frames → EXR multilayer. Edit master → ProRes 422 HQ / DNxHR. Web → H.264/H.265 CRF 18–23. Color → AgX. Film emulation → ACES/LUTs in comp.

5.9 Project structure

See production-finishing and knowledge/system/05-decision-trees.md 5.9 tree.

5.10 When to stop

Animation reads, contacts clean, second-eyes approved → lock animation. Hero materials approved under final lighting → lock lookdev. Caches stable → lock sims. Test frames clean, budget met → lock render. Pacing works, grade done, QC passed → deliver. Locks are promises. Honor them.

5.11 Add-ons

Learn the system first, add the speed tool second. Document the manifest. Built-in > add-on where equal. License-check assets.

5.12 Facial rig method

Realistic hero + lip sync → shape-key library + control rig (Ch 19). Stylized → bone-driven. Creature → bones + few species keys. Mocap face → ARKit-named blendshapes. Background → 3–5 keys. Never over-build. Toon drawn expressions → shape keys + GP overlay.

5.13 Shading style

Physical → Principled + maps. Cel → Shader-to-RGB ramp + hull outline. Anime → 2–3 tone + anime eye + face-shadow + selective outline. Cartoon → bold 2-tone, thick hull. Painterly → UV-perturb noise + soft comp. Game → stylized PBR + ramp. Mixed → separate ramps, grade together.

5.14 Mocap vs hand-key

Realistic human body, fast → mocap + foot fixes. Stylized/exaggerated → hand-key. Creatures → hand-key from animal ref. Dialogue CU → hand-key face/eyes; mocap body if useful. Hybrid (industry standard) → mocap body + hand-key face/hands/eyes.

5.15 Offline vs real-time

Film realism → Cycles. Stylized film / long runtime → EEVEE. Game/web → export pipeline (Ch 25).

5.16 Base mesh source

Build vs Rigify/base mesh vs scan. Film hero often sculpt-from-base or scan+retopo. Stylized often box or base mesh.

5.17 Outline method

Four methods in Ch 18.4 — pick per need (inverted hull, line art modifier, freestyle, GP).

5.19 Rig build order

The checklist is the tree. Follow templates/rig-signoff.md and Ch 6/28 order: skeleton → orientations → deform bones → IK/FK → spine/hands/feet → constraints → controllers → weights → correctives → facial → sign-off.

Inputs

• Fork id or natural-language choice
• Project style, medium, budgets, whether hero vs background

Outputs

CHOICE
- tree: 5.x
- pick: ...
- because: ...
- lock?: yes/no
- reconfigures: [downstream domains/skills]
- forbids: ...

Tools

• knowledge/system/05-decision-trees.md (full tables)
• Shared state locks

Constraints

Do not invent a fifth engine or a sixth style path without using A.3 extension protocol. Do not override a lock without calling out a feedback loop.

Edge Cases

Conflicting signals ("realistic anime") → treat as hybrid; ask which element is hero. Mixed toon/PBR is legal (5.13 mixed).

Failure Modes & Fixes

Dependencies

None required. Consumes shared state. Produces locks that all skills must respect.

Related Skills

All skills consume this. Closest: bakg-orchestrator.

Delegation Rules

After choosing, hand back to the caller. If the caller was the user, name the skill that should execute next.

Examples

• "Cycles or EEVEE for a rainy city with crystal refraction?" → Cycles (refraction/SSS/volumes).
• "Should I sim the distant flags?" → No. Vertex sway driver.
• "Bone face or blendshapes for a talking realistic hero?" → Shape-key library + control rig (5.12).

Required Knowledge / Context

• knowledge/system/05-decision-trees.md
• knowledge/system/03-relationship-map.md (section 3.8 style-dependent edges)
• context/production-economy.md

References to Shared Resources

• orchestration/ultimate-test.md
• templates/idea-decomposition.md