---
name: img2threejs
description: Turn an object or character reference image into a quality-gated, animation-ready procedural Three.js model built in code. Use for image-to-3D reconstruction, detail-accurate object rebuilds, stylized/likeness-maximized human characters, sculpt specs, and staged code generation.
license: MIT
version: 1.2.0
---

# img2threejs — Image to procedural Three.js

Rebuild the object visible in a reference image as a **code-only** procedural Three.js model,
gated by a staged sculpting pipeline and an AI-vision self-correction loop. This is
reconstruction-by-code, **not** photogrammetry, mesh extraction, or downloaded art packs.

Agent-agnostic: works under Claude Code, Codex, or OpenCode. Wherever this doc says "agent
vision" or "agent browser tool", use whatever the host provides — native image reading, a
browser MCP (playwright/chrome-devtools), the project preview, or a user-supplied screenshot.

## When To Use

The user attaches/points to an object image and wants a procedural Three.js model, a
reconstruction/animation/destruction plan, a sculpt spec, or code. Also for material studies,
action-ready props, game objects, botanical/mechanical parts, and stylized reconstructions.

## Core Promise

Sculpt from a photo, in order — never one-shot a mesh:
1. **Validate** the image is a suitable 3D target (`grimoire/intake/validation_rubric.md`).
2. **Assess** object class + complexity, then write a `qualityContract` before any code.
3. **Spec** it: component hierarchy, materials, lighting, pivots, sockets, action anchors.
4. **Build pass-by-pass** from blockout → structure → form → material → lighting → interaction → optimization.
5. **Verify** each pass with a screenshot compared against the reference; fail a pass if an identity-defining feature is wrong even when the global score looks fine.

State explicitly when output is approximate/stylized/low-poly. A single image cannot reveal
hidden sides or guarantee exact geometry — say so instead of faking confidence.

## Required Inputs

- one image path / screenshot / URL / attached image (if missing or unreadable, ask)
- intended use: prop, game object, hero render, playable/destructible object, animation rig
  (default: real-time browser prop with interactive performance)

## The Loop (scripts do enforcement; agent vision does judgment)

Run scripts from the skill root (`forge/...`). Pure Python 3.10+ stdlib, no pip installs.
Full flags: `grimoire/scripts.md`. Never let a script *score* visuals — that is the agent's job.

1. Probe local images: `forge/stage1_intake/probe_image.py <image>` (metadata only, not a visual check).
2. **Pre-Spec Assessment Gate** — classify + score complexity + write the quality contract:
   `forge/stage2_spec/new_pre_spec_assessment.py "Name" --image <img> --complexity <simple|moderate|complex|ultra-complex> --out assessment.json`. Rules: `grimoire/intake/quality_contract.md`.
   Set `objectClass.primaryDomain` (`object` | `character` | `hybrid`) and fill the seeded
   `detailInventory` (its `targetMinDetails` scales with complexity).
2b. **Detail inventory** (do not skip for detailed subjects) — scan zones and enumerate every
   identity-defining small detail (gloss, bevel, fasteners, linework, contours, stains):
   `forge/stage1_intake/build_detail_inventory.py <image> --mode grid-3x3 --out-dir <dir> --out di.json`.
   Each detail MUST map to a `component.localFeatures` or `material.localOverrides` entry — never
   prose only. Taxonomy + 3D-term recipes: `grimoire/intake/detail_inventory.md`.
2c. **Character/hybrid subjects** — capture head-unit proportions + facial/body landmarks:
   `forge/stage1_intake/extract_landmarks.py <image> --out anatomy.json --overlay overlay.png`, then
   fill `preSpecAssessment.anatomy`. Route: `grimoire/character/reconstruction.md`. For maximum
   likeness use the projection-first path (`grimoire/character/likeness_maximization.md`): solve the camera
   (`stage1_intake/solve_camera_pose.py`), de-light the photo (`stage1_intake/delight_albedo.py`), and project it onto
   the fitted mesh (`stage3_build/bake_projected_texture.py`). A single image cannot guarantee 100% likeness —
   report per-region confidence and request more views for a real person.
3. Author the spec from the assessment:
   `forge/stage2_spec/new_sculpt_spec.py "Name" --image <img> --assessment assessment.json --out object-sculpt-spec.json`.
   Replace generic starter `featureReviewTargets` with the object's real identity-defining
   systems (≤5 critical, ≤3 important per pass); for characters add `anatomy-proportion`,
   `face-landmark-placement`, `pose-silhouette`, `outfit-and-palette`. Use 3D-graphics terms only
   (`grimoire/glossary/3d_vocabulary.md`), never "nice/smooth/shiny".
4. When material fidelity matters and a source image exists, extract reference PBR evidence per crop:
   `forge/stage1_intake/extract_pbr_evidence.py <crop> --out-dir <dir> --material-id <id> --target-threshold 0.7`.
   Confidence < 0.7 is a stop/refine-input signal, not a pass. It is inference, not inverse rendering.
5. Validate, then strict-validate before generating code:
   `forge/stage2_spec/validate_sculpt_spec.py object-sculpt-spec.json` then `--strict-quality`.
   Strict blocks shallow specs (a complex object with one root, no repetition systems, no
   local overrides, no micro groups is NOT implementation-ready even if JSON validates).
6. **Locked build passes** — only touch the currently unlocked pass:
   `forge/stage3_build/orchestrate_passes.py status object-sculpt-spec.json`
   `forge/stage3_build/orchestrate_passes.py check object-sculpt-spec.json --pass-id <pass>`
   `forge/stage3_build/generate_threejs_factory.py object-sculpt-spec.json --out src/createObjectModel.ts`
   (generator is pass-gated: a future `--pass-id` fails until prior passes are reviewed `continue`).
7. Render the current pass in a browser/preview, capture a screenshot at a review viewpoint.
8. Package one side-by-side sheet, then inspect it with agent vision:
   `forge/stage4_review/make_comparison_sheet.py --reference <img> --render <shot> --out cmp.png --json`.
9. Record the review (overall + per-layer + per-feature scores + decision):
   `forge/stage4_review/append_review.py object-sculpt-spec.json --pass-id <pass> --fidelity <0-1> --action <continue|refine-spec|refine-code|request-input|stop> --summary "..." --render-screenshot <shot> --comparison-image cmp.png --ai-vision-score <0-1> --layer-scores-json '{...}' --feature-reviews-json <f.json> --in-place`.
10. Sync pipeline state after manual review edits:
    `forge/stage3_build/orchestrate_passes.py sync object-sculpt-spec.json --in-place`.

## Gates (do not skip)

- **Suitability**: pass / conditional / reject before any planning. `grimoire/intake/validation_rubric.md`.
- **Pre-spec / strict-quality**: blocks code gen until the spec is deep enough for its contract.
- **Screenshot feedback**: `continue` is allowed only with a render + comparison sheet + global
  AI-vision score ≥ threshold (default 0.7) AND every critical feature ≥ its own threshold.
  Details + per-layer scorecard: `grimoire/feedback/render_capture.md`.
- **Action-ready**: build a runtime hierarchy (pivots, sockets, colliders, destruction groups),
  never an inert lump; expose `root.userData.sculptRuntime`. `grimoire/readiness/action_rigging.md`.
- **Attachment**: child appendages (branches/limbs/handles/tubes) need `attachment.parentSocket`,
  `localStart`, `localEnd`, `contactType`, `embedDepth`/`overlap`, `gapTolerance` — no mid-air parts.
  `grimoire/readiness/joint_attachment.md`.
- **Material/lighting**: `grimoire/feedback/shading_realism.md` — independent PBR channels
  (never alias albedo into roughness/normal/AO), macro/meso/micro frequency bands, real lights.
- **Detail inventory**: for `moderate`+ subjects strict-quality blocks code gen until the
  `detailInventory` reaches `targetMinDetails` and every detail maps to a real component/material
  entry (gloss needs low-roughness/clearcoat; fasteners need instancing/micro parts).
- **Character track**: when `primaryDomain` is `character`/`hybrid` (or `--character`), the spec
  author auto-builds a stylized humanoid template (head/neck/torso/arms + hair, glasses,
  headphones, face features), flattened to world space under a hidden root, with per-part
  character materials and character build passes (`proportion-lock`, `feature-placement`).
  strict-quality requires a filled `anatomy` block (head-units, proportions, face landmarks) and
  character feature targets. Suitability routing for humans: `grimoire/intake/validation_rubric.md`
  (stylized vs maximum-likeness). Stylized bust, not a face-copy; refine positions per reference.

## Self-Correction

After every pass, decide exactly one: `continue | refine-spec | refine-code | request-input | stop`.
`refine-spec` fixes a wrong/missing/shallow spec (re-validate, don't patch code around it);
`refine-code` fixes geometry/material/lighting that doesn't match a sound spec. Full root-cause
guide + fidelity scale: `grimoire/review/self_correction.md`.

## Implementation Rules (brief)

TypeScript + plain Three.js unless the project uses a wrapper. `Group` factory
`createObjectNameModel(spec, options)`, reconstruction data kept separate from renderer objects,
deterministic seeds for all procedural noise. Prefer primitives / `Shape` extrude / curve+tube /
instancing / displacement / generated canvas textures before any external art. Full geometry &
material recipes + hard-won failure patterns: `grimoire/build/geometry_patterns.md`.

## Output

- **Analysis-only**: suitability verdict + scores, object extraction, macro→micro hierarchy,
  geometry strategy, material/lighting recipe, animation/destruction feasibility, plan + risks.
- **Implementation**: the above briefly, then edit code; verify with typecheck/build + a screenshot.
- **Not feasible**: name the blocker, ask for more views / cleaner image / accepted stylization /
  a narrower target. "This cannot reach the requested fidelity from this image" is a valid result.