blender-pipeline

name	blender-pipeline
description	Use when the user wants to create or modify 3D assets for a BRICKS app using Blender — product models, mascots, environments, 3D logos, exhibition pieces — or to convert existing models (FBX/OBJ/USD/.blend) into BRICKS-ready glTF. Drives the local Blender install headlessly (blender -b -P script.py) with bundled script templates for procedural scenes, format conversion, model inspection, optimization, and preview renders; optionally uses the Blender MCP server for live iterative modeling. Encodes BRICKS-safe export settings - .glb with embedded textures, NO Draco/KTX2/meshopt compression (the Scene3D loader does not support them), applied transforms, sane scale, and per-device polygon/texture budgets. Triggers on "make a 3D model", "create it in Blender", "convert this FBX", "optimize this model for devices". Requires Blender installed on this machine. Do NOT use for composing the in-app scene, lighting, or camera (use scene3d-authoring) or for scene behavior (use scene3d-interactions).
license	MIT
metadata	{"version":"0.1.0","author":"BRICKS"}

Blender Pipeline

Create, convert, inspect, and optimize 3D assets with the user's local Blender, producing BRICKS-safe .glb files for the Scene3D brick.

Announce at start: "I'm using the blender-pipeline skill to prepare the 3D asset."

Step 0: Locate Blender

Find the binary once and reuse the path (single commands only — no pipes or chaining):

• macOS: /Applications/Blender.app/Contents/MacOS/Blender
• Linux: blender on PATH (or a ~/blender-*/blender unpack)
• Windows: C:\Program Files\Blender Foundation\Blender <ver>\blender.exe

Verify with <blender> --version — the bundled scripts support Blender 3.6+. If Blender is missing, stop and tell the user to install it (blender.org); don't attempt package managers unprompted.

Bundled scripts

Resolve paths against this skill directory. All run headless: <blender> -b -P <script.py> -- <args>. Each prints a ===JSON=== line followed by a machine-readable result.

Script	Purpose	Typical call
scripts/blender/inspect_model.py	Stats before deciding anything: objects, triangles, materials, texture sizes, animation clips, node names, dimensions	-- --in model.fbx
scripts/blender/import_export_glb.py	Convert any supported format to BRICKS-safe GLB; optional transform apply + size normalize	-- --in model.fbx --out out/model.glb --apply-transforms --max-dim 2
scripts/blender/new_scene.py	Build a procedural scene (primitives + text + PBR materials) from a JSON spec	-- --spec spec.json --out out/scene.glb
scripts/blender/optimize_model.py	Decimate meshes, downscale textures, optionally join meshes; reports before/after	-- --in in.glb --out out/opt.glb --ratio 0.5 --max-texture 2048
scripts/blender/preview_render.py	Quick turntable-style still for the user to approve before uploading	-- --in out/model.glb --out out/preview.png --size 800

Workflow

1. Inspect first (inspect_model.py) whenever a file exists — decisions about optimization, node overrides, and animations all come from its output. Surface the JSON summary to the user (tris, textures, clips).
2. Create or convert:
   • New asset from description → write a spec JSON (documented at the top of new_scene.py) → new_scene.py. Keep it simple — primitives + good PBR materials + text go a long way for signage.
   • Existing asset → import_export_glb.py with --apply-transforms and, for product-viewer use, --max-dim 2 (the Scene3D default camera sits at (3,3,5) looking at the origin, so a ~1–2 unit model frames well).
3. Check the budget (see references/export-checklist.md for the full checklist and per-device budgets). Over budget → optimize_model.py.
4. Preview (preview_render.py) and show the image to the user before uploading — a 10-second render saves a wrong-model round trip.
5. Hand off to scene3d-authoring: upload the .glb, wire it into the Scene3D brick. Pass along the inspect output — its nodes and animations lists are exactly what node overrides and playAnimation need.

Export rules (already enforced by the scripts)

• .glb (single binary), textures embedded.
• No Draco / KTX2 / meshopt — the Scene3D loader cannot read them.
• Transforms applied; +Y up (exporter default); real-world-ish scale.
• Keep material count low; PBR metallic/roughness is what Scene3D renders.

Live Blender MCP (optional)

If the plugin's blender MCP server is approved and running (Blender open, BlenderMCP addon's socket server started), prefer it for iterative work — "move the logo up a bit", material tweaks with visual feedback — then still finish with the headless export script for a compliant .glb. When the MCP server isn't available, everything above works without it; don't block on it.

When Not To Use

• Composing the in-app scene (objects/lights/camera/effects) — scene3d-authoring.
• Scene behavior, input, animations at runtime — scene3d-interactions.
• 2D assets (icons, images) — the built-in imagegen skill or normal design flow.
• The user has no Blender and just needs a simple shape — Scene3D primitives (box/sphere/text…) need no asset at all; skip Blender entirely.