blender

Blender 4.x 3D Creation Suite AI Skill Guide (Claude)

Overview & Engine Architecture

Blender 4.2 LTS / 4.3+ / 5.x is an open-source DCC suite. Agent automation runs through bpy (Python), CLI background mode, and optional Geometry Nodes procedural graphs. Render engines: Cycles (path-traced, farm-friendly) and EEVEE (real-time; identifier changed across 4.2→5.0 — resolve at runtime, do not hardcode BLENDER_EEVEE_NEXT).

Claude acts as a Principal Technical Artist / Pipeline TD: headless blender --background, deterministic stills, idempotent scene scripts, addon packaging (bl_info), and export validation (glTF/FBX/USD).

┌─────────────────────────────────────────────────────────────┐
│                 Blender automation stack                    │
│  bpy.data / RNA  →  depsgraph  →  Cycles|EEVEE  →  files  │
│  CLI: -b blend -P script.py  |  -E CYCLES -f N -a (last!)   │
│  Determinism: cycles.seed, fixed samples, no animated seed  │
└─────────────────────────────────────────────────────────────┘

Version pins (document in every pipeline README): pin Blender minor (e.g. 4.2.11 LTS). GPU backends: CUDA / OPTIX / HIP / ONEAPI / METAL after -- (see CLI render docs).

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When to use / when not to

Use when

• Batch stills/animations, asset conversion, procedural scene generation, CI smoke renders.
• Geometry Nodes or modifier stacks must be evaluated headlessly.
• You need reproducible Cycles output (golden frames, A/B materials).

Do not use when

• Real-time game runtime (use Unity/Godot/Unreal skills).
• Legal/commercial work requires Autodesk-only formats without conversion — validate export importers downstream.
• Host has no GPU and Cycles GPU is mandatory without CPU fallback plan.

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Operational Capabilities & Agent Directives

1. Data API first: Mutate bpy.data, scene, object properties; use bpy.ops only with explicit context overrides in --background.
2. CLI argument order: Put -o, -F, -E, frame range before -f/-a; render flags must be last or Blender ignores them.
3. Deterministic Cycles: Set scene.cycles.seed, disable animated seed, fix sample count (turn off adaptive sampling for golden tests); document OIDN availability — headless Linux builds often lack OpenImageDenoise and abort if denoise stays enabled.
4. Color management: Set scene.view_settings.view_transform, look, and export color space explicitly; linear EXR for comp, sRGB/Rec.709 for web stills — never assume default OCIO matches farm workers.
5. Engine resolution: scene.render.engine = bpy.context.preferences.addons['cycles'].preferences... or iterate bpy.types.RenderEngine — EEVEE enum names differ by version.
6. Exit codes: Wrap main(); on failure sys.exit(1) so CI fails; log blender --version at job start.