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Blender is now a mandatory stage in draupnir's pipeline (Prime, 2026-09-28), and draupnir asked for eight add-ons from extensions.blender.org: SurfacePsycho 0.10.4, CAD Sketcher 0.32.1, 3D-Print Toolbox 1.4.1, STEP Importer 1.2.1, Bool Tool 2.1.0, LoopTools 4.7.7, MeasureIt 1.8.4, 3MF Import/Export 2.7.7. - stacks/blender/extensions.lock pins each by version and archive sha256. - scripts/blender-extensions sync builds fv-ml1:/tank/blender-extensions/5.2/system with Blender's own install-file, pre-warms and byte-compiles it, checks a read-only enable, then swaps it in. It refuses while the GUI or a blender-run job holds the old directory. - conf/scripts/startup/fleet_extensions.py enables every package in the System repo: in a timer in the GUI (after the prefs load), and as --python ahead of the caller's args in blender-run --extensions (a failed enable exits 1 before the caller's script). - It also patches SurfacePsycho's sp_overwrite_segment_selection from eval() to literal_eval(): the eval walked past MCP safe mode (control: unpatched ran code, patched refuses). - blender-run: --extensions (bind mounts via --mount so a missing source fails instead of being created); USER/LOGNAME set, which CAD Sketcher's getpass needs. - compose.yaml mounts the repo read-only and the hook into the GUI container. NOT yet deployed. - scripts/blender-probes/extensions_acceptance.py: one operator run per add-on, safe-mode compliant. Headless 8/9 online and with --network none; CAD Sketcher sketching is GUI-only. A Python audit hook saw no network/process events (positive control fired).
72 lines
4.4 KiB
Markdown
72 lines
4.4 KiB
Markdown
# Blender: headless and agent-driven 3D on fv-ml1 GPU 3
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**Blender 5.2.2 LTS** (bundled Python 3.13), runs on **fv-ml1 GPU 3** (RTX PRO 6000 Blackwell,
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96 GB). Stack and full notes: `/home/lkraven/development/eshpfi-management/stacks/blender/README.md`.
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⚠ **GPU 3 is borrowed.** It is the fleet's reserve card for a full-size vLLM seat. Blender
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runs only while in use, and this access ends if a big seat moves onto the card.
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## Two ways in
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| You are… | Use | Shape |
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| a script or CLI caller (renders, conversions) | `scripts/blender-run` | one-shot `docker run --rm`: no desktop, gone when Blender exits |
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| an agent building scenes interactively | `scripts/blender-mcp` (MCP, per task) | a GUI Blender plus the mcp-for-blender add-on; `up` / `status` / `down` |
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Both scripts are in `/home/lkraven/development/eshpfi-management/scripts/` and run from nh3-dev,
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reaching fv-ml1 as `infra-ops@10.251.50.54` over ssh. **No HTTP API** and no openapi.json.
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## blender-run (headless)
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```sh
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scripts/blender-run --job /path/to/jobdir -- --python render.py -- out.png
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scripts/blender-run --extensions --job /path/to/jobdir -- --python model.py
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scripts/blender-run -- --python-expr 'import bpy; print(bpy.app.version_string)'
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```
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- Always adds `-b --factory-startup --python-exit-code 1`. Arguments go after `--`.
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- **Files:** fv-ml1 does not mount `/mnt/smithy`. `--job DIR` mirrors DIR to
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`fv-ml1:/tank/blender/jobs/<basename>-<hash of DIR's absolute path>/`, runs with that as
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the working directory, and copies new or changed files back into DIR. Nothing is ever
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deleted locally, and a rerun starts from an exact mirror, never from leftovers. Use
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relative input paths inside the job. Do not run the same DIR twice at once.
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- **Engines headless (tested 2026-09-28):** Cycles on GPU (OptiX/CUDA), Cycles on CPU, EEVEE
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(EGL, no display needed, ~9 s with the shader compile on first use), Workbench. In 5.2 the
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EEVEE id is `BLENDER_EEVEE` (`BLENDER_EEVEE_NEXT` is gone). For Cycles GPU, set
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`prefs.compute_device_type = 'OPTIX'` and enable the OPTIX devices, then
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`scene.cycles.device = 'GPU'`. Factory startup defaults to CPU.
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- **Import:** STL is built in (`bpy.ops.wm.stl_import`). STEP, 3MF and the other add-ons need
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`--extensions` (below).
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- **`--extensions`** enables the pinned add-on set: SurfacePsycho 0.10.4 (NURBS patches, STEP/IGES
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export via its bundled OCP), CAD Sketcher 0.32.1, 3D-Print Toolbox 1.4.1, STEP Importer 1.2.1,
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Bool Tool 2.1.0, LoopTools 4.7.7, MeasureIt 1.8.4, 3MF Import/Export 2.7.7. Pins:
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`stacks/blender/extensions.lock`. If any add-on fails to enable, the run exits 1 before your
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script starts. It adds a few seconds of startup (the add-on wheels unpack per run), so it is
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off by default. **CAD Sketcher's sketch operators need the GUI** (they activate a workspace
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tool); headless they fail with "'NoneType' object has no attribute 'widget'". Operators that
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want a 3D View (MeasureIt, LoopTools) take a `bpy.context.temp_override(area=...)` with a
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screen datablock's VIEW_3D area. Worked calls for every add-on:
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`scripts/blender-probes/extensions_acceptance.py`. Full notes and foot-guns: the stack README,
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section "Extensions".
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- **Budget:** each run is capped at 64 GB RAM and 48 CPUs, with up to the whole 96 GB of VRAM.
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Keep to about 2 concurrent renders. It is not on irv-ml1, so irv-ml1's working-set budget
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does not apply.
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⚠ **Foot-guns** (all measured):
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- A `--python` script that raises exits **0** unless `--python-exit-code` is set. blender-run
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sets it.
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- `render.filepath` must be **absolute**. Blender does not resolve a relative output path
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against the working directory ("cannot save 'out.png'"). Importers and Python file I/O do.
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- Harmless stderr noise: "HIPEW initialization failed" (the AMD backend probing), and "Failed to
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create secure directory (/defaults): Operation not permitted" (the image's runtime-dir setup
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running as a non-root user; reported by draupnir 2026-09-28).
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- The first OptiX render in a process includes about 1-2 s of kernel load.
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## blender-mcp (agents)
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Register it **per task**, never user- or project-wide (Prime, 2026-09-27):
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`claude mcp add blender -- /home/lkraven/development/eshpfi-management/scripts/blender-mcp`.
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Then run `scripts/blender-mcp up`, wait for `status` to say answering, work, and run `down`
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when finished. Safe mode is on (no os/open/network in agent code), so the startup hook has
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already pointed Cycles at OptiX. Save to `/work/…`. Details and traps are in the stack README.
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