| name | render-ldraw |
| description | Render an LDraw model (.ldr or .mpd) or a bundle directory to PNG images from front, iso, and top views so it can be visually inspected. Use whenever asked to see, view, preview, screenshot, render, or visually check a generated model — or to confirm a placement, colour, or stability change looks right in the actual bricks rather than only in numbers. |
| license | GPL-3.0-or-later |
Render and visually inspect a model
Tests confirm geometry and physics, but they don't show what the model
looks like. This skill renders a model (or a bundle — the primary
model is found through its bundle.json) to PNGs and reads them back so
shape fidelity, colours, gaps, and floating bricks can be judged by eye.
Requirements
Needs legolization 0.6.0 or newer — check with legolization --version.
If it is missing or older, install the latest stable release with
uv tool install legolization@latest
(or pip install --upgrade legolization). Only if neither package
manager is available, fall back to the standalone installer:
curl -LsSf https://uvx.sh/legolization/install.sh | sh
(PowerShell: irm https://uvx.sh/legolization/install.ps1 | iex).
If installation fails, report the failure and stop.
Conversation contract
- Explain the likely outcome in plain language before running anything.
- Never install a renderer without asking;
--check costs nothing and
is always safe.
- Run the CLI with
--json; present the image paths, what the images
show, warnings, and the next useful action.
Workflow
-
Check for a renderer using this skill's script:
bash scripts/setup-renderer.sh --check
(Windows: scripts/setup-renderer.ps1 -Check.) It prints
renderer=NAME or renderer=NONE.
-
If NONE: explain the per-platform install — LDView via Homebrew on
macOS, LeoCAD via winget on Windows, LeoCAD plus Xvfb via apt on
Ubuntu — and ask for consent before running the script's install
mode (the same script with no flag). Report an install failure and
stop; never improvise a different renderer.
-
Render:
legolization model render MODEL --json
The input may be a .ldr/.mpd file or a bundle directory. Useful
flags: --views iso (single angle, faster; default is
front,iso,top), --size 1600 (wider images), -o DIR. Existing
images are never overwritten — new renders take numeric suffixes, and
prior renders are retained even when the renderer or parts library
changes, so a change can be diffed against the previous look.
-
Read every produced PNG with the Read tool and apply the checklist:
- silhouette matches the source shape (no missing limbs or regions)
- no unexpected holes or pits in surfaces
- colours match the input (no banding or stray colours)
- seam pattern: running-bond staggering, not tall aligned stacks
- no visibly detached or floating clusters
- staircase artifacts on slopes are expected; gross terracing is not
-
Describe what the images show against what was intended, then name
the next useful action (analysis for suspected instability,
compare-style sweeps for a wrong-looking placement).
Presenting results
The --json envelope (legolization.result/v1) lists each image under
artifacts with status, exit_code, warnings, and error on
failure. Judge success by the PNGs on disk, and read them — never
describe an image you have not opened.
| Exit | Status | Meaning |
|---|
| 0 | complete | every requested view rendered |
| 1 | error | no renderer, unreadable input, or invalid usage |
| 3 | partial | some requested views rendered, some failed — say which |
Advanced controls (only on request)
- The CLI honours a renderer-override environment variable (the package
name upper-cased, plus
_RENDERER; values ldview, leocad, or
none) when detection must be forced for one shell.
- The renderer and parts-library versions are recorded alongside the
renders for reproducibility.
