ldr2svg

Convert architecture diagrams and LDraw brick scenes into clean, editable isometric SVG illustrations.

What it does

ldr2svg turns diagrams into isometric brick illustrations. Each node becomes a coloured 2×2 brick, clusters become raised platforms, and edges become arching arrows — all rendered as a single SVG you can edit in Inkscape, LibreOffice Draw, or drop straight into Google Slides.

Three input formats are supported:

Format	Command	Example
diagrams Python scripts	diagram2svg	uv run diagram2svg arch.py
Mermaid flowcharts (.mmd)	mermaid2svg	uv run mermaid2svg arch.mmd
LDraw / LeoCAD (.ldr) brick scenes	ldr2svg	uv run ldr2svg scene.ldr

Example transformation

Input — diagrams-library output		Output — isometric brick SVG
	→

Usage

diagrams-library script → SVG

uv run diagram2svg arch.py -o arch_bricks.svg

Mermaid flowchart → SVG

uv run mermaid2svg arch.mmd -o arch_bricks.svg

LDraw scene → SVG

uv run ldr2svg scene.ldr

Outputs scene.svg alongside the input file.

Requirements

System dependencies

Tool	Purpose	Install
OpenSCAD	Render brick piece images	sudo apt install openscad
Graphviz	Lay out diagrams-library and Mermaid graphs (dot)	sudo apt install graphviz
Xvfb	Virtual display for headless OpenSCAD	sudo apt install xvfb

On macOS: brew install openscad graphviz (Xvfb not needed).

Python

• Python 3.10+
• uv

Install

uv sync

Development

uv run pytest test/ -m "not slow"   # fast unit tests (no OpenSCAD needed)
uv run ruff check ldr2svg/ test/    # lint
uv run ty check ldr2svg/            # type check

Slow integration tests (require OpenSCAD; use xvfb-run on headless systems):

xvfb-run uv run pytest test/ -v

How to import your SVG into Google Slides

1. Load the SVG into a LibreOffice presentation (tested on LibreOffice 24.2.7.2)
2. Click the image → contextual menu → Break the SVG
3. Save as .pptx (Microsoft PowerPoint 2007+)
4. Upload the .pptx into Google Slides

Credits and licences

• ldr2svg/brick.scad — derived from Thingiverse thing:5699, © 2015 Christopher Finke, MIT licence.

• LDraw — part geometry and colour definitions follow the LDraw open standard for Brick CAD programs. LDraw™ is a trademark of the Estate of James Jessiman.