CADScope

A browser-based 3D Viewer for CAD Assemblies, built with Three.js. Converts STEP files to Draco-compressed GLB with per-part colors and displays them in an interactive viewer with a scene hierarchy and preset camera views.

Viewing

1. Place a GLB file (preferrably draco compressed) in models/ (the viewer loads the path set in index.html)
2. Serve the project root: python -m http.server 8000
3. Open http://localhost:8000/index.html

Controls

• Left-drag — Orbit
• Middle/right-drag — Pan
• Scroll — Zoom
• View buttons (top-right) — Preset angles + zoom
• Scene hierarchy (left sidebar) — Expand/collapse nodes, toggle visibility

Converting STEP to GLB

Prerequisites:

• Python 3 (for STEP color extraction; stdlib only)
• Blender 5.0+ at /Applications/Blender.app
• FreeCAD 1.0+ at /Applications/FreeCAD.app

./model_converter/convert.sh models/input.step models/output.glb

# Without Draco compression
./model_converter/convert.sh --no-draco models/input.step models/output.glb

Pipeline

STEP → extract colors (Python) → FreeCAD (geometry + hierarchy) → Blender (apply colors + Draco) → GLB

Per-part colors are parsed directly from the STEP text (ISO 10303-21) since FreeCAD's headless mode can't access them. Colors are passed to Blender via a JSON sidecar and applied as Principled BSDF materials. Color extraction is non-fatal — if it fails, the pipeline still produces a valid GLB without colors.

You can inspect a STEP file's materials standalone:

python3 model_converter/extract_step_colors.py input.step /tmp/colors.json

Converter scripts

File	Role
convert.sh	Orchestrates the three-stage pipeline
extract_step_colors.py	Parses STEP text for color-to-part mappings (Python 3, no dependencies)
step_to_glb.py	FreeCAD script: STEP import, tessellation, uncompressed GLB export
blender_export.py	Blender script: GLB import, name cleaning, color application, Draco export

Future Possibilities...

• Would be cool to be able to select an item in the hierarchy and have it highlighted in the render
• Color Visualizer: Change color of [main] and [accent] parts.
  • Save configs/combinations?