Systems Architecture

vflow2 has four major systems beyond basic IFC analysis tools:

1. Connection Graph

Files: tools/_connection_graph.py + tools/connection_graph.py

• Assigns connection points (nodes) to all IFC elements (walls, doors, slabs, spaces)
• Creates edges between physically touching points using KDTree proximity (0.05m tolerance)
• Registry pattern: @register_point_generator("IfcWall") — one function per element type
• Door positions use ifcopenshell.geom.create_shape() for actual mesh center (not placement origin)
• T-junction detection for wall-wall meetings
• Cached as <stem>.connection_graph.json

See: 02_connection_graph.md

2. MEP Cable Routing

Files: tools/_mep_utils.py + tools/_spatial_graph.py + tools/mep_routing.py

• Auto-places lights (center-top of room) and switches (next to door, 1.05m height)
• Waypoint graph with ~15 nodes per room, axis-aligned edges only (no diagonals)
• A* pathfinding via networkx produces right-angle cable paths
• Routes returned as 3D point arrays for viewer rendering

See: 03_mep_routing.md

3. DIN 18015-3 Installation Zones

Files: tools/_wall_zones.py + tools/_ceiling_zones.py

• Computes installation zones per German electrical norms on wall and ceiling surfaces
• Wall zones: horizontal/vertical corridors, T-junction splitting, exterior face detection
• Ceiling zones: per-IfcSpace (one slab spans multiple rooms, walls divide below)
• Solid ceiling: ZD-r perimeter bands (30cm wide, 20cm from wall), ZD-t at doors (15cm offset)
• False ceiling: full fly zone 10cm below ceiling with strain relief flags (Zugentlastung)
• Green (allowed), Red (forbidden), Yellow (dead zone), Blue (preferred paths)
• Three modes: normal, false_ceiling, false_floor
• Cached as <stem>.wall_zones_<mode>.json

See: 04_wall_zones.md

4. 3D/2D Viewer

Files: templates/viewer.html

• Three.js + web-ifc with auto-detected coordinate mapping (ifcToThree())
• Overlays: space containers, connection graph, cable routes, wall zones
• 2D plan view with section plane, wall outlines, darkened slabs
• All backend data in IFC world coords, frontend transforms via coordMapping = {perm, sgn, off}

See: 05_viewer.md

How They Connect

IFC File
  ├── Connection Graph  → topological nodes + edges for all elements
  │     └── used by MEP Routing (future: replace waypoint graph with connection graph)
  ├── MEP Routing       → light/switch placement + cable paths
  ├── Wall/Ceiling Zones → forbidden/allowed/preferred areas on walls + ceilings
  └── 3D Viewer         → renders all overlays using ifcToThree() coordinate mapping
        ├── /spaces endpoint        → space containers + coordinate mapping detection
        ├── /connection_graph       → graph overlay
        ├── /analyze (mep_routing)  → route overlay
        └── /wall_zones             → zone overlay

The connection graph provides the topological foundation. Wall zones constrain where cables can go. MEP routing uses both to compute valid paths. The viewer visualizes everything.