Bonsai Clash Detection Implementation

Version: Bonsai v0.8.x | IfcClash (from IfcOpenShell v0.8.x) | Blender 4.2.0+ | Python 3.11 Module path: bonsai.bim.module.clash — NEVER blenderbim.bim.module.clash Engine: IfcClash — frontend for FCL (Flexible Collision Library)

Critical Warnings

1. ALWAYS save IFC files to disk BEFORE running clash detection. IfcClash reads files from disk, NOT from Blender's in-memory model.
2. ALWAYS define BOTH Group A and Group B in every clash set, even for intra-model checks (e.g., structural vs. MEP in the same file).
3. ALWAYS use filter_groups to limit clash scope. Unfiltered detection on large models produces excessive runtime and noise.
4. ALWAYS use bim.smart_clash_group for result sets exceeding 50 clashes. Manual review of hundreds of individual clashes is impractical.
5. NEVER expect real-time clash checking. Clash detection is a batch operation — there is NO live monitoring.
6. NEVER use collision mode with allow_touching=True for detecting hard overlaps — this generates false positives where elements share surfaces. Use intersection mode instead.
7. ALWAYS specify an output path (.bcf or .json) before executing clash detection.
8. ALWAYS use bonsai.* imports. NEVER use blenderbim.* — renamed in 2024 (v0.8.0+).