Bonsai Impl Bcf

BCF Workflows in Bonsai

> Version: Bonsai v0.8.x | Blender 4.2.0+ | Python 3.11 > Module path: bonsai.bim.module.bcf — NEVER blenderbim.bim.module.bcf > BCF versions: v2.1 and v3.0 (via bcf.bcfxml library bundled with IfcOpenShell) > Dependencies: bonsai-core-architecture, bonsai-syntax-elements

Critical Warnings

1. ALWAYS set scene.BCFProperties.author to a valid email BEFORE creating topics or comments. Default "john@doe.com" is a placeholder — replace it.
2. ALWAYS use BcfStore.get_bcfxml() to access BCF data. NEVER access BcfStore.bcfxml directly — get_bcfxml() handles lazy initialization and path resolution.
3. ALWAYS call bpy.ops.bim.save_bcf_project() to persist changes. BCF modifications are in-memory only until saved.
4. NEVER mix BCF v2.1 and v3.0 operations on the same project. The version is set at creation/load time and MUST remain consistent.
5. ALWAYS ensure an active camera exists before calling bpy.ops.bim.add_bcf_viewpoint(). The operator polls for an active scene camera.
6. NEVER assume viewpoint coordinates match the loaded IFC model coordinates. Viewpoint activation applies georeference offset corrections.
7. ALWAYS use bonsai.* imports. NEVER use blenderbim.* — renamed in 2024 (v0.8.0+).
8. BCF v3.0 REQUIRES non-empty status and type fields on topics. These are optional in v2.1 but mandatory in v3.0.

---

Architecture Overview

The BCF module diverges from Bonsai's standard core/tool/operator pattern. At v0.8.x, most domain logic lives directly in operators rather than in a separate core/bcf.py. The tool/bcf.py provides version-agnostic helper methods for topic data access.

+----------------------------------------------------------+
|  DELIVERY LAYER  — bim/module/bcf/                        |
|  operator.py (30+ operators), prop.py, ui.py              |
+----------------------------------------------------------+
|  TOOL LAYER      — tool/bcf.py                            |
|  Version-agnostic getters/setters for topic data          |
+----------------------------------------------------------+
|  DATA LAYER      — bcfstore.py (BcfStore singleton)       |
|  Class-level singleton wrapping bcf.bcfxml.BcfXml         |
+----------------------------------------------------------+
|  LIBRARY         — bcf.v2.bcfxml / bcf.v3.bcfxml          |
|  BCF-XML parser bundled with IfcOpenShell                 |
+----------------------------------------------------------+

Key singleton: BcfStore manages BCF data as a class-level singleton. Only ONE BCF project is loaded at a time. Access via BcfStore.get_bcfxml().

Properties access: bpy.context.scene.BCFProperties (or tool.Bcf.get_bcf_props()) holds all BCF UI state.

---

Decision Tree: BCF Workflow Selection

What BCF operation do you need?
│
├── Start a new BCF project?
│   └── bpy.ops.bim.new_bcf_project()
│       ├── Set props.bcf_version = "2" (v2.1) or "3" (v3.0) FIRST
│       └── Sets up empty BcfXml in BcfStore
│
├── Load an existing BCF file?
│   └── bpy.ops.bim.load_bcf_project(filepath="/path/to/file.bcf")
│       └── Auto-detects version, populates BcfStore + topics
│
├── Create/manage issues?
│   ├── Add topic: bpy.ops.bim.add_bcf_topic()
│   ├── Edit topic: bpy.ops.bim.edit_bcf_topic()
│   ├── View topic: bpy.ops.bim.view_bcf_topic(topic_guid="...")
│   └── Remove topic: bpy.ops.bim.remove_bcf_topic(guid="...")
│
├── Add visual context to an issue?
│   ├── Capture viewpoint: bpy.ops.bim.add_bcf_viewpoint()
│   ├── Restore viewpoint: bpy.ops.bim.activate_bcf_viewpoint()
│   └── Remove viewpoint: bpy.ops.bim.remove_bcf_viewpoint()
│
├── Add discussion to an issue?
│   ├── Add comment: bpy.ops.bim.add_bcf_comment()
│   ├── Edit comment: bpy.ops.bim.edit_bcf_comment()
│   └── Remove comment: bpy.ops.bim.remove_bcf_comment(comment_guid="...")
│
├── Attach documents/references?
│   ├── Reference link: bpy.ops.bim.add_bcf_reference_link()
│   ├── Document ref: bpy.ops.bim.add_bcf_document_reference()
│   ├── BIM snippet: bpy.ops.bim.add_bcf_bim_snippet()
│   └── Header file: bpy.ops.bim.add_bcf_header_file()
│
├── Save BCF to disk?
│   └── bpy.ops.bim.save_bcf_project(filepath="/path/to/output.bcf")
│
└── Close BCF project?
    └── bpy.ops.bim.unload_bcf_project()

---

Essential Patterns

Pattern 1: BCF Project Lifecycle

# Bonsai v0.8.x: Complete BCF project lifecycle
import bpy

props = bpy.context.scene.BCFProperties

# Step 1: Set author (REQUIRED before any topic/comment creation)
props.author = "architect@example.com"

# Step 2: Choose BCF version and create project
props.bcf_version = "3"  # "2" for v2.1, "3" for v3.0
bpy.ops.bim.new_bcf_project()

# Step 3: Work with topics, viewpoints, comments...
# (see patterns below)

# Step 4: Save to disk
bpy.ops.bim.save_bcf_project(filepath="/path/to/issues.bcf")

# Step 5: Unload when done
bpy.ops.bim.unload_bcf_project()

Pattern 2: Load Existing BCF File

# Bonsai v0.8.x: Load and inspect BCF file
import bpy

# Load BCF file (auto-detects v2.1 or v3.0)
bpy.ops.bim.load_bcf_project(filepath="/path/to/issues.bcf")

# Access loaded data
props = bpy.context.scene.BCFProperties
print(f"Project: {props.name}")
print(f"Version: BCF v{props.bcf_version}")
print(f"Topics: {len(props.topics)}")

# Iterate topics
for topic in props.topics:
    print(f"  [{topic.status}] {topic.title} (GUID: {topic.name})")

Pattern 3: Create Topic with Metadata

# Bonsai v0.8.x: Create and configure a BCF topic
import bpy

props = bpy.context.scene.BCFProperties
props.author = "engineer@example.com"

# Create topic
bpy.ops.bim.add_bcf_topic()

# Get the newly created topic (last in list)
topic = props.topics[props.active_topic_index]

# Set metadata
topic.title = "MEP clash at Level 2 corridor"
topic.type = "Error"
topic.status = "Open"
topic.priority = "Critical"
topic.assigned_to = "mep-coordinator@example.com"
topic.description = "HVAC duct intersects structural beam at grid B-4."

# Persist changes to the BCF data structure
bpy.ops.bim.edit_bcf_topic()

Pattern 4: Capture Viewpoint with Camera Snapshot

# Bonsai v0.8.x: Capture viewpoint for active topic
import bpy

# PREREQUISITE: Active camera MUST exist
if bpy.context.scene.camera is None:
    raise RuntimeError("Set an active camera before capturing a viewpoint.")

# Position camera at the issue location
camera = bpy.context.scene.camera
camera.location = (10.0, -5.0, 3.0)
camera.rotation_euler = (1.22, 0.0, 0.78)

# Capture viewpoint (records camera state + element visibility + snapshot)
bpy.ops.bim.add_bcf_viewpoint()
# This operator:
# 1. Reads camera position/orientation from active scene camera
# 2. Records component visibility and selection state
# 3. Renders a PNG snapshot via bpy.ops.render.opengl()
# 4. Stores clipping planes if present

Pattern 5: Add Comments to a Topic

# Bonsai v0.8.x: Add comments to the active BCF topic
import bpy

props = bpy.context.scene.BCFProperties
props.author = "reviewer@example.com"

# Set comment text
props.comment = "Duct routing needs to be lowered by 200mm to clear beam."

# Optionally link to active viewpoint
props.has_related_viewpoint = True  # Links comment to current viewpoint

# Create comment
bpy.ops.bim.add_bcf_comment()

Pattern 6: Activate (Restore) a Viewpoint

# Bonsai v0.8.x: Restore a saved viewpoint
import bpy

props = bpy.context.scene.BCFProperties
topic = props.active_topic

# Viewpoints are accessed via the topic's viewpoints enum
# Activate the currently selected viewpoint
bpy.ops.bim.activate_bcf_viewpoint()
# This restores:
# - Camera position and orientation
# - Component visibility/selection state
# - Clipping planes
# - Applies georeference offset correction

# To activate a specific viewpoint by GUID:
bpy.ops.bim.activate_bcf_viewpoint(viewpoint_guid="abc-123-def-456")

---

BCF Version Differences

| Feature | BCF v2.1 | BCF v3.0 | |---------|----------|----------| | props.bcf_version value | "2" | "3" | | Topic status field | Optional | REQUIRED (edit fails without it) | | Topic type field | Optional | REQUIRED (edit fails without it) | | Document storage | Per-topic (TopicDocumentReference) | Global registry (bcfxml.documents) | | API support | No | Yes (OpenCDE compliant) | | Data model module | bcf.v2.model | bcf.v3.model | | BcfXml class | bcf.v2.bcfxml.BcfXml | bcf.v3.bcfxml.BcfXml |

Version Detection

# Bonsai v0.8.x: Detecting BCF version at runtime
from bonsai.bim.module.bcf.bcfstore import BcfStore

bcfxml = BcfStore.get_bcfxml()
if bcfxml is None:
    raise RuntimeError("No BCF project loaded.")

version_id = bcfxml.version.version_id or ""
is_v2 = version_id.startswith("2")
is_v3 = version_id.startswith("3")

---

Common Operations

Import BCF from External Tool

# Bonsai v0.8.x: Load BCF from Solibri, Navisworks, etc.
import bpy

# Load external BCF file
bpy.ops.bim.load_bcf_project(filepath="/path/to/coordination.bcf")

props = bpy.context.scene.BCFProperties

# Iterate all topics
for i, topic in enumerate(props.topics):
    print(f"Topic {i}: [{topic.status}] {topic.title}")

    # View topic to load its details
    bpy.ops.bim.view_bcf_topic(topic_guid=topic.name)

    # Load comments for this topic
    bpy.ops.bim.load_bcf_comments(topic_guid=topic.name)
    for comment in topic.comments:
        print(f"  Comment by {comment.author}: {comment.comment}")

Export BCF for External Tools

# Bonsai v0.8.x: Save BCF for sharing with other BIM tools
import bpy

# Save current BCF project
bpy.ops.bim.save_bcf_project(filepath="/path/to/export.bcf")

# Save to same path (overwrite)
bpy.ops.bim.save_bcf_project(save_current_bcf=True)

Link BCF Topic to IFC Elements

# Bonsai v0.8.x: Reference IFC elements in BCF viewpoint
import bpy
import bonsai.tool as tool

model = tool.Ifc.get()
if model is None:
    raise RuntimeError("No IFC project loaded.")

# Select the clashing elements in Blender viewport
bpy.ops.object.select_all(action='DESELECT')

# Find elements by GlobalId and select them
for global_id in ["2O2Fr$t4X7Zf8NOew3FLOH", "1kTvXnbbzEWu00n_qpFOat"]:
    entity = model.by_guid(global_id)
    obj = tool.Ifc.get_object(entity)
    if obj:
        obj.select_set(True)

# Capture viewpoint: selected elements are recorded as BCF components
bpy.ops.bim.add_bcf_viewpoint()

Clash Detection to BCF Workflow

# Bonsai v0.8.x: Convert clash results to BCF issues
import bpy

# Step 1: Run clash detection with BCF output
bpy.ops.bim.execute_ifc_clash()
# Save output as .bcf file when prompted

# Step 2: Load the clash BCF into BCF panel
bpy.ops.bim.load_bcf_project(filepath="/path/to/clashes.bcf")

# Each clash becomes a BCF topic with:
# - Viewpoint at clash location
# - Component references for both clashing elements
# - Metadata about clash type and severity

Attach Documents and References

# Bonsai v0.8.x: Add reference links and documents to a topic
import bpy

props = bpy.context.scene.BCFProperties

# Add a reference link (URL)
props.reference_link = "https://project.example.com/issues/MEP-042"
bpy.ops.bim.add_bcf_reference_link()

# Add a document reference
props.document_reference = "/path/to/specification.pdf"
props.document_reference_description = "MEP specification section 4.2"
bpy.ops.bim.add_bcf_document_reference()

# Add a BIM snippet (IFC fragment for context)
props.bim_snippet_reference = "/path/to/fragment.ifc"
props.bim_snippet_type = "IfcSharedBuildingElements"
props.bim_snippet_schema = "IFC4"
bpy.ops.bim.add_bcf_bim_snippet()

Add Labels and Related Topics

# Bonsai v0.8.x: Organize topics with labels and relations
import bpy

props = bpy.context.scene.BCFProperties

# Add labels to active topic
props.label = "MEP"
bpy.ops.bim.add_bcf_label()
props.label = "Structural"
bpy.ops.bim.add_bcf_label()

# Add related topic (requires another topic to exist)
# related_topic is an EnumProperty listing other topics
bpy.ops.bim.add_bcf_related_topic()

Extract Embedded Files

# Bonsai v0.8.x: Extract files embedded in BCF topics
import bpy

# Extract a header file by index
bpy.ops.bim.extract_bcf_file(entity_type="HEADER_FILE", index=0)

# Extract BIM snippet
bpy.ops.bim.extract_bcf_file(entity_type="BIM_SNIPPET", index=0)

# Extract document reference
bpy.ops.bim.extract_bcf_file(entity_type="DOCUMENT_REFERENCE", index=0)

---

BcfStore Singleton

The BcfStore class (at bonsai.bim.module.bcf.bcfstore) manages BCF session state:

from bonsai.bim.module.bcf.bcfstore import BcfStore

# Get the active BCF project (lazy-loads from props.bcf_file)
bcfxml = BcfStore.get_bcfxml()

# Set BCF data explicitly
BcfStore.set(bcfxml, filepath)

# Load by filepath (triggers lazy load on next get_bcfxml())
BcfStore.set_by_filepath("/path/to/file.bcf")

# Unload BCF session
BcfStore.unload_bcfxml()

Key behavior:

• get_bcfxml() calls bcf.bcfxml.load(filepath) from props.bcf_file on first access
• set() auto-detects BCF version from bcfxml.version.version_id and updates props.bcf_version
• Silently handles load exceptions (e.g., permission denied) — check return value for None
• Resolves relative paths against the .blend file directory

---

BCFProperties Quick Reference

Access via bpy.context.scene.BCFProperties:

| Property | Type | Purpose | |----------|------|---------| | author | str | Author email — REQUIRED before creating topics/comments | | bcf_version | enum | "2" (v2.1) or "3" (v3.0) | | bcf_file | str | Path to loaded BCF file | | name | str | Project name | | topics | Collection[BcfTopic] | All loaded topics | | active_topic_index | int | Currently selected topic index | | comment | str | Input field for new comment text | | has_related_viewpoint | bool | Link new comment to active viewpoint | | reference_link | str | Input field for reference link URL | | label | str | Input field for label text |

Computed property: props.active_topic returns BcfTopic at active_topic_index or None.

---

Drag-and-Drop Support

Bonsai registers BCFFileHandlerOperator with bl_file_extensions = ".bcf", enabling drag-and-drop import of BCF files directly into Blender. The handler calls bim.load_bcf_project with the dropped file path.

---

Reference Links

• [BCF API Methods](references/methods.md) — Complete operator signatures and BcfStore API
• [Working Examples](references/examples.md) — End-to-end BCF workflow examples
• [Anti-Patterns](references/anti-patterns.md) — What NOT to do when implementing BCF workflows

Dependencies

• bonsai-core-architecture — Three-layer architecture, IfcStore, operator execution pattern
• bonsai-syntax-elements — IFC element access for linking BCF issues to IFC entities

Sources

• Bonsai BCF source: src/bonsai/bonsai/bim/module/bcf/ (operator.py, prop.py, bcfstore.py)
• Bonsai BCF tool: src/bonsai/bonsai/tool/bcf.py
• BCF library: bcf.v2.bcfxml / bcf.v3.bcfxml (bundled with IfcOpenShell)
• Bonsai Documentation: https://docs.bonsaibim.org
• IfcOpenShell GitHub: https://github.com/IfcOpenShell/IfcOpenShell

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: Impertio-Studio
• Source: Impertio-Studio/Blender-Bonsai-ifcOpenshell-Sverchok-Claude-Skill-Package
• License: MIT
• Homepage: https://github.com/OpenAEC-Foundation

Install and usage instructions live in the source repository linked above.