blendiff 0.4.0

Semantic diff, snapshot history, and assisted merge for Blender .blend files

BlenDiff

Semantic diff, snapshot history, and assisted merge for Blender .blend files.

BlenDiff compares two .blend file states using Blender's Python API — not binary diffing — and provides a full assisted merge system. It ships as both a Blender addon and a pip-installable pure-Python library for headless/CI use.

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Features

• Snapshot history — named, timestamped snapshots stored in a human-readable .blendiff JSON sidecar next to your .blend file
• Object & collection diffing — detects added, removed, and modified objects with per-property change tracking (transform, visibility, collection membership)
• Material node graph diffing — per-node, per-socket comparison including image names, input values, and rewired links
• Render settings diffing — engine, resolution, sampling, output format, color management, Cycles and EEVEE sub-settings
• Three-way merge — conflict detection and per-property resolution (Use A / Use B / Use Base) with a Blender UI
• Annotated HTML export — self-contained dark-themed report with per-entry annotation textareas and JSON round-trip
• Headless CLI — run diffs in CI without launching Blender

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Installation

As a pip library (no Blender required)

pip install blendiff

As a Blender addon

Download the latest blendiff.zip from Releases and install via Edit → Preferences → Add-ons → Install.

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CLI Usage

# List snapshots in a sidecar file
blendiff list scene.blendiff

# Compare two snapshots
blendiff compare scene.blendiff "Before rigging" "After rigging"

# Fail CI if any changes exist
blendiff latest scene.blendiff --fail-on-changes

# Export an HTML report
blendiff compare scene.blendiff "v1" "v2" --output report.html

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Python API

from blendiff.storage.sidecar import SidecarManager
from blendiff.diff_engine.diff_engine import DiffEngine

mgr = SidecarManager("scene.blendiff")
snaps = {s.label: s for s in mgr.list_snapshots()}

engine = DiffEngine()
result = engine.compare(snaps["v1"].data, snaps["v2"].data)

# Render settings diff
print(result.render_diff.summary())

# Object diffs
for diff in result.object_diffs:
    print(diff.name, diff.kind)
    for change in diff.changes:
        print(" ", change.property_path, change.old_value, "→", change.new_value)

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Architecture

blendiff/
├── data_model/      # Dataclasses — SceneDiff, RenderDiff, MergeProposal, …
├── diff_engine/     # Pure comparison logic — no bpy
├── serializer/      # mathutils → JSON-safe types
├── storage/         # .blendiff sidecar CRUD
├── export/          # Self-contained HTML report generation
├── cli/             # Headless CLI + importable Python API
├── extractor/       # bpy readers (Blender-only)
└── ui/              # Blender panels and operators (Blender-only)

The extractor is the only bpy-touching module. Everything downstream is pure Python and fully testable without Blender.

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Running Tests

pip install blendiff[dev]
pytest tests/ -v

224+ tests, all passing without a Blender installation.

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CI Integration

# .github/workflows/diff.yml
- name: Check for scene changes
  run: blendiff latest scene.blendiff --fail-on-changes

See docs/ci_example.yml for a full GitHub Actions workflow template.

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License

MIT