# Blender Core Api

> >

- **Type:** Skill
- **Install:** `agentstack add skill-impertio-studio-blender-bonsai-ifcopenshell-sverchok-claude-skill-package-blender-core-api`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [Impertio-Studio](https://agentstack.voostack.com/s/impertio-studio)
- **Installs:** 0
- **Category:** [AI & ML](https://agentstack.voostack.com/c/ai-and-ml)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [Impertio-Studio](https://github.com/Impertio-Studio)
- **Source:** https://github.com/Impertio-Studio/Blender-Bonsai-ifcOpenshell-Sverchok-Claude-Skill-Package/tree/main/skills/blender/core/blender-core-api
- **Website:** https://github.com/OpenAEC-Foundation

## Install

```sh
agentstack add skill-impertio-studio-blender-bonsai-ifcopenshell-sverchok-claude-skill-package-blender-core-api
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# blender-core-api

## Quick Reference

### bpy Module Hierarchy

| Module | Purpose | Example |
|--------|---------|---------|
| `bpy.data` | All blend-file data (ID data blocks) | `bpy.data.objects["Cube"]` |
| `bpy.context` | Current state (active object, mode, selection) | `bpy.context.active_object` |
| `bpy.ops` | Operators with undo support | `bpy.ops.mesh.primitive_cube_add()` |
| `bpy.types` | Type definitions for all Blender structs | `class MyOp(bpy.types.Operator):` |
| `bpy.props` | Property definitions for custom data | `bpy.props.FloatProperty()` |
| `bpy.utils` | Utility functions (registration, paths) | `bpy.utils.register_class(cls)` |
| `bpy.app` | Application info (version, handlers) | `bpy.app.version` |
| `bpy.path` | Blender-aware path utilities | `bpy.path.abspath("//file.png")` |
| `bpy.msgbus` | Message bus for property notifications | `bpy.msgbus.subscribe_rna()` |

### bpy.data Collections (all versions)

```
bpy.data
├── .objects      ├── .meshes       ├── .materials    ├── .scenes
├── .collections  ├── .node_groups  ├── .images       ├── .textures
├── .lights       ├── .cameras      ├── .curves       ├── .armatures
├── .worlds       ├── .actions      └── ... (30+ total collection types)
```

### Critical Warnings

**NEVER** cache `bpy.data` object references across undo operations — undo invalidates all pointers.

**NEVER** call `bpy.ops.*` from a background thread — all bpy calls MUST run on the main thread.

**NEVER** use dict context overrides in Blender 4.0+ — use `context.temp_override()` instead.

**NEVER** modify scene data inside `Panel.draw()` — draw callbacks are read-only.

**NEVER** access `mesh.vertices` while in Edit Mode — the data is not synchronized. Use `bmesh.from_edit_mesh()` instead.

---

## Essential Patterns

### Pattern 1: Data Access vs. Operators

Use `bpy.data` for direct data manipulation (fast, no undo). Use `bpy.ops` only when undo support or user-facing actions are required.

```python
# Blender 3.x/4.x/5.x: CORRECT: direct data access (no context required)
obj = bpy.data.objects.get("Cube")
if obj:
    obj.location = (1.0, 0.0, 0.0)

# Blender 3.x/4.x/5.x: CORRECT: operator when undo is needed
bpy.ops.object.location_clear()  # Requires correct context
```

### Pattern 2: Context Overrides (version-critical)

```python
# Blender 3.x ONLY: BROKEN in 4.0+
override = bpy.context.copy()
override['active_object'] = obj
bpy.ops.object.modifier_apply(override, modifier="Subsurf")  # REMOVED in 4.0

# Blender 3.2+ and 4.x/5.x: CORRECT
with bpy.context.temp_override(object=obj, active_object=obj):
    bpy.ops.object.modifier_apply(modifier="Subsurf")

# Blender 4.x/5.x: Override area for viewport operators
for window in bpy.context.window_manager.windows:
    for area in window.screen.areas:
        if area.type == 'VIEW_3D':
            with bpy.context.temp_override(window=window, area=area):
                bpy.ops.view3d.snap_cursor_to_center()
            break
```

### Pattern 3: ID Data Block Lifecycle

```python
# Blender 3.x/4.x/5.x: create, link, manage user count
mesh = bpy.data.meshes.new("MyMesh")         # Creates data block
obj = bpy.data.objects.new("MyObject", mesh) # Creates object referencing mesh
bpy.context.collection.objects.link(obj)     # REQUIRED: link to scene collection

# Prevent orphaned data from being purged on save
mesh.use_fake_user = True  # Keeps data even with zero users

# Remove data block
bpy.data.meshes.remove(mesh)
```

### Pattern 4: Dependency Graph

```python
# Blender 3.x/4.x/5.x: get evaluated (post-modifier) data
depsgraph = bpy.context.evaluated_depsgraph_get()
obj_eval = obj.evaluated_get(depsgraph)       # Evaluated object
mesh_eval = obj_eval.to_mesh()                # Evaluated mesh (read-only)
# ... read mesh_eval ...
obj_eval.to_mesh_clear()                      # ALWAYS clean up

# Iterate ALL instances (including collection/particle instances)
for instance in depsgraph.object_instances:
    obj = instance.object          # Evaluated object
    matrix = instance.matrix_world # World transform
    is_inst = instance.is_instance # True for non-base instances
```

---

## Common Operations

### Object Selection and Activation

```python
# Blender 3.x/4.x/5.x: correct API (2.80+ style)
obj.select_set(True)                              # NOT obj.select = True
bpy.context.view_layer.objects.active = obj       # NOT scene.objects.active
```

### RNA Introspection

```python
# Blender 3.x/4.x/5.x: inspect properties via RNA
obj = bpy.context.active_object
for prop in obj.bl_rna.properties:
    print(f"{prop.identifier}: {prop.type}")

# Get type info on a specific property
prop = obj.bl_rna.properties['location']
print(prop.array_length)  # 3
print(prop.subtype)       # 'TRANSLATION'
```

### Application Handlers

```python
# Blender 3.x/4.x/5.x
from bpy.app.handlers import persistent

@persistent  # Decorator required to survive file load
def on_depsgraph_update(scene, depsgraph):
    for update in depsgraph.updates:
        if update.is_updated_geometry:
            print(f"Geometry changed: {update.id.name}")

bpy.app.handlers.depsgraph_update_post.append(on_depsgraph_update)

# Unregister in addon unregister():
bpy.app.handlers.depsgraph_update_post.remove(on_depsgraph_update)
```

### Version Detection

```python
# Blender 3.x/4.x/5.x
major, minor, patch = bpy.app.version  # e.g., (4, 2, 0)

if bpy.app.version >= (4, 0, 0):
    # Use temp_override, NodeTree.interface, bone.collections
    pass
if bpy.app.version >= (5, 0, 0):
    # Use gpu module exclusively for drawing
    pass
```

### Creating and Linking Objects

```python
# Blender 3.x/4.x/5.x: complete pattern
mesh = bpy.data.meshes.new("MyMesh")
verts = [(0, 0, 0), (1, 0, 0), (1, 1, 0), (0, 1, 0)]
faces = [(0, 1, 2, 3)]
mesh.from_pydata(verts, [], faces)
mesh.update()  # ALWAYS call after from_pydata

obj = bpy.data.objects.new("MyObject", mesh)
bpy.context.collection.objects.link(obj)  # REQUIRED — objects without links are invisible
```

### Restricted Contexts

| Callback | Forbidden Operations |
|----------|---------------------|
| `Panel.draw()` | `bpy.ops.*`, property modification |
| `depsgraph_update_post` | Adding/removing objects, scene mutation |
| `render_pre/post` | Most `bpy.ops.*` |
| Background mode | All viewport operators, OpenGL |

---

## Version-Specific Migration Rules

| Feature | Blender 3.x | Blender 4.0+ |
|---------|-------------|--------------|
| Context override | `bpy.ops.foo(override_dict, ...)` | `context.temp_override(...)` |
| Mesh bevel weight | `edge.bevel_weight` | `mesh.attributes["bevel_weight_edge"]` |
| Mesh crease | `edge.crease` | `mesh.attributes["crease_edge"]` |
| Node group sockets | `node_group.inputs.new(...)` | `node_group.interface.new_socket(...)` |
| Bone layers | `bone.layers[i]` | `bone.collections` |

| Feature | Blender 4.x | Blender 5.0+ |
|---------|-------------|--------------|
| Drawing | `bgl` module (deprecated) | `gpu` module (REQUIRED) |
| Compositing | `scene.node_tree` | `scene.compositing_node_group` |
| EEVEE identifier | `BLENDER_EEVEE` or `BLENDER_EEVEE_NEXT` | `BLENDER_EEVEE` |

---

## Reference Links

- [references/methods.md](references/methods.md) — Complete API signatures for bpy.data, bpy.context, bpy.ops, bpy.types, Depsgraph
- [references/examples.md](references/examples.md) — Working code examples verified against official documentation
- [references/anti-patterns.md](references/anti-patterns.md) — What NOT to do, with WHY explanations

### Official Sources

- https://docs.blender.org/api/current/info_quickstart.html
- https://docs.blender.org/api/current/info_overview.html
- https://docs.blender.org/api/current/bpy.context.html
- https://docs.blender.org/api/current/bpy.types.Depsgraph.html
- https://docs.blender.org/api/current/bpy.types.Context.html

## 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](https://github.com/Impertio-Studio)
- **Source:** [Impertio-Studio/Blender-Bonsai-ifcOpenshell-Sverchok-Claude-Skill-Package](https://github.com/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.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-impertio-studio-blender-bonsai-ifcopenshell-sverchok-claude-skill-package-blender-core-api
- Seller: https://agentstack.voostack.com/s/impertio-studio
- Browse the marketplace: https://agentstack.voostack.com/browse

---
Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.