# NodeSlicer Technical Overview

NodeSlicer is a Blender extension designed for high-performance mesh slicing and G-code generation. It provides a node-based interface that abstracts away the complexity of 3D-to-2D geometry conversion, offering a pipeline for 3D printing workflows.

## Core Principles

1.  **Fast Slicing**: Bypasses the Blender CPU-bound Boolean modifiers by using vectorized plane-triangle intersection via NumPy.
2.  **Robust Geometry**: Leverages Shapely (built on GEOS) for all 2D operations, ensuring topological correctness in offset/buffering and boundary extraction.
3.  **Extensibility**: A custom Node Tree architecture allows for easy creation of new nodes for custom toolpath strategies or post-processing.
4.  **Blender Integration**: Deeply integrated into Blender's UI while maintaining a decoupled geometry engine for maximum performance.

## System Architecture

```mermaid
graph TD
    UI[Blender Node Editor] --> Eval[Node Evaluation Engine]
    Eval --> Capture[Mesh Capture - infra/blender_mesh_capture]
    Capture --> Slice[Slicing Logic - core/slice]
    Slice --> Gcode[G-code Generation - core/slice]
    Gcode --> Export[File Export]
```

## Data Lifecycle

- **Mesh Data**: Extracted from Blender as `(N, 4, 3)` NumPy arrays representing triangles and face normals.
- **2D Contours (Slices)**: Stored as a list of closed paths (NumPy arrays). Coordinates include Z-height. Topology (shells/holes) is managed via Pyclipper using the Even-Odd fill rule.
- **Toolpaths (Paths)**: Stored as a list of open or closed paths (NumPy arrays). These represent the actual motion lines of the 3D printer.
- **G-code**: Formatted strings that include travel moves (`G0`), extrusions (`G1`), and metadata (layer change comments).

## Important Files

- `__init__.py`: Node tree and evaluation engine definition.
- `core/slice.py`: Slicing and G-code generation algorithms.
- `infra/blender_mesh_capture.py`: High-performance mesh extraction from Blender.
- `registry.py`: Central registration of Blender classes.