How to get the count of HATCH boundary paths?

[ghost]

Hi guys,

Is there a way to find Loops count and to know if this is a Outer or Inner Loop?

[mozman]

Getting the count of boundary paths is the easy part: len(hatch.paths)

The nesting structure is more complicated:

1. A hatch can contain multiple geometrically independent areas in a single HATCH entity.
2. There is no reliable DXF attribute which indicates the geometrical meaning of a path like exterior or interior path
3. Paths can be deeply nested

There is a helper tool to create a complex recursive data structure which represents the nesting structure of HATCH boundary paths: ezdxf.path.fast_bbox_detection(), see the source code.

The fast_bbox_detection() function expects the boundary path as ezdxf.path.Path objects, the factory function ezdxf.path.from_hatch() converts all HATCH boundary paths into such Path objects, but the association to the source DXF boundary path get lost!

An example for HATCH processing is implemented in the drawing add-on, see the draw_hatch_entity() method in source code of the Frontend() class. Note: most backends require a specific winding orientation of the paths to represent filled areas or holes.