Get HATCH to populate the entity boundary

[LongJun88]

HI dear mozman：
How to read "HATCH" fill entity boundary, and obtain the corresponding boundary path coordinates?Thank you very much for giving me the test code.

[mozman]

The HATCH entity is very complex, here are the docs.

A good starting point to learn how to render the HATCH entity is the Frontend.draw_hatch_entity() method in the module frontend.py of the drawing add-on.

Some random topics you have to know:

• a HATCH can contain multiple separated hatched areas, where each area has an exterior path and holes and the holes can have holes and so on ...
• the boundary paths are in no particular order, not grouped by areas and are not tagged as exterior path or holes in any kind, the path flags external, outermost or default are not helpful to classifying the paths
• boundary paths can be degenerated, which means they do not represent a closed path
• the path orientation can be clockwise or counter-clockwise and has no special meaning

[LongJun88]

Mozman: Thank you very much. Let me take a look