I am using ezdxf to import a .dxf file into Python. It works smoothly. I get a list of lines and arcs.
How do I figure out which lines and arcs are connected to each other? Are they somehow indexed or do I need to search start and end points of lines and arcs and match them afterwards?
What I need to find are the closed lines in the .dxf file.
You have to match line and arc end points manually.
Get the end points of arcs with default extrusion (0, 0, 1):
from ezdxf.math import Vector
start_point = Vector.from_deg_angle(arc.dxf.start_angle, arc.dxf.radius)
end_point = Vector.from_deg_angle(arc.dxf.end_angle, arc.dxf.radius)
Add to arc center:
s = start_point + arc.dxf.center
e = end_point + arc.dxf.center
If the Object Coordinate System (OCS) defined by arc.dxf.extrusion is different from (0, 0, 1), a transformation to the World Coordinate System (WCS) has to be done:
ocs = arc.ocs()
s = ocs.to_wcs(s)
e = ocs.to_wcs(e)
Next ezdxf version v0.11 will have Arc.start_point and Arc.end_point properties, which will return the WCS coordinates.
Important: Don't compare with the equal operator (==), use math.isclose() or better Vector.isclose() like:
s.isclose(line.dxf.start, abs_tol=1e-6)
e.isclose(line.dxf.start, abs_tol=1e-6)
s.isclose(line.dxf.end, abs_tol=1e-6)
e.isclose(line.dxf.end, abs_tol=1e-6)
Set absolute tolerance according to your needs.