ExtensionLine / DimensionLine complain that start > end

[jdegenstein]

This code is adapted from docs/objects_2d.py:

std = Draft()

# [ExtensionLine]
with BuildSketch() as e_line:
    with BuildLine():
        l1 = Polyline((20, 40), (-40, 40), (-40, -40), (20, -40))
        RadiusArc(l1 @ 0, l1 @ 1, 50)
    make_face()
    edg = e_line.edges().sort_by(Axis.X)[0]
    ExtensionLine(border=edg, offset=10, draft=std)
    outside_curve = e_line.edges().sort_by(Axis.X)[-1]
    ExtensionLine(border=outside_curve, offset=10, label_angle=True, draft=std)

# [TechnicalDrawing]
with BuildSketch() as tech_drawing:
    with Locations((0, 20)):
        add(e_line)
    TechnicalDrawing()

Returns:

ValueError                                Traceback (most recent call last)
     24     ExtensionLine(border=edg, offset=10, draft=std)
     25     outside_curve = e_line.edges().sort_by(Axis.X)[-1]
---> 26     ExtensionLine(border=outside_curve, offset=10, label_angle=True, draft=std)
     28 # [TechnicalDrawing]
     29 with BuildSketch() as tech_drawing:

File c:\Users\someuser\.conda\envs\ocp_vscode\Lib\site-packages\build123d\drafting.py:562, in ExtensionLine.__init__(self, border, offset, draft, sketch, label, arrows, tolerance, label_angle, project_line, mode)
    560     e_line_shape = sweep(line_pen, extension_line, mode=Mode.PRIVATE)
    561     e_lines.append(e_line_shape)
--> 562 d_line = DimensionLine(
    563     dimension_path,
    564     draft,
    565     sketch,
    566     label,
    567     arrows,
    568     tolerance,
    569     label_angle,
    570     mode=Mode.PRIVATE,
    571 )
    572 self.dimension = d_line.dimension  #: length of the dimension
    574 e_line_sketch = Sketch(children=e_lines + d_line.faces())

File c:\Users\someuser\.conda\envs\ocp_vscode\Lib\site-packages\build123d\drafting.py:410, in DimensionLine.__init__(self, path, draft, sketch, label, arrows, tolerance, label_angle, mode)
    406 if label_length + arrows.count(True) * draft.arrow_length < path_length:
    407     shaft_length = (path_length - label_length) / 2 - draft.pad_around_text
    408     shaft_pair = [
    409         path_obj.trim(0.0, shaft_length / path_length),
--> 410         path_obj.trim(1.0 - shaft_length / path_length, 1.0),
    411     ]
    412 else:
    413     shaft_length = 2 * draft.arrow_length

File c:\Users\someuser\.conda\envs\ocp_vscode\Lib\site-packages\build123d\topology.py:7785, in Wire.trim(self, start, end)
   7783     u_start = edge.param_at_point(trim_start_point)
   7784     u_end = edge.param_at_point(trim_end_point)
-> 7785     edge = edge.trim(u_start, u_end)
   7786 elif contains_start:
   7787     u_value = edge.param_at_point(trim_start_point)

File c:\Users\someuser\.conda\envs\ocp_vscode\Lib\site-packages\build123d\topology.py:4609, in Edge.trim(self, start, end)
   4594 """trim
   4595 
   4596 Create a new edge by keeping only the section between start and end.
   (...)
   4606     Edge: trimmed edge
   4607 """
   4608 if start >= end:
-> 4609     raise ValueError(f"start ({start}) must be less than end ({end})")
   4611 new_curve = BRep_Tool.Curve_s(
   4612     copy.deepcopy(self).wrapped, self.param_at(0), self.param_at(1)
   4613 )
   4614 parm_start = self.param_at(start)

ValueError: start (0.8165271836783728) must be less than end (0.0)

I have also observed some non-repeatable sporadic behavior in which this fails on the first call to ExtensionLine (in the same way as above). Perhaps the line is reversed at some point?

[tshead]

Running the exact same code, I get a different error. MacOS and build123d 0.7.0:

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
Cell In[61], line 12
     10     #ExtensionLine(border=edg, offset=10, draft=std)
     11     outside_curve = e_line.edges().sort_by(Axis.X)[-1]
---> 12     ExtensionLine(border=outside_curve, offset=10, label_angle=True, draft=std)
     14 # [TechnicalDrawing]
     15 with BuildSketch() as tech_drawing:

File ~/miniconda3/envs/default/lib/python3.12/site-packages/build123d/drafting.py:562, in ExtensionLine.__init__(self, border, offset, draft, sketch, label, arrows, tolerance, label_angle, project_line, mode)
    560     e_line_shape = sweep(line_pen, extension_line, mode=Mode.PRIVATE)
    561     e_lines.append(e_line_shape)
--> 562 d_line = DimensionLine(
    563     dimension_path,
    564     draft,
    565     sketch,
    566     label,
    567     arrows,
    568     tolerance,
    569     label_angle,
    570     mode=Mode.PRIVATE,
    571 )
    572 self.dimension = d_line.dimension  #: length of the dimension
    574 e_line_sketch = Sketch(children=e_lines + d_line.faces())

File ~/miniconda3/envs/default/lib/python3.12/site-packages/build123d/drafting.py:409, in DimensionLine.__init__(self, path, draft, sketch, label, arrows, tolerance, label_angle, mode)
    406 if label_length + arrows.count(True) * draft.arrow_length < path_length:
    407     shaft_length = (path_length - label_length) / 2 - draft.pad_around_text
    408     shaft_pair = [
--> 409         path_obj.trim(0.0, shaft_length / path_length),
    410         path_obj.trim(1.0 - shaft_length / path_length, 1.0),
    411     ]
    412 else:
    413     shaft_length = 2 * draft.arrow_length

File ~/miniconda3/envs/default/lib/python3.12/site-packages/build123d/topology.py:8020, in Wire.trim(self, start, end)
   8017         if v_edge != 1:
   8018             new_edges.append(e.trim(v_edge, 1))
-> 8020 return Wire(new_edges)

File ~/miniconda3/envs/default/lib/python3.12/site-packages/build123d/topology.py:7819, in Wire.__init__(self, *args, **kwargs)
   7817     obj = wire.wrapped
   7818 elif edges:
-> 7819     obj = Wire._make_wire(edges, False if sequenced is None else sequenced)
   7821 super().__init__(
   7822     obj=obj,
   7823     label="" if label is None else label,
   7824     color=color,
   7825     parent=parent,
   7826 )

File ~/miniconda3/envs/default/lib/python3.12/site-packages/build123d/topology.py:8115, in Wire._make_wire(cls, edges, sequenced)
   8113         raise RuntimeError("Wire is empty")
   8114     elif wire_builder.Error() == BRepBuilderAPI_DisconnectedWire:
-> 8115         raise ValueError("Edges are disconnected")
   8117 return wire_builder.Wire()

ValueError: Edges are disconnected

Changing the problematic code from ExtensionLine to DimensionLine works, but doesn’t generate the desired output, of course:

DimensionLine(path=outside_curve, label_angle=True, draft=std)

[jdegenstein]

@tshead I can confirm that the error message has changed. I am seeing the same error message as you but I am running a slightly newer development version 0.7.1.dev4+g043629e. There have been some changes to edges/wire trim since this issue was created so I am not surprised the error has changed a bit.

[jdegenstein]

Alright, doing some more investigation, an internal object after being offset is producing a wire with three edges from a wire with one edge. The trim function is having trouble processing the three edge wire, after looking I have determined that running Wire.clean() will reduce the numbers of edges back down to one at which point ExtensionLine will run just fine. I am not sure this is the best general solution and I suspect that the issue may actually lie in the offset_2d method.

[tshead]

@jdegenstein I appreciate you looking into this, but I’m not following you on how to use Wire.clean() in this case - could you expound on that a bit?

Many thanks, Tim